THE ELECTRONICS AND ELECTRICAL

ENGINEERING LABORATORY

One of NIST’s seven Measurement and Standards Laboratories, EEEL conducts research, provides measurement services, and helps set standards in support of: the fundamental electronic technologies of semiconductors, magnetics, and superconductors; information and communications technologies, such as fi ber optics, photonics, microwaves, electronic displays, and electronics manufacturing supply chain collaboration; forensics and security measurement instrumentation; fundamental and practical physical standards and measurement services for electrical quantities; maintaining the quality and integrity of electrical power systems; and the development of nanoscale and microelectromechanical devices. EEEL provides support to law enforcement, corrections, and criminal justice agencies, including homeland security. EEEL consists of four programmatic divisions and two matrixmanaged offi ces:Semiconductor Electronics DivisionOptoelectronics DivisionQuantum Electrical Metrology DivisionElectromagnetics DivisionOffi ce of Microelectronics ProgramsOffi ce of Law Enforcement StandardsThis document describes the technical programs of the Optoelectronics Division. Similar documents describing the other Divisions and Offi ces are available. Contact NIST/EEEL, 100 Bureau Drive, MS 8100, Gaithersburg, MD 20899-8100, Telephone: (301) 975-2220, On the Web: www.eeel.nist.gov
ELECTRONICS AND ELECTRICAL

ENGINEERING LABORATORY

OPTOELECTRONICS

DIVISION

PROGRAMS, ACTIVITIES, AND

ACCOMPLISHMENTS

NISTIR 7369

January 2007

U.S. DEPARTMENT OF COMMERCE

Carlos M. Gutierrez, Secretary

Technology Administration

Robert Cresanti, Under Secretary of Commerce for Technology

National Institute of Standards and Technology

William Jeffrey, Director
Any mention of commercial products is for information only; it does not imply recommendation or endorsement by the National Institute of Standards and Technology nor does it imply 

that the products mentioned are necessarily the best available for the purpose.
Optoelectronics Division iii 

CONTENTS

Welcome..................................................................................................................................iv

About the Optoelectronics Division .........................................................................................v

Optoelectronics Division Staff ................................................................................................vi

Laser Radiometry .....................................................................................................................1

Display Metrology ...................................................................................................................6

High-Speed Measurements ....................................................................................................10

Interferometry and Polarimetry ..............................................................................................14

Spectral and Nonlinear Properties .........................................................................................19

Nanostructure Fabrication and Metrology .............................................................................23

Quantum Information and Terahertz Technology ..................................................................27

Optical Materials Metrology ..................................................................................................33

Semiconductor Growth and Devices .....................................................................................37

Appendix A: Major Laboratory Facilities .............................................................................41

Appendix B: NRC Post-Doc and Other Research Opportunities .........................................42

Appendix C: Conferences and Workshops ...........................................................................51

Appendix D: Calibration Services ........................................................................................54

Appendix E: Standard Reference Materials ..........................................................................58
iv Electronics and Electrical Engineering Laboratory

WELCOME

The Optoelectronics Division is a group of about 60 scientists, engineers, and support staff who 

work to improve the measurement infrastructure for the optoelectronics industry. Herein, you 

will fi nd both brief descriptions of our program areas and examples of some of our research, 

development, and metrology goals. More current information is available on our web site at 

www.boulder.nist.gov/div815/. Please contact us if we can be of assistance.

We take metrology seriously. In optoelectronics, as in many other fi elds, it is a key part of the 

industrial infrastructure that establishes competitiveness. Consistently specifi ed products are 

essential in fair trade, and measurements are a key element in effi cient manufacturing. The cost 

of measurements often ranges between 10 % and 30 % of the cost of producing a product. So 

while the optoelectronics industry, along with many other high technology fi elds, continues to 

struggle, advancing the fi eld of optoelectronics metrology remains an important task. 

We maintain the U.S. national standards for laser power and energy measurements (see Appendix D) and use them to provide the broadest range of laser calibration capabilities available 

anywhere. Each year we perform over 200 calibrations of power- or energy-measuring instruments for more than 50 customers. We also provide artifact calibration standards, which we 

call Standard Reference Materials, for over a dozen parameters (see Appendix E for details). 

These components provide customers with the capability of performing periodic instrument 

calibrations traceable to national standards in their own laboratories.

We are developing new tools and techniques for measurements in the rapidly advancing fi eld 

of nanotechnology and quantum optics. We develop measurement techniques for components 

and subsystems that can be used online and in situ in the manufacture of optoelectronic materials. We perform measurements to provide reference data on the optical properties of important 

optoelectronic materials. And we work closely with major standards-developing organizations, 

especially the Telecommunications Industry Association (TIA), the Video Electronics Standards 

Association (VESA). the International Electrotechnical Commission (IEC), and the International 

Organization for Standards (ISO), in developing industry standards. 

Our intent is to be the preeminent source of optoelectronics metrology in the world. We strive 

to provide the best optoelectronic measurement services possible and perform the research 

and development that best enhances measurement sciences in optoelectronics. If you have any 

suggestions on how we can improve or how we can serve the industry better, please let me 

know.

Kent Rochford

Chief, Optoelectronics Division

National Institute of Standards and Technology

(303) 497-5342

http://www.boulder.nist.gov/div815

rochford@boulder.nist.gov
Optoelectronics Division v 

ABOUT THE OPTOELECTRONICS DIVISION

MISSION

The mission of the Optoelectronics Division is to provide the optoelectronics industry and its 

suppliers and customers with comprehensive and technically advanced measurement capabilities and standards, and traceability to those standards.

HISTORY

The Division is located in Boulder, Colorado, as a part of the NIST Boulder Laboratories. It 

was established in 1994, succeeding an earlier NIST organizational unit, the Optical Electronic 

Metrology Group of the Electromagnetic Technology Division. The Division’s roots extend to 

the fi rst NIST (NBS) work on optoelectronics—research begun in the early 1960s to develop 

techniques for measuring the output power or energy of a laser. Since the late 1960s, NIST 

research on measurement and standards to support the development and application of lasers 

has been centered in the Boulder Laboratories. Research related to optical communications was 

added in the mid-1970s. Research in nanophotonics began in the 1990s, and this now represents 

more than half of the Division’s effort. 

ORGANIZATION

The Division is organized into three Groups. Two Groups, the Sources, Detectors and Displays 

Group and the Optical Fiber and Components Group, focus on the characterization of lasers, 

detectors, and other optoelectronic components. The third, the Optoelectronic Manufacturing 

Group, focuses on measurements that can lead to more effi cient manufacturing of optoelectronic 

materials and components, and has signifi cant efforts in nanoscale optoelectronic devices.

RESEARCH AND SERVICES

Most of the research performed in the Division is conducted either with NIST-appropriated 

funds or under contract to other U.S. government agencies. Results are typically placed in the 

public domain through publication in the open literature. Some results become the subject 

of patents, and are available for license. The Division also conducts proprietary research in 

collaboration with industry and universities through Cooperative Research and Development 

Agreements (CRADAs). 

The Division and its predecessor organizations have been providing calibration services for the 

characterization of lasers and detectors since 1967, and each year conducts over 200 calibrations 

for about 50 customers. It also provides the industry with standard reference materials, which 

are artifact standards that can be used by customers to calibrate their own instrumentation. 

The Division maintains close contact with the optoelectronics industry through major industry 

associations, including the Optoelectronics Industry Development Association (OIDA), the 

Lasers and Electro-optics Manufacturer’s Association (LEOMA), and the Council for Optical 

Radiation Measurements (CORM). Division staff members represent NIST to the major domestic and international standards organizations active in optoelectronics — the Telecommunications Industries Association (TIA), the International Electrotechnical Commission (IEC), the 

International Organization for Standardization (ISO), Society for Information Display (SID), 

and the American National Standards Institute (ANSI) — and provide impartial technical 

expertise in their negotiations. 
vi Electronics and Electrical Engineering Laboratory

OPTOELECTRONICS DIVISION STAFF

DIVISION OFFICE 815.00

Name Extension*

ROCHFORD, Kent B., Chief 5285

SMITH, Annie J., Secretary 5342

McCOLSKEY, Kathy S., 

Administrative Offi cer 3288

CASE, William E. (CTR) 3741

LOMAX, John, Secretary 3842

GORMAN, Mary., Secretary 4384

SOURCES, DETECTORS AND DISPLAYS (815.01)

DOWELL, Marla L. (GL) 7455

BOYNTON, Paul A. (PL) (301) 975-3014

CROMER, Christopher L. 5620

GILBERT, Katie 4884

HADLER, Joshua A. 4451

HALE, Paul D. (PL) 5367

JARGON, Jeffrey 4961

KEENAN, Darryl A. 5583

KELLEY, Edward F. 4599

LEHMAN, John H. (PL) 3654

LEONHARDT, Rodney W. 5162

LI, Xioyu 3621

LIVIGNI, David J. 5898

RAMADURAI, Krishna (GR) 4977

STREET, Lara (CTR) 4969

VAYSHENKER, Igor 3394

WEPMAN, Joshua (CTR) 5409

YANG, Shao 5409

OPTICAL FIBER AND COMPONENTS (815.03)

ROCHFORD, Kent B. (Act.GL) 5285

CODDINGTON, Ian (NRC PD) 4889

DENNIS, Tasshi 3507

DRAPELA, Timothy J. 5858

DYER, Shellee D. 7463

ESPEJO, Robert J. (PREP Grad) 7630

ETZEL, Shelley M. 3287

NEWBURY, Nathan R. (PL) 4227

SWANN, William C. 7381

WILLIAMS, Paul A. (PL) 3805

OPTOELECTRONIC MANUFACTURING (815.04)

HICKERNELL, Robert K. (GL) 3455 

BERTNESS, Kristine A. (PL) 5069

BLANCHARD, Paul (CTR) 4799

BRILLIANT, Nathan (GR) 4800

CHISUM, Jonathan (PREP-G) 4986

CLEMENT, Tracy 3052

DIETLEIN, Charles (GR) 4843

FENG, Ming Ming (GS) 4808

GERRITS, Thomas (CTR) 4661

GREENE, Marion (CTR) 4579

GROSSMAN, Erich N. 5102

GRUBER, Stephen (PREP-G) 4913

HADFIELD, Robert (GR) 5309

HARVEY, Todd 3340

LITA, Adrianna (CTR) 4608

MANSFIELD, Lorelle (PREP-G) 4793

MIGACZ, Justin, PREP-UG) 4835

MIRIN, Richard P. (PL) 7955

NAM, Sae Woo (PL) 3148

ROSHKO, Alexana 5420

ROURKE, Devin (PREP-UG) 4908

ROWE, Mary A. (CTR PD) 7879

SANDERS, Aric (CTR) 4731

SANFORD, Norman A. (PL) 5239

SCHLAGER, John B. 3542

SILVERMAN, Kevin L. 7948

STEVENS, Martin (CTR PD) 4740

SU, Mark 7368

Legend:

CTR = Contractor

CTR PD = Contractor Post-doctoral

GL = Group Leader

GS = Guest Scientist

PD = Post-doctoral Appointment

PREP PD = PREP Post-doctoral

PL = Project Leader

* Telephone numbers are (303) 497-XXXX,

with the four-digit extension given after the name
Optoelectronics Division 1

LASER RADIOMETRY

Technical Contact:

John Lehman

Staffi ng (FY06): 

7 professionals 

2 research associates

GOALS

Develop measurement methods and standards for 

characterizing laser sources and detectors used with 

laser radiation spanning in wavelength coverage 

from ultraviolet excimer lasers to mid-infrared 

lasers. Develop and maintain measurement services for laser power and energy, optical-fi ber 

power, and related parameters (spectral responsivity, linearity, etc.). 

CUSTOMER NEEDS

Accurate characterization of optoelectronic sources 

and detectors is important in the development and 

use of industrial technologies such as lightwave 

telecommunications, laser-based medical instrumentation, materials processing, photolithography, 

data storage, and laser safety equipment. The 

Laser Radiometry Project focuses on selected critical parameters intrinsic to sources and detectors, 

especially the calibration of optical-fi ber power 

meters and laser power or energy meters at commonly used wavelengths and powers or energies. 

In addition, special test measurements are available for linearity, spectral responsivity, and spatial 

and angular uniformity of laser power meters and 

detectors. Project members participate in national 

and international standards committees developing standards for laser safety, laser radiation, and 

optical-power-related measurements. They extend 

and improve source and detector characterizations, 

including development of low-noise, spectrally 

fl at, highly uniform pyroelectric detectors; highaccuracy transfer standards for optical-fi ber and 

laser power measurements; and advanced laser 

systems for measurements of laser power and 

energy. 

The Project supports research on new standards 

and measurement methods for both continuous 

wave and pulsed-laser measurements. Accurate 

measurement methods and standards for characterizing pulsed-laser sources and detectors pose 

particular research challenges and are critical in a 

number of industrial applications. Project efforts 

in the pulsed-laser area include development work 

in standard detectors, calibration services, and 

advising customers on in-house measurement capabilities. The bulk of our work in the pulsed-laser 

area is concentrated on ultraviolet (UV) excimer 

lasers and to the IR Q-switched lasers. Industrial 

applications for pulsed lasers include semiconductor manufacturing, metal fabrication, cutting, and 

welding with Q-switched IR lasers. In addition, 

these lasers are used in military settings for target 

designation and range fi nding.

TECHNICAL STRATEGY

Meeting the needs of the laser and optoelectronics 

industries and anticipating emerging technologies 

requires investigation and development of improved measurement methods and instrumentation 

for high-accuracy laser metrology over a wide 

range of powers, energies, and wavelengths.

ACCURACY OF CALIBRATION SERVICES

NIST has historically used electrically calibrated 

laser calorimeters to provide traceability to the SI 

units for laser power and energy. In addition, we 

have a measurement capability based on a LaserOptimized Cryogenic Radiometer (LOCR) that 

improves the accuracy of measurement of laser 

power by an order of magnitude as compared to 

electrically calibrated radiometers. To meet the 

increasing demands for higher accuracy over a 

larger range of optical power and wavelength, it 

is necessary to improve the accuracy of calibration services through the development of better 

transfer standards that are traceable to the LOCR. 

We are also developing the next generation primary 

standards to bridge the gap between classical and 

quantum laser radiometery.

STANDARDS FOR OPTICAL FIBER POWER

MEASUREMENTS

The continuing development of new optical-based 

telecommunications systems has led to demands 

for higher performance and higher accuracy for 

optical-fi ber power meter characterization and calibration. Many of these new systems being developed demand higher power for optical-fi ber power 

meter (OFPM) characterization and calibration. 

As much as several watts in fi ber is being used in 

systems to pump laser sources for new applications. 

In addition, the Department of Defense (DOD) is 

accelerating the implementation of optical fi ber in 

many of its new weapons systems. By developing 

improved standards for optical fi ber power and by 

developing instrumentation to accurately quantify 

the uncertainties of the new standards, we can meet 

these demanding requirements. 
2 Electronics and Electrical Engineering Laboratory

NEW COATING TECHNOLOGIES FOR LASER

STANDARDS

Single-wall (SWNT) and multiwall (MWNT) carbon nanotubes may form the basis of the next generation of absorber coatings for thermal detectors 

for high-accuracy optical and thermal radiometry, 

particularly for high-energy and ultraviolet laser 

radiometry. Currently, all of the primary standards 

in the U.S. and elsewhere that are used to establish 

traceability to SI radiometry units are based on 

thermal detectors. All of these devices employ 

some form of thermal absorber coating such as a 

carbon-based paint or diffuse metal coating (e.g., 

gold-black). We are developing carbon nanotube 

coatings for thermal detectors as a highly desirable 

advance over current state of the art. These coatings must be resistant to damage and aging while 

maintaining desirable optical and thermal (spectral, spatial, directional uniformity, high thermal 

conductivity) properties. We have recently demonstrated optical detectors with absorptive coating 

consisting of SWNTs, and MWNTs. In addition we 

have undertaken the evaluation of damage properties of carbon nanotubes and carbon nanotube 

composites on a variety of detector platforms

PLAN: Demonstrate the next generation of coatings 

for laser power and energy measurement standards 

based on carbon nanotubes (CNTs). The coatings will 

allow us to expand existing measurement services to 

include UV laser measurements and high-power laser 

diode measurements. Demonstrate thermal detectors 

suitable for the range of laser wavelengths served by 

our calibration services (0.157 μm to 10.6 μm). 

Diode based (left) and pyroelectric (right) transfer 

standards for optical fi ber power measurements.

CHARACTERIZATION OF HIGH-EFFICIENCY

DIODE SOURCES

We are expanding our calibration services to include measurements of high-effi ciency laser diode 

sources. These measurements include evaluations 

of the thermal, optical, and electrical properties 

of the diode sources. We have developed a watercooled optical radiometer that is capable of accurate 

optical power measurements up to approximately 

100 W. This work supports ongoing developments 

of high-power diode sources for diode-pumped 

lasers for a variety of applications.

PLAN: Provide measurement services for the 

characterization of high-power diode sources, e.g., wall 

plug effi ciencies and laser beam profi les. 

Laser induced damage testing of thermal detector 

coatings. The orange glow is that of single wall 

nanotubes (black circular area) exposed to ~ 1 kW/cm2

at 10.6 μm.

Laser damage of silica based optical absorber (black 

paint) indicated by cracks and white glassy surfaces.
Optoelectronics Division 3

INTERNATIONAL AND NMI 

COLLABORATION

Along with AIST, METAS and PTB, we have undertaken intercomparisons of optical fi ber power 

measurements in terms of absolute responsivity and 

linearity. NPL and NIST have recently documented 

the outcome of several ongoing collaboration efforts to establish improved transfer standards for 

infrared radiometry. As part of this work we were 

the fi rst to demonstrate a multiwall carbon nanotube 

coated detector for spectral responsivity measurements at wavelengths greater than 10 μm. We 

also recently delivered several optical detectors to 

METAS to establish the basis of their optical fi ber 

power meter calibrations, particularly at common 

optical communications wavelengths 

PULSED-TO-CW TRANSFER STANDARDS

There is a need for higher-accuracy calibration of 

laser-energy meters for pulsed-laser radiation from 

3 μJ to 30 mJ with 8 ns to 20 ns pulse duration, and 

pulse repetition rates from 1 Hz to 20 Hz. Currently 

the uncertainty of these measurements using commercially available meters is at the level of 5 % 

or higher. Traceability through comparisons using 

the more accurate LOCR are not possible because 

of the inabilities of existing transfer standards 

to accurately measure both cw and pulsed laser 

radiation. We are developing a transfer standard 

that will provide traceability to both pulsed and cw 

NIST primary standards (including the LOCR and 

Q-series calorimeter). 

Wall plug effi ciency of 980 nm diode bar.

PLAN: To improve, by at least 

a factor of fi ve, the uncertainty 

capability of a transfer standard 

traceable to the LOCR in cw 

operation, but used normally in 

measurements involving pulsed 

laser energy with the Q-series 

standards. This project is sponsored 

by the US Army and Navy to 

improve measurements related to 

the evaluation of range fi nders and 

target designator systems.

BLUE/UV LASER

METROLOGY

We have initiated a program to 

optimize the LOCR and to develop appropriate transfer standards for low-power cw laser measurements at laser 

wavelengths shorter than 400 nm in support of the 

detection of chemical and biological aerosols. We 

recently demonstrated a UV calibration of a NIST 

transfer standard by means of intercomparison with 

the C-series calorimeter and the Laser Optimized 

Cryogenic Radiometer, thus extending our range 

of calibration services to 375 nm. This work will 

continue as UV laser diodes (expected by OIDA to 

be a $4B industry by 2010) at shorter wavelengths 

(255 nm to 375 nm) become available. We recently reported to the Council for Optical Radiation 

Measurements that UV photodiodes exhibit large 

degrees of nonlinearity, depending on laser pulse 

width, energy and frequency, which is undesirable 

for most measurement applications. This information is very valuable for making improved laser 

systems and optimizing new laser applications.

PLAN: Pursue new technologies to improve our 

measurement capability, including improved transfer 

standards, improved coatings for thermal detectors, 

and optimization of the LOCR for blue and UV laser 

power measurement traceablility.

Nonlinearity of UV photodiodes for pulsed laser measurements at three 

different bias voltages.
4 Electronics and Electrical Engineering Laboratory

METROLOGY FOR EYE-SAFE LASER

TARGET SYSTEMS

Recently there has been increasing demand to 

extend the wavelength range of laser target ranging and designation systems to the eye-safe laser 

regime. These laser systems provide positional 

information, such as distance and incident angle, 

for use in locating targets. There is a need to extend 

existing pulsed Nd:YAG laser power and energy 

calibration services to include measurements at 

1.55 μm and to reduce the overall uncertainty associated with these measurements. In addition, there 

is need for high-power attenuators both at 1 μm and 

1.5 μm. Commercially available laser attenuators 

do not have the required durability and linearity 

when used with the hundreds of millijoules from 

these high-power Q-switched lasers.

PLAN: Develop capabilities for measurements of high 

pulse energy at 1.5 μm. Design, build, and characterize 

an improved calibration service for measurements of 

attenuators for use with Q-switched Nd:YAG lasers. 

ACCOMPLISHMENTS

Completed the fi rst phase of participation in 

a DARPA sponsored program to evaluate the wall 

plug effi ciency of high effi ciency diode sources. 

As part of this, we have developed a novel fl owing 

water power meter suitable for measuring optical 

power from diode sources and that is scalable to 

kW/cm2. 

Evaluated a bulk form of single-wall carbon 

nanotubes (SWNTs) as a coating for future optical standards. The absorption effi ciency of SWNT 

coatings is greater than that which was expected 

for the bare (uncoated) detector. Furthermore, the 

detector’s response (and hence the absorption of the 

SWNT coatings) varies by less than 1 percent as a 

function of wavelength from 600 nm to 1800 nm. 

The nanotube-based coatings do not compromise 

the detector performance. These encouraging 

results indicate that once an optimized SWNT 

coating has been achieved, the expected detector 

responsivity of a SWNT-coated standard should 

surpass the performance of current gold-black 

coated standards. The resulting SWNT-coated 

detector will be a more robust, spectrally fl at optical standard.

Completed intramural comparison of NIST 

laser and optical fi ber power calibration services. 

The comparison demonstrated equivalence of NIST 

absolute responsivity measurement services at laser 

wavelengths of 633, 850, 1060, 1310, and 1550 nm 

use of NIST check standards. The results indicated 

■

■

■

that the responsivity of the check standards, as determined independently by the various calibration 

services, agreed to within the published expanded 

uncertainties ranging from 0.02 % to 1.24 %. 

Demonstrated that the accuracy of optical-fi -

ber power measurements depends on the type and 

manufacturer of the fi ber connector. A comparison 

of absolute responsivity measurement results for 

four different optical-fi ber power meter standards 

at 850 nm, 1310 nm and 1550 nm for fi ve different 

types of fi ber connectors (FC, ST, biconic, SC, and 

SMA) produced by three different manufacturers 

yielded reproducible offsets as large as 4.6 % in 

detector calibration factors due to fi ber connector 

types. 

Established a measurement system for characterizing detector nonlinearities at 193 nm. This 

service is an inexpensive alternative to customers 

who are more concerned with the relative, rather 

than the absolute, response of their detectors. The 

primary reason for its lower cost is the reduced 

turnaround time; a measurement of linearity takes 

only one-third the time of a full calibration. 

Completed an internal comparison of all three 

excimer laser calorimeters at 157 nm, 193 nm, and 

248 nm. The 193 and 248 nm comparisons show 

agreement to less than 0.3 %.

CALIBRATIONS

The Optoelectronics Division provides calibration 

services for laser and optical-fi ber power at many 

wavelengths and power levels from the ultraviolet 

and far-IR spectral regions, and from picowatt to 

kilowatt power levels. See Appendix D for a list 

of available calibrations. 

Current information for fees and contact is available at http://ts.nist.gov/ts/htdocs/230/233/calibrations/optical-rad/laseroptoelectronic.htm

STANDARDS COMMITTEE

PARTICIPATION

American National Standards Institute: John H. 

Lehman is a member of committee Z136, subcommittees SSC-01 and SSC-04, which deal with safe 

use of lasers.

Telecommunications Industry Association: Igor 

Vayshenker is a member of subcommittee FO-4.9, 

which deals with metrology and calibration.

International Standards Organization: Marla L. 

Dowell is a member of working group TC 172/SC 

9/WG 1 and WG6, which deals with terminology 

■

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Optoelectronics Division 5

and test methods for lasers, and a member of working group TC 172/SC 1/WG 1 and WG6, which 

deals with general optical test methods.

Optics and Electro-Optics Standards Council 

(OEOSC): Marla L. Dowell is Chairperson-elect 

and IEEE-LEOS representative. 

U.S. National Committee/International Electrotechnical Commission: John H. Lehman is a 

member of technical committee TC76, working 

groups 1 and 3, which deal with laser radiation 

measurement and safety.

RECENT PUBLICATIONS

E. Theocharous, R. Deshpande, A. C. Dillon, and J. Lehman, 

“Evaluation of a pyroelectric detector with a carbon multiwalled 

nanotube black coating in the infrared,” Appl. Opt., Vol. 45, pp. 

1093–1097 (2006).

K. Gilbert, A. Dillon, J. Blackburn, J. Lehman, “Toward rapid 

and inexpensive identifi cation of carbon nanotubes,” Appl. Phys. 

Lett., Vol. 88, 143122 (2006).

A. C. Dillon, A. H. Mahan, R. Deshpande, J. L. Alleman, J. L. 

Blackburn, P. A. Parillia, M. J. Heben, C. Engtrakul, K. E. H. 

Gilbert, K. M. Jones, R. To, S -H. Lee, J. H. Lehman, “Hot-wire 

chemical vapor synthesis for a variety of nano-materials with 

novel applications,” Thin Solid Films, Vol. 501, pp. 216–220 

(2006).

J. H. Lehman, R. Deshpande, P. Rice, B. To, A. C. Dillon, 

“Carbon multi-walled nanotubes grown by HWCVD on a 

pyroelectric detector, Infrared Physics and Technology, Vol. 

47, pp. 246–250 (2005).

H. Laabs, D. A. Keenan, S. Yang, and M. L. Dowell, “Measurement of detector nonlinearity at 193 nm,” Appl. Opt., Vol. 44, 

No. 6, pp. 841–848 (2005).

J. H. Lehman, A. C. Dillon, C. Engtrakul, “Carbon nanotubes 

based coatings for laser power and energy measurements using 

thermal detectors,” Conference on Lasers and Electro-Optics, 

OSA Technical Digest (Optical Society of America, Washington 

DC) (2004).

J. H. Lehman, I. Vayshenker, D. J. Livigni, J. Hadler, “Intramural comparison of NIST laser and optical fi ber power 

calibrations,” J. Res. Natl. Inst. Stand. Technol., Vol. 109, pp. 

291–298 (2004). 

D. L. Livigni, “High accuracy laser power and energy meter 

calibration service,” NIST Spec. Publ., pp. 250–62 (2003).

J. H. Lehman and C. Pannell, “Position and temperature dependence of pyroelectricity in domain-engineered stoichiometric 

and congruent LiTaO3,” Ferroelectrics, Vol. 296, pp. 39–55 

(2003).

J. H. Lehman, E. Theocharous, G. Eppeldauer, C. Pannell, 

“Gold-black coatings for freestanding pyroelectric detectors,” 

Meas. Sci. Technol., Vol. 14, pp. 916–922 (2003).

I. Vayshenker, H. Haars, X. Li, J. H. Lehman, and D. J. Livigni, 

“Optical-fi ber power meter comparison between NIST and 

PTB,” J. Res. Natl. Inst. Stand. Technol., Vol. 108, pp. 391–394 

(2003)

J. H. Lehman and C. L. Cromer, “Optical trap detector for 

calibration of optical fi ber power meters: coupling effi ciency,” 

Appl. Opt., Vol. 41, No. 31, pp. 6531–6536 (2002).

J. H. Lehman, A. M. Radojevic and R. M. Osgood, Jr., “Domainengineered thin-fi lm LiNbO3 pyroelectric-bicell optical detector,” IEEE Phot. Tech. Lett., Vol. 13, pp. 851–853 (2001).

C. L. Cromer, M. L. Dowell, R. D. Jones, D. A. Keenan, and S. 

Yang, “A primary standard for 157 nm excimer laser measurements,” in AIP Conf. Proc., Characterization and Metrology 

for ULSI Tech., No. 683, pp. 409–412 (2003).

H. Laabs, R. D. Jones, C. L. Cromer, M. L. Dowell, V. Liberman, “Damage testing of partial refl ectors for 157 nm laser 

calorimeters,” Proc., SPIE, Laser-Induced Damage in Optical 

Materials 2001, Vol. 4679, pp. 332–338 (2002).
6 Electronics and Electrical Engineering Laboratory

DISPLAY METROLOGY

Technical Contact: 

Paul Boynton

Staffi ng (FY06):

2 professionals

GOALS

By merging television, computers, and telecommunications into advanced digital video and computer 

systems, manufacturers are providing new services 

for education, engineering, manufacturing, robotics, entertainment, medicine, defense, security, 

transportation, publishing, advertising, banking, 

and government. A critical element in this convergence is the use of electronic displays in an 

interchangeable fashion in all of these systems. 

Although displays are manufactured primarily offshore, U.S. manufacturers are the largest consumer 

of displays. To facilitate worldwide commerce in 

displays, a well-defi ned method for specifi cation 

and verifi cation of display quality is needed to ensure that the display will work under the necessary 

lighting conditions. NIST is working with industry 

standards-developing organizations to ensure such 

equity in the marketplace by developing the metrology base for displays.

CUSTOMER NEEDS

The United States is a major buyer of electronic 

displays for computer, consumer, automotive, 

medical, telemedicine, and avionics use. Sound 

metrology is urgently needed in this highly competitive environment of new and emerging display 

technologies. Furthermore, universally recognized 

and accepted standards and measurement methods 

are needed to provide customers with tools to use in 

choosing the best display for their applications.

TECHNICAL STRATEGY

This project is concerned with display metrology 

in general and involves numerous ongoing tasks. 

However, we focus our research on specifi c issues 

identifi ed by industry as particularly important.

REFINEMENT OF MEASUREMENT

PROCEDURES

We are developing and refi ning measurement procedures in support of ongoing electronic display 

metrology, and applying the results in the development of national and international standards for 

characterization of fl at panel displays.

PLAN: To support the revision of the Video Electronics 

Standards Association (VESA) Flat Panel Display 

Measurement Standard (FPDM) through the 

development of new measurement methods and written 

standards. 

CHARACTERIZATION OF REFLECTION

COMPONENTS

The measurement systems and methods to characterize the three components of refl ection (Lambertian, specular, and haze) associated with displays 

are being developed. Development and implementation of robust methods are needed to characterize 

display refl ection performance under actual conditions, for example, the readability of automotive 

displays in high ambient light conditions. 

PLAN: Analyze and publish the success of our 

variable-radius-source method is in capturing the 

specular component and haze peak in making robust 

refl ection measurements. (This is a collaborative effort 

with NIST’s Optical Technology Division). Develop 

methods to characterize displays for sunlight readability 

applications.

Variable Radius Source Method for Isolation of specular (ζ) and haze (h) refl ection components.

NEW INTERLABORATORY COMPARISON

STANDARDS

To determine the measurement capabilities of 

participating laboratories in an interlaboratory 

comparison effort, this project has developed a 

multifi lter source-display measurement assessment 

transfer standard (DMATS) that can be shared 

among participating laboratories. The combination 

of all the targets will provide a benchmark of the 

capabilities of participating laboratories in making 

conventional luminance and color measurements. 

Typically, light-source calibrations involve only a 

white point. These new standards include the white 

point and much of the color gamut. A simplifi ed 

version of this apparatus employing fi lter wheels 

instead of a fi lter array has been developed. This 

apparatus is referred to as the gamut assessment 

standard (GAS). The DMATS/GAS solution is es-
Optoelectronics Division 7

sential to resolving issues of color transportability 

in E-commerce by assuring that the color measurement instrumentation employed is suffi ciently reliable to discriminate color differences. This program 

is conducted in collaboration with the Physics 

Laboratory’s Optical Technology Division.

PLAN: Investigate the design of a robust light source 

for using in the gamut assessment standard (GAS) 

and conduct general interlaboratory comparisons on a 

regular basis with industry. 

Gamut Assessment Standard (GAS). 

DISPLAY CHARACTERIZATION OF THERMAL

IMAGERS FOR FIRST RESPONDERS

Thermal imagers used by fi refi ghters and other fi rst 

responders incorporate visual electronic displays as 

a key component. In collaboration with the Fire 

Research Division, we are developing a series of 

measurement procedures to assist manufacturers 

and end users in evaluating system performance.

PLAN: Develop basic procedures for measuring 

grayscale, resolution, and uniformity for incorporation 

into standards (in collaboration with the BFRL Fire 

Research Division and the PL Optical Technology 

Division).

DISSEMINATION OF INFORMATION

A key component of our work is in the education of 

our customers. We seek to provide our customers 

with the information that they need through standards activities, conference presentations, invited 

tutorials, and publications. As a part of this effort, 

we are developing a one-week hands-on course 

on good display metrology practices. This course 

will be offered on an ongoing basis at the NISTBoulder campus.

PLAN: Continue to offer in-house courses on 

display metrology providing hands-on laboratory 

measurements. We plan to teach the in-house course 

on display metrology at least once per year and as 

frequently as four times per year. 

METROLOGY FOR MEDICAL IMAGING

APPLICATIONS

Critical diagnostic and clinical standards and techniques are required for the evaluation of medical 

images, medical imaging devices (includes both 

image acquisition devices such as digital cameras 

and microscopes, and display devices), the evaluation of computer assisted diagnostic tools, and 

the effects of compression on image quality. The 

lack of standards is becoming an increasingly 

critical roadblock as new medical diagnostic and 

imaging techniques become available and as new 

or improved display technologies come into use. 

Diagnosticians in many areas have integrated new 

imaging devices into their practice. Many doctors 

take images with them for viewing in the comfort 

of their homes. Images are routinely emailed to 

consulting physicians without regard to whether the 

displays on which they are viewed meet minimum 

performance standards. Images may be compressed 

for storage or for transportation across wireless systems. Improved rendering of transmitted medical 

images will lead to lower cost healthcare services, 

especially for remote, sparsely populated regions 

of the U.S.

PLAN: Adapt sunlight readability metrics to measure 

color and small area contrast of handheld devices for 

medical imaging applications. 

Measurement apparatus for testing probes used to 

characterize medical displays. Inset shows the tip 

of the probe pointing at the illuminance head (small 

white disk) that measures the back refl ection from the 

probe.
8 Electronics and Electrical Engineering Laboratory

ACCOMPLISHMENTS

Four hands-on short courses have been held at 

NIST in FY06, all receiving positive reviews. We 

plan to continue to offer this course up to four times 

a year. In addition, three invited seminars on Flat 

Panel Display Measurements and Standards were 

presented: the Society for Information Display 

(SID) 2006 International Symposium, the SID 

Americas Display Engineering and Applications 

Conference, and the International Broadcasting 

Convention (IBC) 2006. Emphasis was placed 

on (1) techniques being as important as good 

equipment, and (2) refl ection metrology is more 

complicated than currently envisioned by the 

display industry.

Beta testing of the gamut assessment standard 

(GAS) was begun with participating laboratories.

Developed proposed metrics for characterizing 

display performance for daylight measurements, 

and submitted paper to the Journal of the SID.

As part of a multi-Laboratory effort, developed 

a relationship with the telemedicine community 

to explore ways NIST can help address some of 

their measurement needs. This resulted from a 

series of USMS Workshops on imaging metrics 

in telemedicine.

Evaluated, in collaboration with the Fire 

Research Division, the effectiveness of present 

methods for evaluating the performance of thermal 

imagers used by fi rst responders.

COLLABORATIONS

In addition to the collaborations that follow 

naturally from standards activities (see below) 

and other routine advisory roles, there are some 

specifi c collaborations of interest that are currently 

underway:

As described above, the Fire Research Division, 

the Optical Technology Division and the Display 

Metrology Project are working together to develop 

a series of tests to evaluate the system performance 

of thermal imagers used by fi rst responders.

We are working with the Food and Drug Administration (FDA) on making small-area measurements of radiological images using stray-lightreducing probes for small-area measurements of 

luminance.

Robust and meaningful refl ection measurements 

for the evaluation of sunlight readability of displays are being developed with DuPont Displays, 

E-Ink,, Qualcomm, Kodak, and Army Research 

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Laboratory (in conjunction with the US Display 

Consortium).

A multi-OU effort is underway, working with the 

American Telemedicine Association, to explore 

additional ways NIST can support the telemedicine community. This effort is an outgrowth of 

a series of USMS Workshops on image quality in 

telemedicine.

STANDARDS COMMITTEE

PARTICIPATION

Video Electronic Standards Association (VESA) 

Display Metrology Task Group: Edward F. Kelley, former chair of this group, currently serves 

as editor of the Flat Panel Display Measurement 

(FPDM) Standard, a scientifi c and comprehensive 

document, prepared with signifi cant input from 

NIST, to address display metrology. Dr. Kelley is 

responsible for creating and implementing all of 

the patterns used by the standard in addition to his 

editorial responsibilities for the next generation 

document (FPDM3) and associated measurement 

methods.

International Organization for Standardization 

TC159/SC4/WG2 Visual Display Requirements: 

Paul A. Boynton is a member of this committee, 

which is developing a revision of all of its display 

standards. NIST is coordinating the development 

and evaluation of the metrology sections.

International Electrotechnical Commission TC 

110/PT 62341-6: Organic Electroluminescent 

Displays - Part 6: Measuring Methods of Organic 

Light-Emitting Displays. Paul A. Boynton is 

providing technical expertise in the development 

of this standard.

Society for Automotive Engineers J 1757 Standard 

Metrology for Vehicular Flat Panel Displays: Edward F. Kelley is a member and is providing support in the evaluation of refl ection measurements 

and developing appropriate effi ciency metrics.

Council for Optical Radiation Measurements CR5 (Flat Panel Displays). All project personnel are 

members; Paul A. Boynton serves as committee 

chair. The committee is currently evaluating the 

DMATS and GAS program

Society for Information Display Defi nition and 

Standards Committee. All project personnel are 

members; Paul A. Boynton serves as committee 

chair.
Optoelectronics Division 9

RECENT PUBLICATIONS

P. A. Boynton and E. F. Kelley, “Comparing methodologies 

for determining resolution from contrast in projection display 

systems,” Proc. SPIE, Vol. 5740, No. 116 (2005).

E. F. Kelley, M. Lindfors, and J. Penczek, “Daylight and sunlight 

display readability measurement methods” Council for Optical 

Radiation Measurements Conference (2005).

E. F. Kelley, “Challenges in automotive display standards” 

Council for Optical Radiation Measurements Conference

(2005).

E. F. Kelley, “Variable-radius source method to separate specular 

component from haze peak” Proc. SID Americas Second Display 

Engineering and Applications Conference, pp. 1–4 (2005).

E. F. Kelley, “What do the specifi cations mean?,” Proc. SID 

Americas First Display Engineering and Applications Conference, pp. 15–18 (2004).

P. Boynton, “Tools and diagnostics to assess and improve 

projection display metrology capabilities,” Proc. SID Americas 

First Display Engineering and Applications Conference, pp. 

15–18 (2004).

E. F. Kelley, “Flat-panel-display measurement techniques and 

concerns,” 2004-SID International Symposium Seminar Lecture 

Notes, Society for Information Display, Seminar F-1, Vol. 2, 

pp. F-1/1-61 (2004).

P. Boynton, “The challenge to display metrology and standards: 

whom do you trust?” Workshop and Special Evening Session 

of the SID 24th International Display Research Conference, 

pp. 46–57 (2004).

E. F. Kelley, “Plotting the course of the next VESA fl at panel 

display measurements standard,” 2004-SID International Symposium Digest of Technical Papers, Society for Information Display, Invited Paper 7.1, Vol. 35, Book 1, pp. 78–81 (2004).

E. F. Kelley and J. Penczek, “Scalability of OLED fl uorescence 

in consideration of sunlight-readability refl ection measurements,” 2004-SID International Symposium Digest of Technical 

Papers, Society for Information Display, Paper P.54, Vol. 35, 

Book 1, pp. 450–453 (2004).

P. Boynton, “Methods for assessing display measurement 

capabilities,” Cockpit Displays XI, Proceedings of the SPIE, 

Vol. 5543, 311 (2004).

P. A. Boynton, E. F. Kelley, and J. M. Libert “Projection display 

metrology at NIST: measurements and diagnostics,” Liquid 

Crystal Materials, Devices, and Applications X and Projection 

Displays X, Proceedings of the SPIE, Vol. 5289, pp. 302–313 

(2004).

J. M. Libert, E. F. Kelley, P. A. Boynton, S. W. Brown, C. 

Wall, and C. Campbell, “A color gamut assessment standard: 

construction, characterization and interlaboratory measurement 

comparison,” Fourth Oxford Conference on Spectroscopy, SPIE,

Vol. 4826, pp. 146–164 (2003).

E. F. Kelley and A. Badano, “Characterization of luminance 

probe for accurate contrast measurements in medical displays,” 

NISTIR 6974, 15 pages (2003).

E. F. Kelley, “Sensitivity of display refl ection measurements to 

apparatus geometry,” 2002 SID International Symposium Digest 

of Technical Papers, Society for Information Display, Boston, 

MA, pp. 140–143 (2002).

E. F. Kelley, “Fundamentals of display metrology,” 2002 Society 

for Information Display International Symposium Short Course

S-3, 2002 SID International Symposium, Boston, MA, p. 205, 

May 19–24 (2002).
10 Electronics and Electrical Engineering Laboratory

HIGH-SPEED MEASUREMENTS

Technical Contact:

Paul Hale

Staffi ng (FY06): 

4 professionals

1 associate

GOALS

Provide advanced metrology, standards and measurement services relating to temporal properties 

of optical sources, detectors, and signals used in 

association with optoelectronic systems. 

The electro-optic measurement system, shown here being operated by Tracy Clement, measures an electrical 

pulse on a LiTaO3 wafer. De-embedding techniques 

are then used to determine the voltage generated by 

the photodiode being tested at its coaxial output connector. (© Geoffrey Wheeler)

CUSTOMER NEEDS

High-bandwidth measurements of both optical 

and electrical devices are needed to support optical communication systems that take advantage 

of the potential bandwidth of optical fi ber. Presently, systems are being installed that operate at 

modulation rates of 10 gigabits per second by use 

of time-division multiplexing (TDM). Research 

laboratories around the world are focused on developing the next generation of TDM systems at 

40 gigabits per second and higher. New methods 

are needed to accurately characterize the scalar and 

vector frequency response of high-speed sources, 

detectors, and instrumentation to three to ten times 

the system modulation rate. Burst-mode operation 

in asynchronous transfer mode networks requires 

additional characterization at very low frequencies. 

Increasingly tight tolerances in both digital and 

analog systems require new and improved measurements in both frequency- and time-domains with 

low uncertainty. 

High-speed measurements are needed in other areas 

as well. Microwave and wireless communications 

are also pushing to ever greater bandwidths by 

use of complicated modulation formats, while the 

instruments to measure these waveforms remain 

only loosely calibrated. This project leverages 

its expertise in both optical and electrical device 

characterization to cross disciplinary boundaries 

in the application of new measurement methods. 

For example, the intensive use of laser target 

designators and range fi nders by the armed forces 

requires traceable calibration standards for lowlevel peak pulse power and energy at 1064 nm 

and 1550 nm. 

TECHNICAL STRATEGY

We have developed a suite of highly accurate 

optoelectronic measurement systems for characterizing high-speed optoelectronic devices. Our 

optoelectronic techniques also allow calibration 

of electronic instrumentation with greater accuracy 

and bandwidth than electrical techniques. When 

correlations of error components are recorded, they 

can be used to give full waveform uncertainties in 

both the time domain and the frequency domain.

OPTOELECTRONIC VECTOR FREQUENCY

RESPONSE MEASUREMENTS TO 110 GHZ

NIST has developed highly accurate heterodyne 

techniques at 1319 nm and 1550 nm for measuring the scalar frequency response of detectors. 

Measurement services are available for modulation 

frequency-response transfer standards that consist 

of a photodiode combined with a microwave power 

sensor, and can measure this type of standard from 

300 kHz to 110 GHz or more at 1319 nm. We also 

have a service for calibrating the frequency-response magnitude of bare photodiodes to at least 

50 GHz. Calibration of bare photodiodes is more 

complicated because it requires calibrated microwave power and measured scattering-parameters. 

Optoelectronic phase response, when combined 

with the magnitude response, is called the vector response. The vector frequency response of 

a photoreceiver is the Fourier transform of its 

time-domain impulse response. Measurements 

of the vector response are required for the design 

of high-speed optoelectronic systems, but until 

recently there were no accepted standard methods 

for this measurement.
Optoelectronics Division 11

Researchers in the High-Speed Measurements 

Project, in collaboration with the Electromagnetics Division, the Statistical Engineering Division, 

and the Mathematical and Computational Sciences Division, have demonstrated time-domain 

techniques for measuring optoelectronic vector 

response with verifi able accuracy up to 110 GHz by 

use of electro-optic sampling (EOS). By developing these measurements our project is pioneering 

a new paradigm for time-domain measurements 

with frequency-domain calibrations. 

PLAN: Extend EOS capability to 400 GHz by use of 

on-wafer measurement techniques.

APPLICATIONS OF OPTOELECTRONIC

MEASUREMENTS

Optical communications analyzers and reference 

receivers used for measuring digital eye-patterns on 

optical signals have many similarities to electrical 

oscilloscopes, but also have advantages of their 

own. In particular, they can be calibrated over a 

very high bandwidth because they do not require 

band-limited microwave calibrations. 

Calibrated time-domain measurements, however, 

possess some unique problems. For example, we 

must develop methods for removing time-base 

distortions and deconvolving the oscilloscope 

response and impedance mismatch. Point-by-point 

uncertainty analysis in the time domain will enable 

industry to improve eye-pattern measurements 

and to quantify the performance of bit-error-ratio 

testers. 

Commercial equipment presently available for 

characterizing the phase dispersion and phase 

delay of optoelectronic receivers suffers from high 

uncertainty, limited bandwidth, and in some cases, 

unverifi ed calibrations, or calibrations that are not 

traceable to fundamental physical principles. Traceable vector frequency-response measurements are 

critical for characterizing balanced receivers that 

are needed for coherent optical communication 

applications.

PLAN: Provide calibrated pulse sources for 

instrumentation and component manufacturers that are 

traceable to fundamental units. Work with customers to 

disseminate this capability in a cost effective manner.

WAVEFORM METROLOGY

High-speed/high-bandwidth waveforms contain 

valuable information missed by current electronic 

measurement techniques that could be captured 

with new optoelectronic-based metrology. Waveform measurements verify signal fi delity and standard compliance for the design and qualifi cation 

of components and systems. However, current 

waveform test equipment is characterized only 

with single-parameter metrics, such as bandwidth 

or rise-time. Common equipment properties, such 

as loss, mismatch, modulation response, and jitter, 

which become signifi cant above a few gigahertz, 

are typically not corrected or characterized. In 

many cases, these limitations on waveform measurement equipment arise from a lack of comprehensive metrology. 

We are developing fundamentally new techniques 

and measurement services at bandwidths and risetimes currently unattainable, to verify waveforms 

for a wide range of applications (e.g., optical 

communications, high-speed microcircuitry, wireless communication, advanced radar, and remote 

sensing). This metrology will generate signifi cant 

savings in production costs stemming from false 

rejections of functioning devices due to inaccurate 

signal characterization.

PLAN: Develop accurate measurements of classical 

pulsed waveform parameters and extend to full 

waveform calibration using a covariance matrix-based 

approach.

Simulated eye mask test of a long random bit sequence 

transmitted by a fi ber-optic transceiver. The forbidden region in this pass/fail test is shown in the hashed 

region, surrounded by a 10 % guard band (margin). 

Although the simulated transceiver meets specifi cations, the frequency response and jitter errors in the 

oscilloscope measurement (top) cause the transceiver 

to fail the test as some samples fall into the guard 

band. The bottom graph shows the effect of calibrating 

and correcting the oscilloscope errors, clearly passing 

a component that would otherwise have been rejected.
12 Electronics and Electrical Engineering Laboratory

METROLOGY FOR EYE-SAFE LASER

TARGET SYSTEMS

Military systems involving laser trackers and 

target designators are converting to and/or adding a capability to operate at laser wavelengths of 

1.5 μm because of the eye-safe benefi ts. However, 

there are no commercial standards for measuring low-levels of pulsed laser power/energy in 

this wavelength region. Currently, pulsed laser 

standards are silicon-based and do not operate at 

wavelengths longer than 1.1 μm in the infrared, 

requiring the development of new instrumentation. 

We are developing new transfer standards, as well 

as the systems to calibrate them, capable of lowlevel pulsed power/energy laser measurement in 

the 1.5 μm wavelength region. These standards 

will be transitioned to meet Homeland Security 

requirements and military systems certifi cation. 

Calibrations will be traceable to national laser 

power/energy standards and supported by NIST.

PLAN: Provide customers with the capability to 

deconvolve radiometer impulse response for arbitrary 

laser pulse shapes. 

ACCOMPLISHMENTS

Recent advances in high-speed measurements 

have been a result of close collaborations with the 

Electromagnetic Division (EEEL) and with the 

Statistical Engineering and the Mathematical and 

Computational Sciences Divisions (ITL).

Developed an electro-optic sampling system 

to sample high-speed electrical waveforms on a 

coplanar waveguide with ultrashort laser pulses 

via the electro-optic effect. Standard microwave 

techniques are used to calibrate the response of 

a photoreceiver at its 1 mm electrical port that is 

physically removed from the sampling plane. 

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Accurately characterized the modulation 

response magnitude and phase of commercially 

available photoreceivers to 110 GHz, nearly three 

times the bit rate of 40 Gb/s optoelectronic systems. 

The frequency range of the calibration is limited 

only by the 1 mm coaxial connectors. The characterized photoreceiver has a bandwidth of about 80 

GHz; the signal-to-noise ratio of the measurement 

is greater than 150:1 at 110 GHz. 

Implemented a new slotted-line technique 

that uses electro-optic sampling to measure the 

impedance of coplanar waveguide terminations to 

facilitate on-wafer waveform measurements. This 

method has the advantage that it can be used to 

measure impedance into the terahertz range.

Demonstrated a calibrated on-wafer waveform 

measurement over a 200 GHz frequency range, with 

a point-by-point time-domain uncertainty analysis 

using the new slotted-line technique. Since the 

frequency range of this measurement was limited 

only by the bandwidth of the photodiode we used 

as an electrical pulse generator, we can potentially 

make calibrated waveform measurements into the 

terahertz regime, i.e., to pulse widths of less than 

1 ps.

Published a rigorous theory for calibrating the 

small-signal optoelectronic frequency response of 

photoreceivers and modulated sources by using an 

electrical vector network analyzer. Previous theories did not consider effects of optical coherence 

on such measurements, and this work describes 

how coherence effects can be avoided to give more 

accurate measurements.

Established sampling oscilloscope calibration 

capability, traceable to the NIST EOS system, with 

full covariance-based uncertainty analysis. This 

capability is now available as a Special Test for 

both internal and external customers. 

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Electro-optic sampling is capable of determining the vector frequency response of a photodiode; that is, it can 

determine both the magnitude and phase response of the photodiode.
Optoelectronics Division 13

Implemented new 1.5 μm measurement system 

for low-level radiometers, leading to an improvement in measurement stability by a factor of two.

Consolidated high speed measurement programs in Boulder from the Quantum Electrical 

Metrology Division in Gaithersburg. Transferred 

impulse spectral amplitude measurement service to 

Boulder and added phase measurement capability. 

Transferred pulse parameter measurement service 

and pulse time delay service.

MEASUREMENT SERVICES

The Optoelectronics Division provides measurement services relating to the temporal properties of 

optical sources and detectors used with optoelectronic systems, including optical receiver frequency 

response (scalar or vector), impulse response, and 

low-level pulse power and energy. Measurement 

services for electrical oscilloscope impulse response, waveform parameters of pulse generators, 

and spectrum of pulse generators have also recently 

been added. For more information see Appendix D, 

or contact Paul Hale at (303) 497-5367. 

STANDARDS COMMITTEE

PARTICIPATION

International Electrotechnical Commission: Paul 

Hale is a member of technical committee TC86, 

working group 4, which deals with Fiber Optic 

Test Equipment Calibration.

International Telecommunication Union: Paul Hale 

is a technical correspondent for ITU-T Study Group 

4 working on recommendations for instrumentation 

measuring jitter and wander in synchronous digital 

hierarchy (SDH) equipment.

RECENT PUBLICATIONS

P. D. Hale, C. M. Wang, D. F. Williams, K. A. Remley, and J. 

D. Wepman, “Compensation of random and systematic timing 

errors in sampling oscilloscopes,” accepted for publication in 

IEEE Trans. Instrum. Meas., Vol. 55 (2006).

T. S. Clement, P. D. Hale, D. F. Williams, C. M. Wang, A. Dienstfrey, and D. A. Keenan, “Calibration of sampling oscilloscopes 

with high-speed photodiodes,” IEEE Trans. Microwave Theory 

Tech., Vol. 54, pp. 3173–3181 (2006).

A. Dienstfrey, P. D. Hale, D. A. Keenan, T. S. Clement, and D. 

F. Williams, “Minimum-phase calibration of sampling oscilloscopes,” IEEE Trans. Microwave Theory Tech., Vol. 54, pp. 

3197–3208 (2006).

D. F. Williams, H. Khenissi, F. Ndagijimana, K. A. Remly, J. 

P. Dunsmore, P. D. Hale, J. C. M. Wang, and T. S. Clement, 

“Sampling-oscilloscope measurement of a microwave mixer 

with single-digit phase accuracy,” IEEE Trans. Microwave 

Theory Tech., Vol. 54, pp. 1210–1217 (2006).

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D. F. Williams, A. Lewandowski, T. S. Clement, J. C. M. Wang, 

P. D. Hale, J. M. Morgan, D. A. Keenan, and A. Dienstfrey, 

“Covariance-based uncertainty analysis of the NIST electrooptic sampling system,” IEEE Trans. Microwave Theory Tech., 

Vol. 54, pp. 481–491 (2006).

D. F. Williams, P. D. Hale, T. S. Clement, and J. M. Morgan, 

“Calibrated 200 GHz waveform measurement,” IEEE Trans. 

Microwave Theory Tech., Vol. 53, pp. 1384–1389 (2005).

D. Williams, P. Hale, T. Clement, and C. M. Wang, “Uncertainty 

of the NIST electrooptic sampling system,” NIST Technical 

Note 1535 (2004).

R. W. Leonhardt, “Calibration service for low-level pulsed-laser 

radiometers at 1.06 μm: pulse energy and peak power,” NIST 

Special Publication 250-64 (2004).

P. Bryant, J. Grigor, P. Harris, B. Rich, A. Irwin, S. McHugh, D. 

W. King, and R. W. Leonhardt, “Advanced test and calibration 

systems for integrated multi-sensor platforms with IR, visible, 

and laser range fi nder/designator capabilities,” Proc., SPIE, 

Vol. 5076, The International Society for Optical Engineering, 

Infrared Imaging Systems: Design, Analysis Modeling and 

Testing XIV (2003).

K. J. Coakley, C. M. Wang, P. D. Hale, and T. S. Clement, 

“Adaptive characterization of jitter noise in sampled high-speed 

signals,” IEEE Trans. Instrum. Meas., Vol. 52, pp. 1537–1547 

(2003).

P. D. Hale and D. F. Williams, “Calibrated measurement of 

optoelectronic frequency response,” IEEE Trans. Microwave 

Theory Tech., Vol. 51, pp. 1411–1429 (2003).

T. S. Clement, D. F. Williams, P. D. Hale, and J. M. Morgan, 

“Calibrating photoreceiver response to 110 GHz,” IEEE Lasers and Electro-Optics Society Annual Meeting Digest, pp. 

877–878 (2002).

T. S. Clement, P. D. Hale, P. A. Williams, “Tutorial: fi ber and 

component metrology for high-speed communication,” Proc., 

Optical Fiber Communication Conf., March 17–22, Anaheim, 

CA, WZ1 (2002).

C. W. Wang, P. D. Hale, K. J. Coakley, and T. S. Clement, “Uncertainty of oscilloscope timebase distortion estimate,” IEEE 

Trans. Instrum. Meas., Vol 51, pp. 53–58 (2002).
14 Electronics and Electrical Engineering Laboratory

INTERFEROMETRY AND POLARIMETRY

Technical Contact:

Paul Williams

Staffi ng (FY06):

3 professionals

0.5 technician

1 associate

GOALS

To provide supporting metrology for interferometric and polarimetric applications including 

telecommunications, sensing, and medical imaging 

by providing measurements, calibrations, standards, and expertise, drawing on a strong technical 

background in interferometry and polarimetric 

techniques. 

CUSTOMER NEEDS

BIOMEDICAL IMAGING

In the fi eld of medical imaging, Optical Coherence 

Tomography (OCT) is a technique for minimally 

invasive noncontact three-dimensional imaging 

of tissue with micrometer-scale resolution. Two 

innovations are key to enabling broad application 

in medical diagnostics: increased measurement 

speed (image quality, screening costs, and patient 

comfort depend on rapid scans) and better measurement validation (enables technology-invariance 

and instrument interoperability). These innovations 

will change OCT, a young biomedical imaging 

technique, into a widely applicable, quantitative 

measurement tool for absolute assessment of tissue health.

Measurement speed is limited by a lack of rapidly 

tuning low-noise lasers and low-noise spectrally 

shaped broad-band light sources, high-sensitivity 

detectors, cost-effective near-IR detector arrays, 

and by measurement noise in general. Measurement validation is limited by the current OCT 

accuracy assessments, availability of comparable 

techniques, well characterized and stable phantoms, and an incomplete data bank of optical 

properties of tissue (refractive index, scattering, 

and absorption parameters).

OPTICAL FIBER TELECOMMUNICATIONS

In optical fi ber communication systems, dispersion broadens the optical pulses, making it diffi cult 

to distinguish adjacent data bits, causing communication errors. Dispersion in optical fi ber arises from 

the variation of the light’s propagation velocity as a 

function of wavelength or polarization state. Mitigation of system chromatic dispersion (through 

dispersion-tailored fi bers, dispersion mapping, 

and dispersion compensating fi bers) requires accurate measurement of the wavelength dependence 

of chromatic dispersion, and the ability of users 

to verify this accuracy. Wavelength-dependent 

relative group delay (RGD) in optical components 

(such as narrow-band fi lters for 40 Gbit/s data 

rates) is more challenging to characterize and can 

have requirements for subpicosecond resolution in 

bandwidths on the order of tens of picometers. To 

simultaneously optimize these opposing resolutions requires high measurement signal-to-noise 

ratio and drift reduction.

In polarization-mode dispersion (PMD), where 

propagation velocity depends on the polarization 

state of the light, communication systems can 

require PMD measurements to have temporal 

resolutions of tens of femtoseconds with spectral 

resolutions of tens of picometers. Again, this 

mutual resolution requirement requires low-noise 

measurements (high spectral effi ciency).

OPTICAL FIBER SENSORS

Over the past 10 years Fiber Bragg Gratings 

(FBG) have come to play an important role in 

passive strain and stress detection. In the simplest 

form they are used as optical strain gauges. The 

complete state of stress in a host material can be 

measured by embedding several of these strain 

gauge sensors in the material in orthogonal directions. However, this level of complexity can be 

diffi cult to implement, and the presence of a large 

number of sensors may weaken the material. Novel, 

low-cost measurement approaches are therefore 

needed to allow a full vector characterization of 

stress with spatial resolutions less than the dimensions of a single FBG.

TECHNICAL STRATEGY

We address the above metrology needs through the 

development of unique, high-resolution measurement techniques with rigorous uncertainty analysis, 

metrology transfer via calibrations, development 

and distribution of well-characterized artifacts, 

measurement comparisons, and Special Tests of 

customer artifacts.

OPTICAL COHERENCE TOMOGRAPHY

(OCT) 

Phase-Dispersion Light Scattering: We currently 

have the capability to accurately measure the phase 

of scattered light as a function of wavelength using 

swept-source OCT measurement systems operating 

at both 1320 and 1575 nm. We have demonstrated 

the ability to extract from this phase-dispersion 

spectra the size of multiple spherical scatters in the 
Optoelectronics Division 15

specimen. This is done with application to determining the size of cell nuclei, which is important as 

an early indicator of cancer. Healthy nuclei are typically 4-7 micrometers in diameter, while cancerous 

nuclei are up to 20 micrometers in diameter.

In collaboration with NIST Physics Laboratory and 

the Information Technology Laboratory researchers, we have used Mie scattering theory to predict 

the phase spectrum of light scattered from spherical 

particles, and we have demonstrated theoretically 

a nonequivalence between this phase scattering 

spectrum and the more conventional intensity 

scattering spectrum for the case of a single spherical scatterer. This indicates that both intensity and 

phase are required for a full characterization of the 

tissue constituents via spectral light scattering OCT. 

To this end, we have developed a phase measurement capability and demonstrated it as a technique 

to measure scatterer size in tissue phantoms composed of small (5-30 micrometers) polystyrene 

spheres in different confi gurations: embedded in 

a glycerin/water solution, monolayers of spheres 

on microscope slides, and a size domain sample 

with monolayers of two distinct sizes of spheres 

adjacent to each other. In addition, raster-scan 

measurements have been performed on epithelial 

cheek cells, cancerous liver tissue, and rat vascular 

endothelial cells.

Sphere diameter as a function of position across 

the boundary between regions of 15 μm and 26 μm 

spheres measured using phase-dispersion OCT technique.

PLAN: We will evaluate our phase-dispersion contrast 

measurements of cell and tissue samples in order to 

verify the measurements, validate the scatterer size, 

demonstrate contrast, and estimate the measurement 

uncertainty.

Polarization-Sensitive OCT (PS-OCT) allows 

the measurement of differential changes in tissue 

refractive index due to the anisotropic nature of 

most tissue. PS-OCT increases contrast in many 

tissues, providing a sensitive measure of tissue 

health including early identifi cation of glaucoma, 

characterization of the arterial plaques that lead to 

heart attacks, and assessment of burn depth. We 

have assembled a time-domain PS-OCT system 

to measure tissue birefringence.

PLAN: We are developing adjustable-birefringence 

tissue phantoms that we will characterize and distribute 

among researchers and instrument makers to assess 

the current ability of the biomedical imaging industry to 

accurately measure tissue birefringence. 

CHROMATIC DISPERSION & RELATIVE

GROUP DELAY

With our 2 GHz modulation phase shift (MPS) system we offer Special Test measurements of chromatic dispersion and zero-dispersion wavelength 

on customer-supplied fi bers over the wavelength 

range from 1442 nm to 1620 nm. Using a 200 MHz 

MPS system, we are able to measure component 

group delay features with 0.072 ps resolution and 

a single spectral sweep accuracy of 0.46 ps with 

a spectral resolution of 3.2 pm. This capability is 

available to customers as a Special Test over the 

wavelength range of 1510 nm to 1620 nm.

In 2004, we participated with other national 

laboratories in a EUROMET comparison of chromatic dispersion, zero-dispersion wavelength, and 

dispersion slope. The full report is available from 

the BIPM website at http://www.bipm.org/utils/

common/pdf/final_reports/PR/S1/EUROMET.

PR-S1.pdf 

POLARIZATION-MODE DISPERSION (PMD)

We provide two artifact standards characterized for 

their PMD (wavelength-averaged differential group 

delay, DGD), one with polarization-mode coupling 

to simulate measurements of optical fi ber (SRM 

2518), and the other, a non-mode-coupled device 

to simulate measurements of optical components 

(SRM 2538). We also offer PMD measurements 

on customer-supplied artifacts. Our narrow-bandwidth PMD metrology yields DGD measurements 

with 9 fs uncertainty in a 40 pm bandwidth. 

OPTICAL FIBER BRAGG GRATING INDEX

PROFILE

We currently have the capability to measure the 

magnitude of transverse stresses on fi ber Bragg 

gratings (FBG) with a spatial resolution of 12 μm 
16 Electronics and Electrical Engineering Laboratory

and a minimum detectable stress of 1.4 N•mm-2. 

This method uses a four-state polarization analysis combined with a “layer-peeling” algorithm to 

eliminate the need for polarization-maintaining 

fi ber in the sensor. Our measurement systems are 

based on low-coherence interferometry and have 

been implemented in both the time and frequency 

domains.

COMPONENT SPECTRAL TRANSMISSION/

REFLECTION

We have the capability to characterize spectral 

reflection/transmission profiles in fiber Bragg 

gratings with sub-picometer accuracy. This is 

supported by both frequency-domain and lowcoherence interferometry approaches. Spectral 

characterization systems are currently available 

for spectral refl ectance profi ling of a variety of 

optical fi lters.

OPTICAL RETARDANCE

We have retardance measurement capability in the 

near infrared and a high-accuracy (~0.1°) quarterwave retarder artifact for customer measurement 

verifi cation.

ACCOMPLISHMENTS

Multiple Diverse OCT Measurement Systems 

Developed. We have assembled four OCT measurement systems: two swept-laser frequency-domain 

systems in the 1300 and 1550 nm regions for measuring dispersion, a spectral-domain system with a 

1260-1560 nm broadband source for high spatial 

resolution, and a time-domain polarization-sensitive OCT system at 1320 nm for measurement of 

tissue anisotropy.

Measured the Phase Dispersion Spectra 

of Microscatterers. We have demonstrated the 

ability to measure the phase-dispersion spectra of 

scatterers as small as 5 micrometers. For these 

measurements, we developed tissue phantoms by 

embedding small (5-15 micrometers) polystyrene 

spheres in a glycerin/water solution. We demonstrated that the periodicity of the phase dispersion 

spectra is directly correlated with the size of the 

scatterer, and we demonstrated good agreement 

with theoretic predictions of the phase dispersion 

spectra. 

Dispersion Contrast OCT Technique Demonstrated. We have demonstrated the ability to use 

phase-dispersion spectra as the contrast mechanism 

in a surface scan of a tissue phantom composed of 

two different sizes of polystyrene spheres (15 and 

26 micrometer diameters). The result is a false-

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color image of the tissue phantom where the local 

sphere diameter is indicated by color change. In 

this phantom, the spheres emulate cell nuclei. Our 

measurements show agreement with theoretical 

predictions of dispersion based on phase-sensitive 

Mie scattering theory developed in collaboration 

with the NIST Physics Laboratory and the Information Technology Laboratory. This technique is important for tissue characterization because nuclear 

size is one indicator of precancerous conditions.

Comparison of measured and predicted phase dispersion spectra of phantoms constructed from polystyrene 

spheres embedded in a glycerin/water solution.

Theoretical Nonequivalence of the Intensity 

and Phase Scattering Signatures Established. We 

have succeeded in demonstrating the theoretical 

nonequivalence of the spectral intensity and phase 

scattering signatures from a single spherical particle. Other groups have been using intensity based 

scattering for sizing of cell nuclei. However, this 

theoretical result demonstrates the need for both 

phase and intensity data for full characterization 

of cell nuclei.

Phase-Dispersion Imaging Applied to Tissue 

and Cell Cultures. We have developed the ability 

to produce raster-scanned images of cell cultures 

and tissue samples with scattering dispersion as the 

contrast mechanism. Raster-scan measurements 

have been performed on epithelial cheek cells, 

cancerous liver tissue, and rat vascular endothelial 

cells, and we obtained reasonable sizes for the 

nuclei from those measurements.

Model Developed to Identify Sources of Noise 

in Polarization-Sensitive OCT. In a collaboration 

between NIST, the National Physical Laboratory 

(UK), and the University of Texas, a model has 

been developed to describe the sources of noise 

encountered in polarization-sensitive Optical Co-

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Optoelectronics Division 17

herence Tomography (PS-OCT). This model will 

aid the development of noise reduction techniques 

leading to faster and more sensitive measurements. 

PS-OCT increases contrast in many tissues, providing a sensitive measure of tissue health. Noise 

affects PS-OCT results by reducing image quality 

and increasing measurement time. Three distinct 

noise mechanisms were identifi ed (intensity noise, 

polarization speckle, and polarization-dependent 

scattering).

High Spatial Resolution Measurement of 

Transverse Stress Achieved with FBG Sensor. We 

have demonstrated a new method for measurements 

at high spatial resolution of the two components of 

transverse stress in a distributed fi ber Bragg grating 

(FBG) strain sensor. The relative index of refraction 

as a function of position in the FBG was determined 

by either time-domain or frequency-domain interrogation systems via a layer-peeling algorithm. With 

this method we are able to measure changes in the 

refractive index with resolution better than 5x10-6

and a spatial resolution of 12 μm. To determine 

transverse stress, we repeated the measurement for 

four different polarization states using a four-state 

analysis to determine the birefringence as a function of position in the grating. This measurement 

offers the advantage that it does not require the use 

of polarization maintaining fi ber, which is expensive and more diffi cult to splice. Measurements 

of the externally induced birefringence agree well 

with values predicted by the stress-optic properties 

and the geometry of the fi ber.

Bilateral Comparison of Polarization-Mode 

Dispersion Completed: NIST and the Korean Research Institute of Standards and Science (KRISS) 

have performed a measurement comparison on 

mode-coupled artifacts constructed of spliced 

polarization maintaining fi ber in a temperature 

controlled environment.

Body Armor Testing Technique Developed. 

Our investigation into a variety of sensing techniques to assess the shape deformation and force 

distribution of bullet-resistant vests has identifi ed 

fi ber-optic bend loss as a promising technique. 

We developed the technique further by estimating 

measurement sensitivity and repeatability.

USMS Workshops Conducted to Assess Measurement Needs. In support of the United States 

Measurement System (USMS) assessment, workshops were held to collect industry input on the 

measurements needed for optical fi ber broadband 

communications, and biophotonic diagnostics.

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STANDARDS COMMITTEE PARTICIPATION

IEC TC86/WG4 & IEC SC86C/WG3 Fiber Optics 

Calibration & Optical Amplifi ers

USTAG SC86A IEC U.S. Technical Advisory 

Group – Optical Fibers and Cables

USTAG SC86C IEC U.S. Technical Advisory 

Group – Systems and Active Devices

USTAG TC86 IEC U.S. Technical Advisory Group 

– Fiber Optics

TIA FO-4 Committee on Fiber Optics, subcommittee Vice-Chair, working group Chair

STANDARD REFERENCE MATERIALS

(SRM) (SEE APPENDIX E)

http://www.boulder.nist.gov/div815/SRMS/SRMS.htm

SRM 2513, Mode-Field Diameter of Single-Mode Fiber.

SRM 2518/2538 Polarization-Mode Dispersion (Mode-Coupled 

/ Non-Mode-Coupled).

SRM 2520, Optical Fiber Diameter

MEASUREMENT SERVICES

(NIST SPECIAL TESTS)

Optical Fiber Chromatic Dispersion, Zero-Dispersion Wavelength, and Dispersion Slope

Optical Linear Retardance Standard (high-accuracy 

quarter-wave retarder)

Polarization-Mode Dispersion

RECENT PUBLICATIONS

http://www.boulder.nist.gov/div815/81503_pubs.htm

S. D. Dyer, T. Dennis, L. Street, S. M. Etzel, T. A. Germer, 

and A. K. Dienstfrey, “Spectroscopic phase dispersion optical 

coherence tomography measurements of scattering phantoms,” 

Optics Express, Vol. 14, No. 18, pp. 8138–8153 (2006).

R. A. Hoffman, M. Brownstein, T. E. Milner, R. Levenson, M. 

L. Dowell, P.A. Williams, G. White, A. Gaigalas, J. Hwang, 

“Biophotonic tools in cell and tissue diagnostics,” submitted 

to NIST Journal of Research (2006). 

R. J. Espejo, M. Svalgaard, and S. D. Dyer, “Characterizing 

fi ber Bragg grating index profi les to improve the writing process,” IEEE Photonics Technology Letters, Vol. 18, 2242–2244 

(2006).

R. J. Espejo and S. D. Dyer, “High-spatial resolution measurements of transverse stress using four-polarization-state frequency domain interferometry,” 18th International Conference on 

Optical Fiber Sensors, Oct 23–27, Cancun, Mexico (2006).

P. A. Williams and T. J. Drapela, “Technical Digest, SOFM 

2006: A NIST symposium for photonic and fi ber measurements,” Boulder, CO. Special Publication (NIST SP 1055) 

(2006).
18 Electronics and Electrical Engineering Laboratory

R. J. Espejo and S. D. Dyer, “High spatial resolution measurements of transverse stress in a fi ber Bragg grating using 

four-state analysis low-coherence interferometry and layerpeeling,” Smart Structures and Materials 2006: Smart Sensor 

Monitoring Systems and Applications, SPIE Annual Intl Symp. 

on Smart Structures and Materials, Feb 26–Mar 02, San Diego, 

CA (2006).

S. D. Dyer, T. Dennis, P. A. Williams, L. Street, S. M. Etzel, 

R. J. Espejo, T. A. Germer, and T. E. Milner, “High sensitivity measurements of the scattering dispersion of phantoms 

using spectral domain optical coherence tomography,” SPIE 

Coherence Domain Optical Methods and Optical Coherence 

Tomography in Biomedicine X, Vol. 6079, paper 43, Jan 21–26, 

San Jose, CA (2006).

P. A. Williams, N. J. Kemp, D. Ives, J. Park, J. C. Dwelle, H. 

G. Rylander, and T. E. Milner, “Noise model for polarizationsensitive optical coherence tomography,” SPIE Coherence 

Domain Optical Methods and Optical Coherence Tomography 

in Biomedicine X, 2006, Vol. 6079, paper 56, Jan 21–26, San 

Jose, CA (2006).

T. J. Drapela, “Measurement ‘round robins’ support fi ber standards development,” Lightwave, Vol. 23, No. 1, p. 19 (2006).

T. Dennis and P. A. Williams, “Achieving high absolute accuracy for group-delay measurements using the modulation 

phase-shift technique,” J. Lightwave Technol., Vol. 23, No. 11, 

pp. 3748–3754 (2005).

S. D. Dyer, P. A. Williams, R. J. Espejo, J. Kofl er, and S. M. Etzel, “Fundamental limits in fi ber Bragg grating peak wavelength 

measurements,” Proc. of SPIE, 17th International Conference 

on Optical Fiber Sensors, May 23–27, Bruges, Belgium, Vol. 

5855, pp. 88–93 (2005).

T. Dennis, P. A. Williams, “High-accuracy optical group delay 

measurements and modulator chirp characterization,” International Topical Meeting on Microwave Photonics, Oct 04-06, 

Ogunquit, ME, pp. 32–35 (2005).

T. Dennis and P. A. Williams, “Chromatic dispersion measurement error caused by source amplifi ed spontaneous emission,” 

IEEE Photon. Tech. Lett., Vol. 16, No. 11, pp. 2532–2534 

(2004).

P. A. Williams, “PMD measurement techniques and how to 

avoid the pitfalls,” Journal of Optical and Fiber Communications Reports, Vol. 1, No. 1, Springer, pp. 84–105 (2004).

R. J. Espejo, S. D. Dyer, and M. Svalgaard, “Analysis of a fi ber 

Bragg grating writing process using low-coherence interferometry and layer-peeling,” Tech. Dig., Symp. on Optical Fiber 

Meas., Sept. 28–30, Boulder, CO, pp. 195–198 (2004).

P. A. Williams and G. W. Day, “Technical digest, symposium on 

optical fi ber measurements,” Boulder, CO, Special Publication 

(NIST SP 1024) (2004).
Optoelectronics Division 19

SPECTRAL AND NONLINEAR PROPERTIES

Technical Contact:

Nate Newbury

Staffi ng (FY06): 

2 professional

1 associate

GOALS

Develop techniques for the generation, amplifi cation, dissemination, and characterization of stable, 

low-noise optical sources for fi ber optic-based 

systems. (Current work focuses on the development and applications of fi ber optic frequency 

combs). Support current wavelength-calibration 

transfer standards in the near infrared region to 

help industry calibrate equipment, and explore 

new techniques for future higher-precision transfer 

standards. 

CUSTOMER NEEDS 

In the past, this project concentrated on the measurement needs of the optical fi ber communications 

industry. More recently our focus has expanded 

to address the broader needs for metrology and 

stable optical sources in the near-infrared region 

that arise in a variety of applications, including 

coherent communications, LIDAR, and optical 

fi ber sensors. 

By using many wavelength channels simultaneously, wavelength division multiplexing (WDM) 

has been very successfully applied to increasing 

the transmission bandwidth of optical-fi ber communication systems. Most WDM systems employ 

50 or 100 GHz channel spacing (0.4 or 0.8 nm, 

respectively) in the 1540 to 1560 nm region. For 

effective system operation, the source wavelength 

and the wavelength dependence of any components 

must be well characterized and controlled. In the 

past, this project has developed Standard Reference 

Materials (SRMs) that provide wavelength standards in this region for calibration of measurement 

equipment. To support requirements of even higher 

bandwidths, future systems will either expand into 

other wavelength regions or increase transmission 

effi ciency within the current spectral region and 

will likely require the development of new, more 

accurate transfer standards. 

Partly because of the dramatic increase in the available sources and components at telecommunication wavelengths, this area of the spectrum fi nds 

increasing applications in sensing. For example, 

optical-fi ber sensors can detect small changes in 

stress, or temperature, based on the wavelength 

shift of fi ber Bragg grating refl ection peaks. The 

sensitivity is determined by the wavelength accuracy of the interrogation unit; some systems need 

wavelength calibration to better than 1 pm. As 

another example, coherent LIDAR systems can 

be used to probe the atmosphere and for military 

sensing applications. Operation near 1.5 μm is 

attractive because it is eye-safe compared to the 

visible region, there is an abundance of available 

technology, and there are amplifi ers available of 

increasingly higher power. The ability to generate and transmit highly frequency-stable (i.e., low 

phase noise) optical sources translates directly 

into increased sensitivity for coherent LIDAR. 

Coherent free-space communications shares the 

same essential features as coherent LIDAR and 

will similarly benefi t from well characterized, 

frequency-stable optical sources. Therefore, all 

of these applications share the same basic metrological needs of measuring an optical frequency. 

The current gold standard for measuring optical 

frequencies is the optical frequency comb. 

TECHNICAL STRATEGY

Supporting optical fi ber and component metrology needs requires development and evaluation 

of new measurement techniques, basic technology, 

dissemination of this knowledge, and, when appropriate, development of SRMs or other calibration 

aids to help industry calibrate instrumentation. 

The project currently focuses on three areas: 1) 

developing very low-noise fi ber- frequency combs 

covering the near infrared, 2) expanding the applications of these frequency combs to different areas, 

and 3) supporting current wavelength calibration 

standards in the near infrared region.

FIBER FREQUENCY COMB DEVELOPMENT

Frequency combs can provide a set of evenly 

spaced, exactly positioned lines across the near 

infrared region of the optical spectrum. These 

combs are ideally suited to supporting very highly 

accurate metrology in the near-infrared since they 

can be used as a precise spectral ruler. In addition to their application to wavelength metrology, 

frequency combs are potentially enabling sources 

for a number of other applications discussed 

below. Much of the original work on frequency 

combs used Ti:Sapphire lasers and took place in 

the Physics Laboratory at NIST. These Ti:Sapphire frequency combs cover mainly the visible 

region, and do not reach far enough into the near 

infrared to cover the “transparent” window of optical fi ber (1.1 to 1.7 μm). In order to reach this 

spectral region, we have been developing optical 

fi ber laser-based frequency combs. To generate an 

optical frequency comb in the near infrared, pulses 
20 Electronics and Electrical Engineering Laboratory

from a mode-locked fi ber laser are launched into 

highly nonlinear optical fi ber, which broadens 

the laser spectrum to a supercontinuum with a 

width of greater than 1000 nm. Since the laser is 

pulsed, this broad supercontinuum will actually 

be composed of discrete frequency lines – a frequency comb – spaced by the laser repetition rate. 

This optical frequency comb can be stabilized to 

provide discrete frequency or wavelength markers throughout the 1100 to 2000 nm region. Any 

unknown optical frequency can then be measured 

by simply comparing its frequency to that of the 

nearest tooth of the stabilized frequency comb. Fiber laser-based frequency combs can be much more 

compact, robust, power-effi cient, and lighter than 

bulk optic solid-state laser-based frequency combs, 

and commercial fi ber-laser frequency combs are 

now available from several companies. Our goal 

at NIST is to understand the current limitations of 

fi ber frequency combs and to increase their performance, as measured by either the stability or the 

phase noise of the individual comb lines. Minimization of noise for fi ber frequency combs involves 

research in a wide range of areas, including design 

and theory of femtosecond fi ber lasers, spectral 

broadening in highly nonlinear optical fi ber, linear 

and nonlinear fi ber optic effects that occur during 

the transmission of cw or pulsed optical signals, 

and feedback control systems.

The linewidth of a low phase-noise fi ber frequency 

comb. The individual traces represent the heterodyne 

beat between two low-noise fi ber frequency combs 

(one from NIST and one from a collaborator) at different points across the spectrum. The inset shows the 

rf heterodyne beat on a larger scale. The pedestal in 

that signal represents uncorrected phase noise that 

amounts to only one radian of optical phase noise.

PLAN:

Develop fi ber frequency comb into tool for high 

accuracy (i.e., hertz-level) optical frequency 

measurement. 

Investigate phase and amplitude noise on fi ber-laser 

based frequency combs

Explore fi ber-induced limitations to the dissemination of 

highly stable cw or pulsed laser light over optical fi ber 

networks.

APPLICATIONS DEVELOPMENT

As discussed above, fi ber frequency combs are 

ideally suited for metrology of optical sources; 

however, they are also well suited for any other 

applications that benefi t from a low phase-noise, 

wideband optical source. We are interested in demonstrating the use of fi ber frequency combs in both 

metrological and nonmetrological applications.

Two interesting metrological applications are 

laser source characterization and fi ber-optic dissemination of fundamental wavelength, time, and 

frequency standards. Currently, the phase noise 

of commercial lasers is specified by a single, 

poorly defi ned linewidth parameter. As lasers are 

employed in applications requiring signifi cantly 

lower levels of phase noise, this parameter will be 

completely inadequate, and much better-defi ned 

specifi cations will be needed. Specifi cally, lasers 

are simply optical oscillators and, as such, should 

have phase noise specifi cations mirroring those of 

commercial rf synthesizers. Such information on 

laser performance is easily provided by comparison 

with a single tooth from a low-noise fi ber frequency 

comb. A second promising metrological application for combs is the dissemination of wavelength 

standards, frequency standards, and time over large 

distances by use of fi ber optic networks. The dissemination of these standards is complicated by 

both linear and nonlinear effects that will degrade 

the phase quality of the signal. Nevertheless, several groups have demonstrated precise frequency 

transfer over local area networks. We are interested 

in conducting experiments to establish the limits of 

fi ber-optic dissemination of wavelength, frequency, 

and time over very large fi ber networks. 

A number of applications can benefi t from the 

high stability, low phase noise, wide bandwidth or 

very low timing jitter provided by fi ber frequency 

combs. These applications range from straightforward spectroscopy to arbitrary optical waveform 

generation, optical coherence tomography, coherent LIDAR for remote sensing, and precise ranging 

for semiconductor manufacturing. For example, 

the wide bandwidth of the comb provides very high 

range resolution, which can be exploited in any 

ranging system, whether it be for optical coherent 

tomography, a ranging coherent LIDAR system, 

or a precision stepper system in a manufacturing 
Optoelectronics Division 21

environment. We have conducted an initial laboratory experiment demonstrating the advantages of a 

fi ber frequency comb source for a ranging LIDAR 

system. This same system can also provide very 

precise vibrometry signatures. We will continue 

to explore the utility of fiber frequency comb 

sources for these applications through laboratory 

demonstrations. 

Example range image collected with a fi ber frequency 

comb source and frequency-domain signal processing. 

The image is of a rotating disk that had a 100 micrometer wobble. The resolution is about 50 micrometers 

and is limited only by the 25-nm bandwidth of the 

erbium-doped fi ber amplifi er used to transmit the fi ber 

frequency comb pulses. 

PLAN: 

Demonstrate the applicability of fi ber frequency comb 

sources to remote sensing, including precise rangeDoppler measurements.

Provide the capability of measuring the stability and 

phase noise of optical sources in the near-infrared.

Long term: Develop and implement plan to disseminate 

wavelength/frequency standards via optical frequency 

combs and optical fi ber. 

WAVELENGTH CALIBRATION STANDARDS

Fundamental wavelength references based on 

atomic and molecular absorption or emission lines 

provide high accuracy, but they are not available 

in all wavelength regions. The project currently 

produces four wavelength reference SRMs based 

on fundamental molecular absorption lines: SRM 

2514 (carbon monoxide 12C16O), SRM 2515 (carbon monoxide 13C16O), SRM 2517a (acetylene, 

high resolution), and SRM 2519a (hydrogen cyanide). Together these SRMs can be used to calibrate the wavelength scale of instruments between 

1510 nm and 1630 nm. WDM can expand into 

other wavelength regions, such as the 1300–1500 

nm region. For the near term, we will continue to 

support these SRMs as well as monitor industry to 

anticipate future needs.

ACCOMPLISHMENTS

Sub-Hertz Linewidth Fiber Laser Frequency 

Comb Demonstrated — We demonstrated a subhertz residual linewidth fi ber laser frequency comb 

in collaboration with an outside company. Each 

individual comb line had a measurement-limited 

linewidth of less than 100 mHz and a residual 

phase noise of less than 1 radian. The extrapolated 

timing jitter was less than 1 femtosecond. This 

demonstration indicates that the fi ber-laser based 

comb can have performance approaching that of 

the Ti:Sapphire based systems.

High Stability Achieved for Fiber Laser Frequency Comb Offset Frequency — We succeeded 

in stabilizing the carrier-envelope offset frequency 

from a fi ber laser frequency comb very tightly. In 

the laser output pulses, the relative jitter between 

the optical carrier wave and the pulse envelope 

is below a few radians. This high stability should 

benefi t both high precision frequency metrology 

and future time-domain experiments with fi ber 

laser frequency combs.

Theory for the Response of Fiber Laser Developed and Verifi ed — We developed a theory for 

the response of fi ber-laser based optical frequency 

combs to changes in the pump power, cavity length, 

and other experimentally-accessible parameters. 

The theory predicts the comb response in terms 

of transfer functions. Interestingly, it is a quite 

a complicated system and there are at least fi ve 

different mechanisms that can play important 

roles in the laser response. We have also verifi ed 

the theory by conducting experimental measurements on frequency combs and showed that the 

response is consistent with the theory. In addition, 

the theory predicts that other control parameters 

could be used to improve the stability of the comb 

and provide better ultimate performance of the 

frequency comb.

Frequency-Resolved Coherent LIDAR Technique Developed — We have demonstrated a 

six-channel frequency-resolved coherent LIDAR 

(FReCL) using an optical frequency comb. It provides one-sixth of the noise of conventional LIDAR 

for speckle-limited signals, drastically reduces the 

required accuracy and steps of the variable delay 

line, and permits phase compensation even with 

signifi cant phase distortions in the signal path. 

The system can be implemented with many more 

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22 Electronics and Electrical Engineering Laboratory

channels and a corresponding improvement in 

signal-to-noise ratio. 

High Accuracy Wavelength Calibration SRM 

for the 1530-1565 nm Region Available — A new 

wavelength reference for the 1530 to 1565 nm 

region is now available as Standard Reference 

Material 2519a. The SRM is an upgrade of SRM 

2519 and is more than an order of magnitude more 

accurate than its predecessor; a selection of the 

absorption lines of hydrogen cyanide are certifi ed 

with an uncertainty of 0.04 pm (about 5 MHz). 

Thus, SRM 2519a enables wavelength calibration of test and measurement equipment at much 

higher-accuracy.

STANDARD REFERENCE MATERIALS

(SRM) (SEE APPENDIX E) 

See http://www.boulder.nist.gov/div815/SRMS/SRMS.htm 

for descriptions

SRM 2513, Mode Field Diameter Standard for Single-Mode 

Fiber

SRM 2514, Wavelength Calibration Reference for 1560–1595 

nm – Carbon Monoxide 12C16O

SRM 2515, Wavelength Calibration Reference for 1595–1630 

nm – Carbon Monoxide 13C16O

SRM 2517a, High Resolution Wavelength Calibration Reference for 1510–1540 nm – Acetylene 12C2

H2

SRM 2519a, High Resolution Wavelength Calibration Reference for 1530–1565 nm – Hydrogen Cyanide H13C14N

SRM 2520, Optical Fiber Diameter Standard

RECENT PUBLICATIONS

See http://www.boulder.nist.gov/div815/81503_pubs.htm for 

publications.

W. C. Swann, J. J. McFerran, I. Coddington, N. R. Newbury, I. 

Hartl, M. E. Fermann, P. S. Westbrook, J. Nicholson, K. Feder, 

C. Langrock, M. Fejer, “Fiber-laser frequency combs with subHz residual linewidths,” Opt. Lett., in press.

J. J. McFerran, W. C. Swann, B. R. Washburn, N. R. Newbury, 

“Pump-induced frequency noise in fi ber laser frequency combs 

and fceo phase excursions suppressed to 1 radian,” submitted 

to Appl. Phys. B., in press.

J. J. McFerran, W. C. Swann, B. R. Washburn, N. R. Newbury, 

“Characterization and elimination of the pump-induced frequency jitter of fi ber-laser frequency combs,” Opt. Lett., Vol. 

31, No. 13, pp. 1997–1999, (2006).

N. R. Newbury, W. C. Swann, I. Coddington, J. J. McFerran, 

“Fiber frequency combs: development and applications,” Tech. 

Dig., Symp. on Optical Fiber Meas., Sep 19–20, Boulder, CO, 

NIST Special Publication 1055, pp. 45–50 (2006).

W. C. Swann, N. R. Newbury, “Frequency-resolved coherent 

LIDAR using a femtosecond fi ber laser,” Opt. Lett., Vol. 31, 

No. 6, pp. 826–828 (2006).

■

B. Washburn, W. C. Swann, N. R. Newbury, “Response dynamics of the frequency comb output from a femtosecond 

fi ber laser,” Optics Express, Vol. 13, No. 26, pp. 10622–10633 

(2005).

N. R. Newbury, B. Washburn, “Theory of the frequency comb 

output from a femtosecond fi ber laser,” IEEE J. Quantum 

Electron., Vol. 41, No. 11, pp. 1–16 (2005). 

R. Fox, B. R. Washburn, N. R. Newbury, L. Hollberg, “Wavelength references for interferometry in air,” Appl. Opt., Vol. 44, 

No. 36, pp. 7793–7801 (2005).

S. L. Gilbert, W. C. Swann, C. M. Wang, “Hydrogen cyanide 

H13C14N absorption reference for 1530 nm to 1565 nm wavelength calibration – SRM 2519a,” Special Publication (NIST 

SP) 260-137, 2005 Edition.

W. C. Swann, S. L. Gilbert, “Line centers, pressure shift, 

and pressure broadening of 1530-1560 nm hydrogen cyanide 

wavelength calibration lines,” J. Opt. Soc. Am. B, Vol. 22, No. 

8, pp. 1749–1756 (2005).

K. Kim, B. Washburn, G. Wilpers, C. W. Oates, L. W. Hollberg, N. R. Newbury, S. A. Diddams, J. Nicholson, M. F. Yan, 

“Stabilized frequency comb with a self-referenced femtosecond 

Cr:forsterite laser,” Opt. Lett., Vol. 30, No. 8, pp. 932–934 

(2005).

B. Washburn, R. W. Fox, N. R. Newbury, J. Nicholson, K. Feder, 

P. S. Westbrook, C. G. Jorgensen, “Fiber-laser-based frequency 

comb with a tunable repetition rate,” Optics Express, Vol. 12, 

No. 20, pp. 4999–5004 (2004).

B. Washburn, S. A. Diddams, N. R. Newbury, J. Nicholson, F. 

Kenneth, P. S. Westbrook, C. G. Jorgensen, “Infrared frequency 

comb for frequency metrology based on a tunable repetition 

rate fi ber laser,” Tech. Dig., Symp. on Optical Fiber Meas., Sep 

28–30, 2004, Boulder, CO, NIST Special Publication 1024, pp. 

11–14 (2004). 

W. C. Swann, S. L. Gilbert, “Accuracy limits for simple molecular absorption based wavelength references,” Tech. Dig., Symp. 

on Optical Fiber Meas., Sep 28–30, 2004, Boulder, CO, NIST 

Special Publication 1024, pp. 15–18 (2004).
Optoelectronics Division 23

NANOSTRUCTURE FABRICATION AND METROLOGY

Technical Contact:

Rich Mirin

Staffi ng (FY06): 

3.8 professionals 

6.5 associates

GOALS

Develop modeling, fabrication, and measurement 

methods for semiconductor nanostructures, including quantum dots and photonic crystals. Develop 

fundamentally new devices such as single-photon sources and detectors and entangled-photon 

sources.

CUSTOMER NEEDS

Semiconductor nanostructures, especially selfassembled quantum dots and photonic crystals, 

are emerging as an important future direction for 

optoelectronics. Photonic crystals offer a wide 

range of possibilities, ranging from improved 

light-emitting diodes to photonic integrated circuits 

to spontaneous emission control. Semiconductor 

quantum dots have an atomic-like density of states 

that offers substantial opportunities for unique and 

improved devices. These include ultra-low-threshold laser diodes with low temperature dependence, 

and semiconductor optical amplifi ers with reduced 

cross-gain modulation and large bandwidth. 

Several fundamental properties of quantum dots, 

including resonant absorption cross-sections and 

homogeneous linewidth, set limitations on device 

operation. For example, high-spectral-resolution 

measurement of quantum dots is important for 

quantifying structural homogeneity as well as providing data to model devices to be used in quantum 

information applications.

The ability to generate and control single photons 

offers new opportunities to meet customer needs in 

quantum-based radiometric measurements where 

optical power is measured by counting photons. 

Quantum cryptography is an emerging form of 

ultrasecure communications that requires an ondemand source of single photons as well as single 

photon detectors. The single-photon turnstile will 

allow us to meet the requirements of this new 

technology. It can be extended to generate pairs of 

entangled photons. These entangled-photon pairs 

are useful for a wide range of applications, from 

fundamental tests of quantum mechanics to reduced 

dimensions with optical lithography. Semiconductor single photon detectors with reduced timing 

jitter, higher quantum effi ciency, and photoresponse 

beyond 1000 nm offer advantages in applications 

such as semiconductor and integrated circuit characterization, LIDAR, and quantum cryptography.

TECHNICAL STRATEGY

GROWTH AND CHARACTERIZATION OF

SEMICONDUCTOR QUANTUM DOTS

We use molecular beam epitaxy (MBE) to grow 

self-assembled quantum dots. We have developed 

ultrafast pump-probe methods to characterize carrier lifetimes of quantum dots. We have used a 

novel time-resolved waveguide-coupling method 

to directly measure the dipole moment of quantum 

dots. Cavity ring-down spectroscopy provides an 

extremely sensitive direct measurement of absorption. Differential transmission spectroscopy yields 

information on carrier transfer and an estimate 

of the homogeneous linewidth of quantum dots. 

Spectral hole-burning techniques have been developed to directly measure the lineshape. 

PLAN: Directly measure the dependence of the 

homogeneous lineshape of semiconductor quantum 

dots on power and applied electric fi eld. Extend the 

operation of the spectral hole-burning experiment to 

single-dot absorption spectroscopy.

SINGLE PHOTON SOURCES

For practical implementation, single-photon 

sources should operate at high temperatures. 

Colloidal CdSe quantum dots, nitrogen vacancy 

centers, and single molecules have demonstrated 

room-temperature single-photon emission; however, the fi rst two systems exhibit blinking, and 

some single molecules exhibit photobleaching, 

both of which degrade performance. Epitaxial 

InGaAs/GaAs quantum dots are attractive as single 

photon emitters due to their ease of fabrication and 

inclusion with monolithic microcavities, their short 

spontaneous emission lifetimes, and the possibility 

of electrical injection.

The photon repetition rate of the single-quantumdot, single-photon turnstile (SPT) is controlled by 

the frequency of an applied AC voltage, allowing 

precisely defi ned emission of single photons. The 

ultimate goal is the embedding of an SPT inside 

a photonic crystal nanocavity, which will enable 

enhanced emission effi ciency and directionality. 

We have implemented a Hanbury Brown-Twiss 

apparatus to measure the photon statistics from our 

SPT. A true single-photon device exhibits photon 

emission times that are nonclassical. Specifi cally, 

photon antibunching has been observed.

PLAN: Demonstrate an electrically driven single photon 

turnstile based on a single quantum dot. Determine 

the path to application in quantum-based radiometry.
24 Electronics and Electrical Engineering Laboratory

SINGLE-PHOTON DETECTORS

Photon detectors made with fi eld-effect transistors 

(FETs) that use an optically addressable fl oating 

gate consisting of a layer of quantum dots have the 

potential to be fast, fl exible, and effi cient singlephoton detectors. With compound semiconductors 

one can control the absorption spectrum via material choices. In addition, resonant-cavity designs, 

which raise the effi ciency, are compatible with 

these structures.

PLAN: Optimize a single-photon detector consisting 

of an optically modulated, quantum-dot fi eld-effect 

transistor. The detector will be compact, of low noise, 

have a high quantum effi ciency (goal of greater than 

90 %), and have photon-number-resolving capability.

SEMICONDUCTOR PHOTONIC CRYSTALS

Photonic crystal cavities and waveguides are 

expected to play important roles in advanced optoelectronic devices such as ultracompact photonic 

integrated circuits for communication and sensing. 

The fabrication of photonic crystals requires the 

precision growth and anisotropic etching of semiconductor epilayers. We are using a chemically 

assisted ion-beam (CAIBE) system to etch semiconductor nanocavities in layers grown by MBE. 

These nanocavities contain quantum dots, and the 

spontaneous emission from the quantum dots is 

infl uenced by the effects of the cavity. Careful 

control of the cavity structure and the position of 

the quantum dots within the cavity can lead to weak 

coupling (enhanced spontaneous emission, also 

known as the Purcell effect) or to strong coupling 

(Rabi oscillations).

Semiconductor light-emitting diodes can effi ciently 

generate light throughout the ultraviolet, visible, 

and near-infrared. However, because of the high 

index mismatch at the semiconductor-air interface, 

only a small fraction of light in a conventional 

LED is extracted normal to the surface, the rest 

being emitted into the substrate, or trapped and reabsorbed in the active layer. The development of 

nanophotonic structures such as photonic crystals 

to enhance light extraction could offer superior effi ciency, integration, and cost over present efforts 

in LED chip shaping and packaging. We are using 

Bragg gratings to enhance the extraction effi ciency 

of light-emitting devices. Further application of 

on-chip gratings is to control dispersion in modelocked lasers.

PLAN: Investigate the application of photonic crystals 

to emission control in single-photon sources and other 

devices. Demonstrate dispersion compensation with 

chirped gratings to shorten pulse widths in monolithic 

mode-locked diode lasers.

MODE-LOCKED QUANTUM DOT LASERS

There are many applications of ultrashort/broadband optical pulses that are hindered by the cost, 

complexity and ineffi ciency of the large-frame 

mode-locked lasers used to produce such pulses. 

These include optical atomic clocks, terahertz 

generation for homeland security, and optical coherence tomography (OCT). The problems would 

be eliminated if high-performance mode-locked 

diode lasers could be developed. Efforts to develop mode-locked diode lasers ran up against a 

fundamental barrier that limited the brevity of the 

pulses — carrier dynamics in the gain region of 

semiconductor lasers that result in a complex phase 

profi le of the generated pulse. Ultimately 200 fs 

pulses have proven to be the shortest achievable 

from a conventional mode-locked diode laser, i.e., 

one that uses a simple heterojunction or quantum 

well(s) for the gain region. This falls well short 

of the performance (~20 fs pulses) required for the 

most promising applications.

We plan to overcome this fundamental barrier by 

utilizing self-organized quantum dots for the gain 

region. It is anticipated that the quantum dots will 

be immune to the deleterious effects of complex 

carrier dynamics and enable a major improvement of pulse durations. In addition, the inherent 

size distribution in self-assembled QD ensembles 

leads to a very large inhomogeneously broadened 

lineshape with the bandwidth necessary to support 

short-pulse mode locking. This project requires a 

close coupling between expertise in QD growth, 

semiconductor laser design and fabrication, and 

in ultrafast lasers and measurement.

PLAN: Develop mode-locked quantum-dot diode 

lasers, with an ultimate goal of 20 fs pulse width, and 

characterize their output.

QUANTUM OPTICAL METROLOGY

Many precision measurements of length or refractive index are based on interferometry. However, 

the phase resolution of these measurements scales 

as the reciprocal of the square root of the amount 

of optical power used for the measurement. This 

is not a fundamental limitation, however, and the 

goal of this new project is to explore optical interferometry at the fundamental Heisenberg limit, in 

which phase resolution increases as the reciprocal 

of the number of photons.

PLAN: Develop new sources of N entangled photons, 

such as NOON states and Schroedinger cat states, and 

use these to peform interferometry.
Optoelectronics Division 25

ACCOMPLISHMENTS

Optically/electrically pumped photon emitter

— Demonstrated prototype device as an important 

step toward a hybrid optically/electrically pumped 

single photon emitter. Holes were optically injected 

by absorption of ~ 800 nm wavelength light in a 

GaAs layer and stored by an ensemble of InGaAs 

quantum dots. This was followed by forward 

biasing to inject electrons into the quantum dots, 

and subsequent photon emission at 950-1000 nm 

wavelength. Current research is on reducing the 

number of quantum dots used for the measurement 

and on increasing the collection effi ciency through 

use of a transparent contact.

Homogeneous linewidth of quantum dots 

measured — Developed and applied a pump-probe, 

spectral-hole-burning technique to directly measure, with high spectral resolution, the exciton homogeneous absorption linewidth of self-assembled 

InGaAs quantum dots. The technique uses a local 

oscillator to separate detection of the collinear 

pump and probe beams in the waveguide geometry. 

Pump-power-dependent and temperature-dependent data were collected and modeled. 

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High-resolution spectroscopy of InGaAs/GaAs quantum dots: full width at half maximum of the spectral 

hole vs. pump power through the waveguide at 9 K.

Quantum dot coherence time measured — 

Used high resolution spectral hole burning (SHB) 

to perform the best measurements of InGaAs/GaAs 

quantum dot coherence time to date. The measured 

linewidth is nearly spontaneous-emission-lifetime 

limited. The SHB method used enabled a measurement of coherence time of 1.76 ns, which is a factor 

of two longer than other groups have reported, and 

makes quantum dots more attractive candidates as 

qubits in quantum logic operations.

■

Semiconductor single photon detector with 

high quantum effi ciency — Demonstrated single 

photon detection using a quantum-dot-gated, fi eld 

effect transistor (QDOGFET). The detector exhibits time-gated, single-shot, single-photon sensitivity; a linear response to average photon number; 

and an internal quantum effi ciency of 70 % at 4 K 

through careful design to effi ciently detect photons 

absorbed in the GaAs absorbing layer. The noise 

in the system was reduced to ~ 0.5 photons (1/e), 

opening the possibility of developing a photon 

number resolving detector. 

Single photon source characterized with lowjitter superconducting detector — Demonstrated, 

with the Quantum Information and Terahertz Technology Project, the fi rst use of superconducting 

single-photon detectors (SSPDs) for single-photon 

source characterization. The source was an optically pumped, microcavity-coupled, InGaAs quantum 

dot, emitting single photons at 902 nm. The two 

SSPDs replaced the silicon Avalanche Photodiodes 

(APDs) in a Hanbury-Brown Twiss interferometer 

measurement of the source second-order correlation function. The SSPD system electronics jitter 

was 68 ps, versus 550 ps for the APD units, allowing the source spontaneous emission lifetime to be 

measured with improved resolution. 

Time-correlated infrared single-photon counting with superconducting detector — Demonstrated, with the Quantum Information and Terahertz 

Technology Project, the advantages of a NbN-based 

superconducting single photon-detector (SSPD) in 

a time-correlated, single-photon counting scheme 

to measure short spontaneous emission lifetimes 

of quantum wells in the infrared. The instrument 

response function (IRF) of the SSPD was shown 

to be Gaussian over nearly 5 decades of dynamic 

range. The FWHM of the IRF, which is a measure 

of the timing jitter, was 68 ps. These response 

characteristics are of great advantage over those 

of Si avalanche photodiodes (APDs) for detailed 

measurement of emission decay curves with high 

temporal resolution. In contrast, the IRFs of Si 

APDs exhibit long tails and multi-component 

responses. Quantum well emission out to 1650 

nm in wavelength was measured with the SSPD, 

well beyond the photosensitive range of Si. APDs 

based on InGaAs or Ge can have reasonable detection effi ciencies in the infrared, but are limited in 

available dynamic range.

Light extraction effi ciency greatly enhanced 

— Demonstrated enhanced light extraction from 

circular Bragg grating-coupled semiconductor microcavities. A distributed Bragg refl ector 

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26 Electronics and Electrical Engineering Laboratory

(DBR), behind the InGaAs quantum dot emitters 

and consisting of high-index-contrast GaAs/AlOx 

layers, increased the integrated photoluminescence 

by a factor of 2.7 over that of a device with no 

oxide DBR, indicating the role of the vertical cavity in enhancing extraction effi ciency. To extract 

guided emission otherwise trapped in the plane of 

the device, circular Bragg gratings (CBGs) were 

formed on the periphery of the light-emitting mesa 

my means of a chlorine-assisted, ion-beam etch. 

Mode extraction was maximized by near-perfect 

momentum matching of the guided circular cavity modes to the resonant-extracted modes of the 

vertical cavity. The effect of the CBGs was an 

additional measured 7.5 times enhancement of 

light extraction, yielding a calculated absolute 

external effi ciency of 41 % for the whole device. 

The modeling of modal dispersion diagrams and 

light extraction aided the design of the devices 

and interpretation of the data. The development 

of nanophotonic structures such as the DBR/CBG 

device offers potential advantages in effi ciency, 

integration, and cost over present LED chip shaping and packaging for display and biomedical 

applications.

Circular Bragg grating device for light extraction 

effi ciency enhancement.

Yale University: nanomechanical resonators.

NIST Physics Laboratory: quantum state tomography.

RECENT PUBLICATIONS

M. Stevens, R. Hadfi eld, R. Schwall, S. W. Nam, R. Mirin, “Fast 

lifetime measurements of infrared emitters using a low-jitter 

superconducting single-photon detector,” Appl. Phys. Lett., Vol. 

89, No. 031109 (2006).

J. J. Berry, M. Stevens, R. Mirin, K. L. Silverman, “High-resolution spectral hole burning in InGaAs/GaAs quantum dots,” 

Appl. Phys. Lett., Vol. 88, No. 061114 (2006).

K. L. Silverman, J. J. Berry, R. Mirin, “High-resolution continuous-wave absorption measurements on InGaAs/GaAs self-assembled quantum dots,” The Proceedings of the state-of-the-art 

program on compound semiconductors XLIV, May 07–12, 2006, 

Denver, CO (2006).

M. Su, R. Mirin, “Enhanced light extraction from circular Bragg 

grating coupled microcavities,” Appl. Phys. Lett., Vol. 89, No. 

033105 (2006).

R. Hadfi eld, M. Stevens, S. Gruber, A. J. Miller, R. Schwall, R. 

Mirin, S. W. Nam, “Single photon source characterization with 

a superconducting single photon detector,” Optics Express, Vol. 

13, No.26, pp. 10846–10847 (2005).

K. L. Silverman, R. Mirin, S. T. Cundiff, B. Klein, “Carrier 

dynamics and homogeneous broadening in quantum dot waveguides,” Proc., SPIE, The International Society for Optical Engineering, Integrated Optoelectronic Devices 2005, Jan 24–25, 

2005, San Jose, CA, Vol. 5734, pp. 94–105 (2005).

R. Mirin, “Photon antibunching at high temperature from a 

single InGaAs/GaAs quantum dot,” Appl. Phys. Lett., Vol. 84, 

No. 8, pp. 1260–1262 (23-Feb-2004).

K. L. Silverman, R. Mirin, S. T. Cundiff, “Lateral coupling 

of InGaAs/GaAs quantum dots investigated using differential 

transmission spectroscopy,” Phys. Rev. B, Rapid Comm., accepted 2004.

KEY COLLABORATIONS

CU/JILA: development of mode-locked, quantum 

dot laser diodes; two-dimensional spectroscopy of 

coupled quantum wells.

Texas A&M University: nanolithography on GaAs 

for quantum dot position control and nanoantennas 

coupled to quantum dots. 
Optoelectronics Division 27

QUANTUM INFORMATION AND TERAHERTZ

TECHNOLOGY

Technical Contact:

Sae Woo Nam

Staffi ng (FY06): 

2.5 professionals

5.5 associates

GOALS

Develop superconducting single-photon and 

photon-number-resolving detectors and evaluate 

them in quantum communication networks and 

fundamental physics experiments. Develop and 

apply terahertz and millimeter-wave technology 

and metrology for imaging and spectroscopy.

CUSTOMER NEEDS

New quantum-based communication and measurement systems that use single and correlated photons 

have been developed; however, the current tools 

for calibrating the components in these systems 

are inadequate for the emerging applications. For 

accurate calibration, a detector capable of determining the number of photons in a single pulse of 

light is needed. We are developing high-effi ciency 

detector systems with this capability in the three 

telecommunication windows (850 nm, 1310 nm, 

and 1550 nm). These new instruments will also 

aid in the understanding and advancement of new 

photon sources such as the single-photon turnstile 

and entangled photon sources. They can be used as 

a spectroscopic diagnostic tool or characterization 

tool for optical elements, optical materials, and 

optical systems at ultralow light levels. A near-term 

use of the detectors is for research in quantum key 

distribution, a method of communication where security is assured by the laws of quantum mechanics 

rather than by mathematical complexity.

Imaging in the ~100 GHz to ~2 THz range offers 

the possibility of concealed weapons detection and 

remote detection of contraband (for example, explosives under clothing) without the use of ionizing 

radiation. Spectroscopy in this frequency range 

has additional applications in industrial processing 

and remote identifi cation of chemicals. Industry 

and government agencies require unique capabilities in detectors, optics, and metrology methods 

and test-beds for improved imaging systems and 

unbiased, calibrated evaluations of systems and 

components. 

TECHNICAL STRATEGY

TRANSITION-EDGE SENSOR

Superconducting transition-edge sensor (TES) 

detector technology is suited for counting photons 

at telecommunication wavelengths or measuring 

the energy of a single photon. In this device a thin 

fi lm of tungsten is cooled to its superconducting 

transition temperature (~100 mK). The tungsten 

is biased at its transition from the normal to superconducting state such that the input of a small 

amount of heat, for example from the arrival of a 

single infrared photon, dramatically changes the 

tungsten resistance. The change in resistance is 

proportional to the heat absorbed.

These TES detectors can be operated in two distinct 

modes depending on the photon source properties. 

For single-wavelength (monochromatic) sources 

such as lasers and spontaneous parametric downconversion crystals (used for quantum information 

and metrology), the sensor response is directly 

proportional to absorbed photon number (photon 

number discrimination mode). For broadband 

sources (such as white-light or multiple fl uorescence emissions) the energy-resolving ability of 

the TES devices allows photon-counting spectroscopy to be performed across the entire nearinfrared/optical band (2 μm to 200 nm). In this 

mode, the photon number is discarded in favor of 

determining the energy of the incoming photons 

(spectroscopic mode).

We have increased the quantum effi ciency of the 

TES detector system to over 85 % by incorporating 

the tungsten fi lm in a carefully designed “optical 

cavity.” Additional improvements will use dielectric mirrors and methods to reduce fi ber coupling 

loss. Our goal is to get as close to 100 % overall 

system effi ciency as possible. Our long-term goal 

for reduced recovery time of the TES detector is 10 

ns. Research on new materials and improved electronic readout schemes may help in this regard.

Conventional semiconductor-based single-photon 

detectors suffer from high rates of “dark counts” 

(false positives), at the communication wavelengths of 1300 nm and 1550 nm, which severely 

limit single-photon applications. The TES detectors have no intrinsic dark counts, allowing them 

to be operated at much lower light levels than any 

existing metrological instrument. As the effi ciency 

of TES systems has increased this has led to the 

investigation of previously unknown sources of 

dark counts in fi ber optic systems.

Their unparalleled sensitivity allows these detectors to be a signifi cant tool in the development 

of quantum-based communication protocols and 

the evaluation of the security of optical quantum 
28 Electronics and Electrical Engineering Laboratory

cryptographic systems, which we carry out in collaboration with government and industry partners. 

Technology transfer is an important part of our 

strategy.

PLAN: Increase detection effi ciency of TES systems to 

over 92 % using dielectric mirrors and improved fi ber 

coupling. Reduce detector recovery time to 100 ns by 

use of new materials and electronic readout schemes.

SUPERCONDUCTING SINGLE PHOTON

DETECTOR

Superconducting single photon detectors (SSPDs) 

incorporate a very narrow (~100 nm) serpentine 

line of metallic superconductor such as Nb or NbN 

carrying a bias current very close to its critical current. When a photon strikes the superconductor a 

small “hot spot” is created locally, reducing the 

critical current to a value below the bias current. 

This creates an easily detected voltage across the 

superconductor. While the detector is not photon 

number resolving (one or more photons will create 

the hot spot), it is extremely fast, producing pulses 

of order a few tens of nanoseconds. Such a device 

is potentially very useful in a quantum communication system. At the present time, it is diffi cult to 

couple light to these devices with high effi ciency 

because of their small size (3 micrometer x 3 

micrometer), and they are incapable of long-term 

unattended stable operation. We are working to address both of these issues, including improvement 

of in-house fabrication capabilities, novel device 

designs, and development of techniques to reduce 

timing jitter. We are integrating SSPDs in compact 

cryocoolers and using them in quantum key distribution links, in long-wavelength, time-resolved, 

semiconductor nanostructure spectroscopy, and in 

the characterization of single-photon sources.

PLAN: Develop in-house NbN fi lm deposition 

techniques suitable for designing devices that are 

embedded in optical layers so that the detection 

effi ciency can be >80 %. Work with groups inside and 

outside of NIST on the fabrication of fi lms into devices. 

Demonstrate use of these detectors in a cryogen-free 

system for quantum information, lidar, near-infrared 

time-correlated single-photon studies, and time-of-fl ight 

experiments.

QUANTUM OPTICAL METROLOGY

Many of the highest precision optical measurements are based on interferometry. Examples 

include optical gyroscopes, gravity wave detectors, 

and optical coherence tomography. Traditionally, 

interferometers are usually limited by the photon 

noise (shot noise) of the laser beam or other classical light source that is used for interrogating the 

sample — the phase resolution scales as 1/sqrt(N), 

where N is the mean photon number of the laser. 

In conventional interferometry, the uncertainty 

in the measurement is proportional to 1/sqrt(N) 

because each photon carries independent measurement information. However, recently it has been 

pointed out that with a properly prepared quantum 

state of light (properly prepared N-photon state) as 

the input to our interferometer, we can do Heisenberg-limited interferometry, with a resolution 

proportional to 1/N. By using proper photon state 

preparation and detection, the N photons are no 

longer independently measuring the interference. 

Rather, these entangled photons act in unison to 

perform the measurement. Hence, there is a potentially large improvement in the accuracy of the 

measurement. 

We will leverage our existing expertise in singlephoton on-demand sources, parametric downconversion sources of entangled photon pairs, 

and photon number resolving (PNR) detectors 

to generate and detect new quantum states of 

light. We are developing schemes for generating 

N-photon states, more formally known as Fock 

states or photon number states, superpositions of 

Fock-states (N photons in mode a and 0 photons 

in mode b superimposed with 0 photons in mode a

and N photons in mode b, i.e., NOON states) and 

superpositions of coherent states of light, often 

called “cat states.” 

We also plan to develop a quantum optical metrology (QOM) testbed where we can attempt to use 

these new states of light. Examples of possible 

QOM include Heisenberg limited interferometry, 

quantum optical coherence tomography (OCT), 

quantum ellipsometry, and quantum lithography. 

At present, it is unlikely that any of these techniques will exceed the performance of standard 

techniques, but investigation of the performance 

limitations of their quantum counterparts will be 

important.

PLAN: Generate N-photon states with quantum 

dot sources and generate cat states with photonnumber resolving detectors. Explore NOON state 

interferometry.

TERAHERTZ TECHNOLOGY

Over the past several years this project has focused 

on bolometric detectors, initially developed for 

cryogenic electronic applications, but also useful 

in the detection or frequency conversion of radiation from millimeter to infrared wavelengths. The 

work on cryogenic detectors has been extended 

to antenna-coupled bolometers operating at room 

temperature. These detectors provide a rugged, 
Optoelectronics Division 29

low-cost alternative for Homeland Security applications, for example mobile police units or 

portal scanners in airports. We have systematically 

investigated the transmission between 100 GHz 

and 1 THz of materials commonly used in clothing 

and have established that imaging in this frequency 

range has the potential for effectively detecting 

weapons and contraband concealed by clothing. 

We fabricated a wafer-scale 120-element focal 

plane array of antenna-coupled bolometers and 

demonstrated real time imaging. We have also 

investigated the effi ciency of various illumination 

schemes establishing the viability of actively illuminated imagers in portal applications. 

PLAN: Continue to explore applications of uncooled 

antenna-coupled microbolometers. Perform side-byside imaging of the same scenes with passive (see 

below) and actively illuminated terahertz camera 

systems. This will help settle many outstanding 

phenomenological questions, for example, on capability 

of terahertz systems to selectively identify specifi c 

target materials.

MICRO-ANTENNA TESTING FACILITY

The program continues to improve antenna-coupled 

bolometric detectors and was charged by DARPA 

to establish facilities and protocols for testing antenna-coupled components developed in industry. 

Many of the detectors developed in academia and 

industry are antenna-coupled, and our prior microantenna array experience indicates that the greatest remaining obstacle to uniform and systematic 

comparison of microantenna device performance 

lies in unambiguous measurement of coupling effi -

ciencies. This in turn requires amplitude and phase 

pattern measurement of the microantennas, which 

is diffi cult to do with conventional techniques at 

high frequency because of errors introduced by 

moving cables. We have built an all quasi-optic test 

setup for measurement of complex millimeter-wave 

antenna patterns. This complex pattern data can 

then be incorporated into a comprehensive analysis 

of coupling effi ciency for each device tested. The 

complex antenna setup is scalable to terahertz and 

infrared frequencies because of the quasi-optic 

nature of the coupling. 

Two other metrics that are frequently needed for 

uniform and systematic comparison of device 

performance are NETD and spatial resolution. We 

are developing a radiometric temperature reference 

(Aqueous Blackbody Calibration or ABC source) 

and spatial resolution targets for calibration of 

terahertz imaging systems.

PLAN: Thoroughly characterize the capabilities of the 

terahertz microantenna range, the ABC source, and 

the spatial resolution targets, and publish the results 

and instructions on their use. Distribute copies of the 

ABC source, and possibly of the spatial resolution 

targets, to interested measurement laboratories. The 

terahertz microantenna range will remain available 

for pattern measurements on non-NIST microantenna 

devices from the DARPA MIATA (Micro Antenna Arrays: 

Technology and Applications) program and elsewhere.

PASSIVE MILLIMETER-WAVE/TERAHERTZ

IMAGING

When cooled to below the superconducting transition temperature of the bridge material, airbridge 

microbolometers provide extraordinary sensitivity as millimeter-wave and terahertz detectors, 

sensitivity far beyond the current state of the art 

for uncooled detectors. This sensitivity enables 

mmw/THz imaging for effective concealed weapons detection that is completely passive, using only 

the ambient blackbody emission of the target and 

background. Moreover, the high speed of superconducting antenna-coupled microbolometers enables mechanically scanned camera architectures, 

which eliminates the need for complex and expensive multiplexing and amplifi cation schemes in the 

focal plane. These advantages of superconducting antenna-coupled microbolometers have been 

demonstrated in single-pixel experiments on Nb 

(and to a lesser extent NbN) microbridges, and in 

a signifi cant amount of passive indoor imagery obtained with a raster-scanned optical setup. Detector 

NETD (noise-equivalent temperature difference) 

levels as low as 120 mK have been demonstrated, 

well below the typical level of temperature fl uctuations in ambient indoor environments.

The current plan is to extend the single-pixel imaging to a full-scale mmw/THz imager that operates 

in real time over a 2m x 4m fi eld of view at a 5 m 

to 10 m range. This will be done by building a 

linear, 128-element microbolometer array using the 

same detector architecture as for the single pixel. 

A mechanical scanning optic will provide spatial 

coverage in the orthogonal direction. The array 

would be mounted in a commercial closed-cycle 

cryocooler. Readout would be performed with entirely room-temperature electronics, using a novel 

transimpedance feedback scheme developed by 

our collaborators in VTT (Helsinki) that does not 

add noise above the intrinsic detector noise level. 

The Transportation Security Administration (TSA) 

Laboratory is funding the work.

PLAN: Extend the single-pixel imaging to a full-scale 

millimeter wave/terahertz imager that operates in real 

time. Deliver copy of scanned imager to the TSA 

Laboratory.
30 Electronics and Electrical Engineering Laboratory

ACCOMPLISHMENTS

Record effi ciency and QKD demonstrated with 

TES single-photon detector — Achieved a record 

88 % quantum effi ciency in a superconducting 

transition-edge sensor (TES), single-photon detector at 1550 nm, the highest quantum effi ciency of 

detection for near-infrared photons in the world. 

Also, in collaboration with researchers at Los Alamos National Laboratory, demonstrated quantum 

key distribution (QKD) at 1550 nm using TES 

detectors with negligible dark-count rates. Clock 

synchronization between the sender and receiver 

was achieved with either a bright optical pulse or 

an electrical signal. The minimum value of mean 

photon number achieved for a fi ber link length of 

50 km was used to calculate a maximum distance 

of 138 km over which one can transmit secret key 

with the QKD system using a mean photon number of 0.1. The group used bent-fi ber fi ltering of 

blackbody photons to lower the TES dark-count 

rate, which is not intrinsically limited, unlike that 

in other types of detectors. By use of narrowband 

fi ltering, it is estimated that one could distribute key 

securely over a link greater than 250 km.

Record QKD lengths demonstrated — Demonstrated QKD of record lengths in fi ber using a 

Transition-edge sensor with Los Alamos National 

Laboratory. For QKD systems utilizing BBBSS91 

privacy amplifi cation, we demonstrated a link of 

185 km. For a QKD system that is secure from 

photon-number splitting attack, using a weak 

coherent source, we demonstrated a fi ber link of 

68 km. For a QKD link that implements a decoy 

state protocol for security, we have demonstrated 

a link of 108 km.

Single photon source characterized with 

superconducting detector — Demonstrated, with 

the Nanostructure Fabrication and Metrology 

Project, the fi rst use of superconducting singlephoton detectors (SSPDs) for single photon source 

characterization. The source was an optically 

pumped, microcavity-coupled InGaAs quantum 

dot, emitting single photons at 902 nm. The two 

SSPDs replaced the silicon Avalanche Photodiodes 

(APDs) in a Hanbury-Brown Twiss interferometer measurement of the source’s second-order 

correlation function. The detection effi ciency of 

the superconducting detector system was greater 

than 2 % (coupling losses included). The SSPD 

system electronics jitter was 68 ps, versus 550 ps 

for the APD units, allowing the source spontaneous 

emission lifetime to be measured with improved 

resolution. SSPDs offer single-photon counting 

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at fast rates, low jitter, and low dark counts, from 

visible wavelengths well into the infrared. 

Time-correlated single-photon counting with 

superconducting detector — Demonstrated, in collaboration with the Nanostructure Fabrication and 

Metrology Project, the advantages of a NbN-based 

superconducting single-photon detector (SSPD) in 

a time-correlated, single-photon counting scheme 

to measure short spontaneous emission lifetimes 

of quantum wells in the infrared. The instrument 

response function (IRF) of the SSPD was shown to 

be Gaussian over nearly fi ve decades of dynamic 

range. The FWHM of the IRF, which is a measure 

of the timing jitter, was 68 ps. These response 

characteristics are of great advantage over those 

of Si avalanche photodiodes (APDs) for detailed 

measurement of emission decay curves with high 

temporal resolution. In contrast, the IRFs of Si 

APDs exhibit long tails and multicomponent responses. Quantum well emission out to 1245 nm 

in wavelength was measured with the SSPD, well 

beyond the photosensitive range of Si. APDs based 

on InGaAs or Ge can have reasonable detection 

effi ciencies in the infrared, but have limited available dynamic range. 

■

Instrument response functions of three detectors: SSPD — open circles; conventional Si APD 

— dashed; and fast Si APD — dotted curve. The solid 

curve is a Gaussian fi t to the measured SSPD response 

function.

High-speed QKD demonstrated with superconducting single photon detector — Demonstrated, 

in collaboration with a team of NIST Information 

Technology Lab and Physics Lab researchers, 

the operation of a superconducting single-photon 

detector (SSPD) system in a high-speed NIST 

quantum key distribution (QKD) link, which was 

originally equipped with silicon-based single photon detectors. The link operated at a system clock 

rate of 625 Mbps through 1 km of optical fi ber. 

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Optoelectronics Division 31

The laboratory system produced this “raw” sifted 

key at a rate of 1 million bits per second, roughly 

a quarter of the speed of NIST’s recently reported 

record-breaking performance. However, the error 

rate from this SSPD system was signifi cantly lower, 

1 % as opposed to 3.6 %. The lower error rate 

results in potentially more effi cient conversion of 

sifted key into secret key (75% vs 50%). The lower 

error rate is a direct result of lower jitter in this type 

of detector. Based on the results from this work, it 

should be possible to implement a QKD link with 

superconducting-based detectors at a clock rate fi ve 

times faster than the existing silicon-based detector 

system. If implemented, this would yield secret key 

at a new record rate. 

Record-low sensitivity millimeter-wave 

imaging system — Demonstrated a passive millimeter-wave imaging system with a net-equivalent-temperature-difference sensitivity of record 

0.13 K. The detectors are cryogenically cooled, superconducting antenna-coupled microbolometers. 

Images of contraband concealed under clothing 

were obtained, clearly demonstrating the potential 

for passive indoor imaging.

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Passive millimeter-wave image of concealed contraband.

Millimeter-wave monochromator — Demonstrated a novel, circular variable millimeter-wave 

monochromator spanning an octave in frequency, 

with interchangeable ranges. Measured a spectral 

resolving power of 6, reasonably well matched to 

the width of recently reported spectral signatures 

of solid explosives, with less than 0.5 dB insertion 

loss, Because microbolometers are inherently 

ultrawideband, such a monochromator enables true 

terahertz color imaging from a microbolometerbased camera.

Millimeter-wave detector testing — Completed the Phase I testing of millimeter-wave detector 

arrays for the DARPA MIATA program. Measure-

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ments of noise spectral density and responsivity to 

blackbody temperature changes enabled the most 

direct and accurate measurement of the noiseequivalent temperature difference for the zero-bias 

diode and optical modulator-based detectors from 

the industry and university participants in the 

program. Coherent measurements using a sweptfrequency monochromatic source were made to 

determine spectral responsivity over the W-band 

(75 to 110 GHz), and antenna patterns were also 

measured for some of the detectors using the NIST 

mm-wave/terahertz antenna range developed by 

project members. DARPA benefi ts signifi cantly 

from the neutral third-party testing role that NIST 

performs for this program. The detector technology 

has potential application in areas such as helicopter 

navigation, fi refi ghting, and concealed weapons 

detection. 

KEY COLLABORATORS

Hughes Research Laboratory – terahertz detector 

development and characterization 

University of Delaware – terahertz detector development and characterization

Northrup Grumman – terahertz detector development and characterization

Rockwell Sciences Center – terahertz detector 

development and characterization 

VTT, Finland – terahertz detector development and 

characterization

University of California, Santa Barbara – terahertz 

detector development and characterization

University of Colorado, Boulder – terahertz detector development and characterization

Los Alamos National Laboratory – quantum key 

distribution

BBN Technologies – quantum key distribution

Boston University – single-photon detector development

Sandia National Laboratory – single-photon detector development

Northwestern University – applications of singlephoton detectors

Heriot-Watt University – applications of singlephoton detectors

Massachusetts Institute of Technology – singlephoton detector development
32 Electronics and Electrical Engineering Laboratory

MIT-Lincoln Laboratory – single-photon detector 

development

Jet Propulsion Laboratory – applications of singlephoton detectors

RECENT PUBLICATIONS

A. Luukanen, E. N. Grossman, A. J. Miller, P. Helisto, J. S. 

Penttila, H. Sipola, H. Seppa, ”An ultra-low noise superconducting antenna-coupled microbolometer with a room temperature 

read-out,” IEEE Microwave and Wireless Comp. Lett., Vol. 16, 

pp. 464–466 (2006).

M. Stevens, R. Hadfi eld, R. Schwall, S. W. Nam, R. Mirin, “Fast 

lifetime measurements of infrared emitters using a low-jitter 

superconducting single-photon detector,” Appl. Phys. Lett., Vol. 

89, No. 031109 (2006).

D. Rosenberg, A. Lita, A. J. Miller, S. W. Nam, R. Schwall, 

“Performance of photon-number resolving transition-edge sensors with an integrated 1550 nm resonant cavity,” IEEE Trans. 

Appl. Supercond., Vol. 15, No. 2, pp. 575–578 (2005).

R. Hadfi eld, M. Stevens, S. Gruber, A. J. Miller, R. Schwall, R. 

Mirin, S. W. Nam, “Single photon source characterization with 

a superconducting single photon detector,” Optics Express, Vol. 

13, No. 26, pp. 10846–10847 (2005).

D. Rosenberg, S. W. Nam, P. A. Hiskett, C. G. Peterson, R. J. 

Hughes, J. E. Nordholt, A. Lita, A. J. Miller, “Quantum key 

distribution at telecom wavelengths with noise-free detectors,” 

Appl. Phys. Lett., Vol. 88, 021108 (2006).

D. Rosenberg, A. Lita, A. J. Miller, S. W. Nam, “Noise-free 

high-effi ciency photon-number-resolving detectors,” Phys. Rev. 

A, Vol. 71, 061803(R) (2005).

R. Hadfi eld, A. J. Miller, S. W. Nam, E. N. Grossman, R. 

Schwall, “Antenna coupled niobium bolometers for 10 (μ)m 

radiation detection,” IEEE Trans. Appl. Supercond., Vol. 15, 

No. 2, pp. 541–544 (2005).
Optoelectronics Division 33

OPTICAL MATERIALS METROLOGY

Technical Contact: 

Norman Sanford

Staffi ng (FY06): 

2.3 professionals

3 associates

GOALS

Develop complementary metrology methods 

of nonlinear optical analysis, near-fi eld optical 

spectroscopy, confocal microscopy, time-resolved 

photoluminescence, and X-ray diffraction analysis 

for studies of optical, electronic, and structural 

properties of bulk and thin-fi lm III-nitrides, quantum nanowires, and nitride device structures. Develop prototype nanowire devices. Accumulate a 

database of refractive index and birefringence for 

AlGaN and InGaN alloy semiconductors and rareearth-doped III-nitrides. 

CUSTOMER NEEDS

Customer needs fall into two main categories: 

metrology suites for rapid non-destructive characterization of photonic materials in terms of optical, electronic, and structural characteristics for 

bulk crystals and thin fi lms; and semiconductor 

nanowire technology and metrology for sensing, 

biomedical, materials science and electronics applications.

Gallium nitride and related materials have made 

enormous recent economic impact with the realization of semiconductor lasers and LEDs emitting in 

the blue and UV for display, optical data storage, 

water purifi cation, and biological agent detection. 

Other important applications of this material system 

include high-power, high-temperature transistors 

and solar-blind UV detectors. Problems with bulk 

and thin-fi lm growth of these materials remain, 

however, hindering the ability to meet the application demands. There persists a fundamental 

lack of understanding of the role of defects on the 

electrical, optical, and structural properties of these 

materials. These issues compel the development of 

new correlated metrology methods, with resolution 

on the scale of 20 to 100 nm. Furthermore, the 

lack of a database for the linear optical properties 

of the III-nitrides is hampering development of 

engineering design tools for blue-emitting GaNbased laser diodes.

Semiconductor quantum nanowires (SQNWs) offer 

new revolutionary applications in biological/chemical sensors, in-vivo biomedical diagnostics and 

therapies, nanoscale electronics, optoelectronics, 

and nanoscale thermal management. For example, 

SQNW lasers with emission apertures roughly 

20–100 nm in diameter (about the size of a virus) 

would permit development of a new class of tools 

for ultra-high-resolution microscopy and cellularlevel imaging. In pursuing such new capabilities, 

researchers and technologists must confront the 

facts that fundamental physical properties do not 

often scale from macro to nano regimes, and that 

many relevant nanoscale metrology practices are 

immature or nonexistent. For SQNWs, these issues 

force an unusually strong coupling of technology 

development with metrology, and create new challenges and opportunities for both. 

TECHNICAL STRATEGY

SPECTROSCOPY OF GROUP III-NITRIDES

Multiphoton luminescence (MPL) spectroscopy 

offers a means by which the uniformity of an active (buried) quantum well layer in a III-nitride 

laser or LED structure can be probed regardless of 

the thickness of the surrounding layers. Standard 

direct above-bandgap photoluminescence (PL) 

spectroscopy may often be problematic since the 

pump beam could be absorbed elsewhere in the 

structure before exciting the regions of interest. 

Using MPL spectroscopy, even embedded structures may be examined. Furthermore, it has been 

demonstrated that MPL intensity in GaN that scales 

with a non-integer exponent of pump intensity is 

suggestive of the presence of saturable midgap 

defect states. We will correlate MPL measurements 

with cathode luminescence (CL) results, obtained 

when the capping layer is thin enough (~20 nm) to 

allow CL examination of the active region through 

the capping layer, and with those of more realistic 

device structure where the active layer is buried 

hundreds of nanometers within the structure. 

We will continue the development of collectionmode near-fi eld optical methods and examine the 

group III-nitrides using second-harmonic generation and photoluminescence spectroscopies on a 

resolution scale of 20 to 100 nm. Time-resolved 

photoluminescence is also a very important metric 

for examining material quality in the III-nitrides. 

We plan on putting more emphasis on building up 

capabilities in time-resolved PL and applying this 

tool to both nanowires and thin-fi lm III-nitrides. 

Additionally, we have recently added spectrally 

resolved photoconductivity to our suite of spectroscopy tools for examining nitride fi lms and 

nanowires. This technique will prove important 

for the examination of persistent photoconductivity 

in these materials, assist in the evaluation of alloy 

composition, and be important in the eventual development of Schottky, p-i-n, and heterojunction 

quantum well devices in nanowires. 
34 Electronics and Electrical Engineering Laboratory

PLAN: Correlate near-fi eld optical measurements and 

MPL studies with CL studies and other high-resolution 

electron-beam and X-ray metrologies, working closely 

with collaborators in the NIST Materials Science and 

Engineering Laboratory (MSEL). Apply nanoscale 

spatially and temporally resolved spectroscopy to 

the study of AlGaN and InGaN material, thin fi lm 

structures, and nanowires fabricated in wide-bandgap 

semiconductors. Develop and apply spectrally resolved 

photoconductivity to the study of III-nitride fi lms, 

nanowires, and III-nitride optoelectronic devices.

ELECTRICALLY ADDRESSABLE

OPTOELECTRONIC NANOWIRES

We will fabricate UV-blue LEDs and lasers from 

SQNWs. The SQNWs will be grown in the group 

III-nitride semiconductor system by plasma-assisted MBE and/or chemical beam epitaxy. Required attributes include high purity, low defect 

density, the ability to engineer heterostructures 

and make electrical contact, and precise doping 

control. A suite of test structures will be developed 

that will include intrinsic, p- and n-doped wires, 

“core-sleeve,” and axially alternating junction/heterostructures of SQNWs. We will develop new 

techniques for selective area growth (these may 

involve block-copolymers or other high-resolution lithography methodology that will allow the 

formation of nanoscle templates) and apply these 

methods to the patterned growth of SQNWs. We 

will optimize techniques to form electrical contact 

individually or to arrays of SQNWs. We will use 

AFM, XRD, TEM, FESEM, Raman spectroscopy, 

and electron-backscattering diffraction (EBSD) for 

the structural characterization in this work.

PLAN: Demonstrate optically pumped group IIInitride nanowire lasers. After further development, 

demonstrate electrically addressable nanowire 

LEDs and lasers. Also, develop individual nanowire 

mechanical resonator structures for use as sensors; 

measure mechanical and piezoelectric properties

REFRACTIVE INDEX MEASUREMENTS OF

GROUP III-NITRIDES

We have compiled refractive index and birefringence data for a number of AlGaN samples ranging 

in composition from pure GaN to Al0.66Ga0.24N, using prism coupling to waveguide mode techniques 

that are correlated with spectroscopic refl ection 

and transmission measurements (performed by 

collaborators in MSEL). Furthermore, the Al mole 

fraction of this sample set was separately determined by analytical electron microscopy. We also 

have measured refractive index of InGaN for low 

In mole fractions of technological interest. There 

is new interest in extending this work to examine 

the refractive index of rare-earth-doped GaN and 

AlGaN at telecom wavelengths.

PLAN: Measure the refractive index of Er-doped GaN 

and AlGaN in the visible and near-infrared using an 

improved prism coupling setup.

ACCOMPLISHMENTS

Isolation and alignment of nanowires — Established methods to disperse and isolate gallium 

nitride nanowires on silicon and sapphire substrates 

using solvents. Demonstrated electric-fi eld-assisted alignment of nanowires between metal fi ngers, 

enabling electrical contacts and the fabrication of 

nanowire bridge structures.

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Gallium nitride nanowire bridge.

X-ray characterization of wide bandgap fi lms 

and nanowires — Compiled ‘a’ and ‘c’ lattice 

constants of GaN/InGaN and GaN/AlGaN fi lms, 

GaN nanowires, and ZnO nanowires by collecting 

and fi tting the data from symmetric and asymmetric X-ray diffractions. The samples were supplied in-house (MBE-grown nanowires from the 

Semiconductor Growth and Devices Project) or 

by government and industry collaborators. It was 

demonstrated through X-ray measurements that 

the in-house MBE-grown GaN nanowires are fully 

relaxed, aligned to the silicon substrate, and have 

a high degree of crystalline perfection.

High luminescence effi ciency demonstrated 

in nanowires — Demonstrated that the GaN 

nanowire ensembles grown by MBE have high 

photoluminescence effi ciency comparable to that 

of bulk GaN, without correction for the non-unity 

fi ll fraction of the nanowires. This further confi rms 

the low defect density of the nanowires.

Nanowire LED demonstrated — Codeveloped and demonstrated, with members of 

the Semiconductor Growth and Devices Project, 

the operation of an ultraviolet light-emitting diode 

based on gallium nitride nanowires. The LED 

demonstration required growth of isolated, lowdefect-density GaN nanowires on silicon, structural 

characterization as feedback to growth parameters, 

removal of the wires from the growth substrate and 

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Optoelectronics Division 35

dispersal on an n-type GaN substrate, optimization 

of electrical contacts, and spectroscopy of the LED 

output to verify emission from the nanowires. The 

LED emission center wavelength near 385 nm was 

believed to be the shortest wavelength demonstrated for this type of nanowire device at the time.

Photoluminescence anisotropy of gallium 

nitride nanowires characterized — Made polarization-resolved photoluminescence measurements, 

from 4 K to room temperature, of individual gallium nitride nanowires grown in-house by MBE. 

The wires were typically 5-10 um in length and 

30-100 nm in diameter. Details of the spectra 

varied from wire to wire but, in general, spectral 

peaks associated with free and bound exciton peaks 

of strain-free GaN were readily identifi ed. The 

nanowires enabled the fi rst unambiguous roomtemperature measurement of photoluminescence 

anisotropy from unstrained wurtzite gallium nitride 

that arises from the symmetry, band structure, and 

selection rules for radiative electronic transitions 

in the material. These measurements are diffi cult 

to perform in typical thin-fi lm gallium nitride or 

quasi-bulk free-standing platelets of the material 

but are readily enabled by the natural geometry and 

strain-free material offered by the nanowires. 

■

Photoluminescence spectra of GaN nanowire pair 

showing polarization anisotropy.

Single nanowire FETs demonstrated — Fabricated and tested single-nanowire, fi eld-effect transistors (FETs) from MBE-grown gallium nitride 

wires. The individual nanowires were dispersed and 

aligned to Ti pads on thermally oxidized Si, and 

e-beam-deposited Ti/Au ohmic contacts were made 

for the source and drain. Plasma etching before 

contact deposition proved to be critical in achieving low contact resistance. The back gate contact 

■

was aluminum. Drain current vs. voltage curves as 

a function of gate voltage were used to estimate 

electrical transport properties — mobility, carrier 

concentration, and carrier type — of the nanowires. 

This appears to be one of the few straightforward 

ways to measure these properties for nanowires, for 

which conventional Hall measurements cannot be 

made. Single nanowire bridge structures were also 

fabricated, and will be used for conformal coating 

of various passivation layers in future FET and 

photoluminescence work. 

Photoconductivity of nanowires measured

— Developed new apparatus for the measurement 

of spectrally resolved photoconductivity in nanowire structures. Initial results point to exploring the 

development of Schottky diode UV photodetectors 

based in III-nitride nanowires.

COLLABORATIONS

NIST Materials Science and Engineering Laboratory – TEM, EBSD, CL, and XRD studies of 

III-nitride fi lms and nanostructures, and studies of 

electrical contacts to these materials

University of Colorado — mechanical and optical 

measurements of nanostructures; atomic layer deposition coating of nanowires for surface reactivity 

modifi cations; biochemical sensors

National Renewable Energy Laboratory — coating 

nanowires with amorphous silicon to assist in p-n 

junction formation

Raytheon – study of GaN fi eld-effect transistors

RECENT PUBLICATIONS

J. B. Schlager, N. A. Sanford, K. A. Bertness, J. M. Barker, A. 

Roshko, P. T. Blanchard, “Polarization resolved photoluminescence study of individual GaN nanowires grown by catalyst-free 

MBE,“ Appl. Phys. Lett., Vol. 88, 213106 (2006).

K. A. Bertness, N. A. Sanford, J. M. Barker, J. B. Schlager, A. 

Roshko, A. V. Davydov, I. Levin, “Catalyst-free growth of GaN 

nanowires,” J. Electron. Materials, Vol. 35, pp. 576 (2006).

K. A. Bertness, A. Roshko, N. A. Sanford, J. M. Barker, A. V. 

Davydov, “Spontaneously grown GaN and AlGaN nanowires,“ 

J. Crystal Growth, Vol. 287, pp. 522 (2006).

J. E. Van Nostrand, K. L. Averett, R. Cortez, J. Boeckl, C. E. 

Stutz, N. A. Sanford, A. V. Davydov, J. D. Albrecht,“ Molecular 

beam epitaxial growth of high-quality GaN nanocolumns,“ J. 

Crystal Growth, Vol. 287, pp. 500 (2006).

I. Levin, A. Davydov, B. Nikoobakht, N. Sanford, P. Mogilevsky, “Growth habits and defects in ZnO nanowires grown 

on GaN/sapphiresubstrates,“ Appl. Phys. Lett., Vol. 87, 103110 

(2005).

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36 Electronics and Electrical Engineering Laboratory

N. A. Sanford, L. H. Robins, M. H. Gray, Y. –S. Kang, J. E. 

Van Nostrand, C. Stutz, R. Cortez, A. V. Davydov, A. Shapiro, 

I. Levin, and A. Roshko, “Fabrication and analysis of GaN 

nanorods grown by MBE,” Phys. Stat. Sol. (C), Vol. 2, 2357 

(2005).

N. A. Sanford, A. Munkholm, M. R. Krames, A. Shapiro, 

I. Levin, A. V. Davydov, S. Sayan, L. S. Wielunski, and T. 

E. Madey, “Refractive index and birefringence of InGaN 

fi lms grown by MOCVD,” Phys. Stat. Sol. (C), Vol. 2, 2783 

(2005).

N. A. Sanford, A. Davydov, D. V. Tsvetkov, V. A. Dmitriev, S. 

Keller, U. Mishra, S.P. DenBaars, S. S. Park, J. H. Han, “Measurement of second order susceptibilities of GaN and AlGaN,” 

J. Appl. Phys., Vol. 97, 053512 (2005).

L. H. Robins, B. Steiner, N. A. Sanford, C. Menoni, “Lowelectron-energy cathodoluminescence study of polishing and 

etching effects on the optical properties of bulk single-crystal 

gallium nitride,” Proc., Mater. Res. Soc. Symp., Dec 02–06, 

2002, Boston, MA, Vol. 743, pp. 213–218 (01-Jan-2003).

N. A. Sanford, L. H. Robins, A. Davydov, A. J. Shapiro, D. 

V. Tsvetkov, V. A. Dmitriev, S. Keller, U. K. Mishra, S. P. 

DenBaars, “Refractive index study of AlxGa1-xN fi lms grown 

on sapphire substrates,” J. Appl. Phys., Vol. 94, No. 5, pp. 

2980–2991 (01-Sep-2003).
Optoelectronics Division 37

SEMICONDUCTOR GROWTH AND DEVICES

Technical Contact: 

Kris Bertness

Staffi ng (FY06): 

2 professionals

4 associates

GOALS

Provide advanced materials and devices to support research in industry, other parts of NIST, 

universities and government laboratories. Develop 

measurement methods and provide data to support 

the effi cient manufacture of semiconductor nanostructures and optoelectronic devices.

CUSTOMER NEEDS

The continued growth of the U.S. optoelectronics 

industry is dependent on the high-yield manufacture of devices with smaller dimensions and tighter 

specifi cations. Compound semiconductor materials 

form the basis for LEDs, lasers, photodetectors, 

and modulators critical to optical communication, 

display, data storage, sensors, and many other applications. Many of these semiconductor devices now 

incorporate structures with a high degree of strain 

and nanostructures so small that the properties of 

the devices depend on their physical dimensions 

as well as the bulk materials properties. Measurements of starting materials, epitaxial layers, and 

nanostructured geometries must be supported by 

standard procedures and reference materials. Issues 

of materials purity and uniformity are at the foundation of device yield and performance. In addition, 

specialty devices are needed for use in metrology 

systems inside and outside of this project. 

TECHNICAL STRATEGY

SEMICONDUCTOR QUANTUM NANOWIRE

DEVELOPMENT

Semiconductor nanowires made from group IIInitrides are showing great promise for the next 

generation of high-efficiency, miniature light 

sources. Several research laboratories worldwide 

have demonstrated optically pumped lasing action 

in group III-nitride nanowires. To accelerate and 

support commercial development of these materials, we are growing nanowires made of GaN, 

AlN, InN and related alloys with ultra-low defect 

densities and high luminescence effi ciencies, and 

are pursuing fundamental studies of nanowire crystal growth using molecular beam epitaxy (MBE) 

and chemical beam epitaxy. Advanced structures 

incorporating quantum disks, axial alloy variation, 

and nucleation control are designed, grown, and 

characterized. Extensive high-resolution electron 

microscopy, scanning probe microscopy, and X-ray 

diffraction have shown that the wires are hexagonal 

in cross-section and strain-free, with a reproducible 

crystal orientation relative to the silicon substrates. 

Additional optical and structural characterization 

performed in collaboration with the Optical Materials Metrology Project and the NIST Materials 

Science and Engineering Laboratory also confi rms 

that the materials are essentially free of chemical 

impurities and structural defects. Nanowires have 

also been supplied to a number of collaborators 

within and outside of NIST. 

PLAN: Develop prototype optical and electronic 

nanowire devices for metrology, sensing, and 

other applications. Fabricate and characterize p-n 

heterostructure nanowires in the AlGaInN alloy system 

as progress towards the goal of demonstrating an 

electrically pumped group III-nitride nanowire laser.

STRUCTURAL CHARACTERIZATION AND

CONTROL OF QUANTUM DOTS AND

NANOWIRES

Quantum dots are semiconductor structures with 

quantized energy levels that result in improved effi ciency and tuning range for semiconductor lasers 

and less sensitivity to environmental changes for 

lasers and photodetectors. Dot formation is driven 

by strain during epitaxial crystal growth, but measuring the strain in structures less than 100 nm in 

lateral dimension presents new challenges. We 

have contributed to this fi eld through studies correlating substrate preparation and growth parameters 

with dot density and size as measured by atomic 

force microscopy (AFM). We are also evaluating 

the shape of the dots and strain in the region of 

the dots with transmission electron microscopy 

(TEM). In addition, we are studying ways to 

control growth of quantum dots and nanowires and 

improve uniformity using strain and appropriate 

growth conditions. 

PLAN: Examine the infl uence of strain on the 

formation and uniformity of quantum dots and 

nanowires. 

SEMICONDUCTOR COMPOSITION

STANDARDS DEVELOPMENT

Inaccuracy of semiconductor composition measurement has been an impediment to achieving 

consistency of device performance across production lines. It has also inhibited the collection of 

suffi ciently accurate materials parameters for use 

in the simulation of devices, which is critical to 

fast product cycle times. A goal of this project is 

to develop certifi cation techniques for standard 

reference materials having composition uncertainty specifi ed to a level one tenth as low as 
38 Electronics and Electrical Engineering Laboratory

that of techniques currently in use by industry. 

Our approach has been to combine conventional 

methods of determination of composition such 

as photoluminescence (PL) and X-ray diffraction (XRD) with less common methods (in situ 

monitoring, electron microprobe analysis (EMPA), 

and inductively coupled plasma optical-emission 

spectroscopy (ICP-OES)) to enable certifi cation 

of alloy composition. This program is the basis 

for the production of standard reference materials 

(SRMs) in the AlGaAs and AlInGaN alloy systems. 

As part of this research, we have quantifi ed error 

sources and accuracy limits of the indirect composition measurement techniques currently in use by 

industry, specifi cally PL and XRD. 

PLAN: Investigate the precision of measurement 

techniques necessary for the development of AlGaN 

composition standards.

SOURCE GAS PURITY MEASUREMENT

Contamination is a serious problem in phosphine, 

arsine, silane, ammonia, and similar gases used in 

the epitaxial growth of high-purity semiconductor 

layers. The critical concentrations of the impurities 

are not well known; however, it is believed that 

>10 nmol/mol oxygen or water in most process 

gases is undesirable. This project uses a cavity-ring-down spectroscopic (CRDS) system it 

developed with researchers in the NIST Chemical 

Science and Technology Laboratory to measure 

impurities with very low concentrations in semiconductor source gases. The advantages of this 

technique are that its accuracy relies primarily on 

accurate time measurement and detector linearity, 

rather than measurement of absolute light intensities, and it is insensitive to absorption outside the 

cavity. We have improved the detection limit of 

this system to 50 nanomol/mol of water in phosphine. We are using our system to measure the 

lineshape, absorption coeffi cients, and frequency of 

optical transitions for water, phosphine, ammonia, 

and arsine in the vicinity of 935 nm. This information is critical to facilitate the use of high-sensitivity 

spectroscopy techniques in these gases. The CRDS 

capability should ultimately lead to improvements 

in semiconductor source gas purity, which will 

allow crystal growers to choose less expensive 

growth conditions without sacrifi cing optical emission effi ciency and yield in LEDs, semiconductor 

lasers, and photodetectors. We collaborate with 

gas suppliers and purity instrumentation manufacturers in this project, including on-site testing of 

commercial instrumentation built to detect water 

in hazardous gases.

PLAN: Identify optimal spectral regions for 

measurement of water in phosphine, arsine and 

ammonia. Increase the sensitivity of our CRDS 

apparatus to the detection of water in these gases 

through the use of stronger absorption lines at longer 

wavelengths.

ACCOMPLISHMENTS

Gallium nitride nanowires grown — Demonstrated reproducible growth of isolated GaN 

nanowires 30 to 250 nm in diameter and 5 to 15 

micrometers in length using gas-source molecular 

beam epitaxy (MBE), without the use of metal catalysts. Low growth rates at substrate temperatures 

near 820 °C were combined with high nitrogen fl ux 

to form the wires, which grew out of an irregular 

matrix layer containing deep faceted holes. Xray and variable-temperature photoluminescence 

measurements, in collaboration with the Optical 

Materials Metrology Project, and transmission 

electron microscopy studies, in collaboration 

with the NIST Materials Science and Engineering 

Laboratory, showed that the GaN nanowires have 

a high degree of crystalline perfection. 

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MBE-grown gallium nitride nanowires.

Nanowire ultraviolet LED demonstrated

— Developed and demonstrated, in collaboration 

with the Optical Materials Metrology Project, 

operation of an ultraviolet light-emitting diode 

based on gallium nitride nanowires. The LED 

demonstration required growth of isolated, lowdefect-density GaN nanowires on silicon, structural 

characterization as feedback to growth parameters, 

removal of the wires from the growth substrate and 

dispersal on an n-type GaN substrate, optimization 

of electrical contacts, and spectroscopy of the LED 

output to verify emission from the nanowires. The 

LED emission center wavelength near 385 nm was 

believed to be the shortest yet demonstrated for this 

type of device at the time.

■
Optoelectronics Division 39

Single nanowire photoluminescence measured

— Grew GaN nanowires to enable variable-temperature, polarization-resolved photoluminescence 

measurements of individual wires. The nanowires 

enabled the fi rst unambiguous room-temperature 

measurement of photoluminescence anisotropy 

from unstrained wurtzite gallium nitride that arises 

from the symmetry, band structure, and selection 

rules for radiative electronic transitions in the 

material (see Optical Materials Metrology Project 

accomplishments).

Single nanowire FETs demonstrated — Collaborated with Optical Materials Metrology 

(OMM) Project in fabrication and demonstration 

of single-nanowire, fi eld-effect transistors (FETs) 

from MBE-grown gallium nitride wires (see OMM 

project for details). Drain current vs. voltage curves 

as a function of gate voltage were used to estimate 

electrical transport properties — mobility, carrier 

concentration, and carrier type — of the nanowires. This appears to be the only straightforward 

way to measure these properties for nanowires, 

for which conventional Hall measurements cannot 

be made. Single nanowire bridge structures were 

also fabricated.

Temperature dependence of MBE- and 

MOCVD-grown quantum dot density characterized — Determined the temperature dependence 

of the dot density for pulsed and continuously 

grown MBE samples as well as for MOCVD grown 

samples. Assuming an Arrhenius dependence of 

the dot density on temperature, both the activation 

energies (-1.61 and -1.64 eV) and the pre-exponentials (10-8 and 9x10-9 dots/um2

, for the pulsed and 

continuous-growth MBE samples, respectively) 

are nominally identical. For the MOCVD sample 

the dependence is quite different. The activation 

energy is lower (-3.63 eV) and the pre-exponential 

is smaller (10-22 dots/um2). The difference in fi t for 

the MBE and MOCVD dots is probably due to the 

fact that in MOCVD the adsorption and decomposition of the organometallics, as well as the diffusion and nucleation are controlled by the substrate 

temperature, while in MBE the fl ux is controlled 

independently and only the diffusion and nucleation 

depend on the substrate temperature. 

Uniformity of MBE- and MOCVD-grown 

quantum dots compared — Determined that MBE 

growth of InGaAs/GaAs quantum dots at low, 

continuous rates leads to uniformity in dot density 

equal to or better than that from MOCVD growth 

by collaborators. A nine by nine array of AFM 

images, taken over the central regions of 5.0 and 

7.5 cm diameter wafers, was analyzed to determine 

the distribution of dot heights and densities. For 

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MBE samples grown in a pulsed growth mode 

with a slow rotation rate the standard deviation 

in the dot density was typically 15–25 % of the 

average density. However, for samples with a 

continuous low growth rate and fast rotation rate, 

the standard deviation in the dot density was typically 3–4 % of the average. This is better than the 

10–15 % standard deviation in dot density found 

for most MOCVD samples. MBE-grown samples, 

both pulsed and continuously grown, have much 

narrower dot size distributions than their MOCVDgrown counterparts as shown in the histograms and 

AFM images below.

Histograms of the dot heights measured at 81 spots on wafers grown 

by a) MBE and b) MOCVD, showing the large range of heights for 

dots grown by MOCVD. AFM images from these same two wafers 

showing that the large height variations in dots grown by 

d) MOCVD occur on a local scale (the images are 3 x 3 μm2 and 

the color scale is 40 nm) consistently across the wafers.

AlGaAs composition standards offered — Delivered fi rst batch of NIST AlGaAs composition 

Standard Reference Material (SRM) number 

2841. This SRM consists of an epitaxial layer of 

AlxGa1-xAs with certifi ed mole fraction x of Al 

grown on a GaAs substrate. It is intended for use 

as a reference standard for analytical methods that 

measure the composition of thin fi lms, such as 

electron microprobe analysis (EMPA), photoluminescence (PL), Auger electron spectroscopy (AES) 

and X-ray photoelectron spectroscopy (XPS). The 

specifi ed Al mole fraction for each of these fi rst 

AlGaAs SRMs is near x = 0.2, with an expanded 

uncertainty of 0.0014 (k = 2 coverage). Also given 

in the SRM certifi cate is the uncertifi ed reference 

photoluminescence peak energy value. SRM 2842 

for nominal mole fraction x=0.3 is expected to be 

released soon. 

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40 Electronics and Electrical Engineering Laboratory

Standard reference material for mole fraction of Al in 

AlGaAs.

Source gas purity instrumentation calibrated

— Conducted tests of commercial cavity ring-down 

instrumentation in collaboration with the manufacturer and a semiconductor source gas manufacturer; 

the tests enabled calibration of the instrument for 

moisture in phosphine with record sensitivity at the 

sub-10-ppb level. When tested with arsine gas, this 

instrument was unable to provide useful moisture 

measurements because of spectral interference 

from arsine absorption lines. The manufacturer is 

pursuing the use of a different spectral region. 

KEY COLLABORATIONS

NIST Materials Science and Engineering Laboratory – TEM, cathodoluminescence, and electrical 

characterization of GaN nanowires

NASA Goddard Space Flight Center – development 

of GaN photodetectors for space applications

Matheson Tri-Gas – test of commercial instrumentation for measuring water as an impurity in 

semiconductor source gases

National Renewable Energy Laboratory, Golden, 

CO – analysis of cathodoluminescence and conductivity of GaN nanowires with scanning probe 

microscopy; test of fl exibility of nanowires; spatially dependent conductivity measurements of 

nanowires; coating nanowires with amorphous 

silicon to assist in p-n junction formation

University of Colorado – mechanical and optical 

measurements of nanostructures; atomic layer deposition coating of nanowires for surface reactivity 

modifi cations; biochemical sensors.

Sandia National Laboratory – study of MOCVD 

quantum dot uniformity

■

NIST Materials Science and Engineering Laboratory – Electron backscatter diffraction and convergent 

beam electron diffraction for measurement of strain 

in compound semiconductor nanostructures

RECENT PUBLICATIONS

J. B. Schlager, N. A. Sanford, K. A. Bertness, J. Barker, A. 

Roshko, P. Blanchard, “Polarization-resolved photoluminescence study of individual GaN nanowires grown by catalyst-free 

MBE,” Appl. Phys. Lett., Vol. 88, No. 21, pp. 213106-1–213106-

3 (2006).

A. Roshko, T. E. Harvey, S. Y. Lehman, R. Mirin, K. A. Bertness, B. Hyland, “GaAs buffer layer morphology and lateral 

distributions of InGaAs quantum dots,” J. Vacuum Sci. Technol, 

Vol. 23, No. 3, pp. 1226–1231 (2005).

K. A. Bertness, A. Roshko, N. A. Sanford, J. Barker, A. Davydov, “Spontaneously grown GaN and AlGaN nanowires,” J. 

Cryst. Growth, Vol. 287, No. 2, pp. 522–527 (2006).

K. A. Bertness, N. A. Sanford, J. Barker, J. B. Schlager, A. 

Roshko, A. Davydov, I. Levin, “Catalyst-free growth of GaN 

nanowires,” J. Electron. Mater., Vol. 35, No. 4, pp. 576–580 

(2006).

K. A. Bertness, C. M. Wang, M. L. Salit, G. C. Turk, T. A. Butler, A. J. Paul, L. H. Robins, “High-accuracy determination of 

epitaxial AlGaAs composition with inductively coupled plasma 

optical emission spectroscopy,” J. Vacuum Sci. Technol. B, Vol. 

24, No. 2, pp. 762–767 (2006).

K. A. Bertness, A. Roshko, S. E. Asher, C. L. Perkins, “Storage conditions for high-accuracy composition standards of 

AlGaAs,” J. Vacuum Sci. Technol. B, Vol. 23, No. 3, pp. 

1267–1271 (2005).

S. Y. Lehman, K. A. Bertness, J. T. Hodges, “Optimal spectral 

region for real-time monitoring of sub-ppm levels of water in 

phosphine using cavity ring-down spectroscopy,” Journal of 

Crystal Growth, Vol. 261, pp. 225–230 (2004).
Optoelectronics Division 41

APPENDIX A: MAJOR LABORATORY FACILITIES

SEMICONDUCTOR GROWTH AND OPTOELECTRONIC DEVICE FABRICATION

The Division makes use of a gas-source molecular-beam epitaxy system and associated in situ 

and ex situ measurement equipment for III-V semiconductor growth and characterization. It 

also maintains a cleanroom facility for thin-fi lm deposition, photolithography, and wet and 

dry etching. The facilities support the activities described above, particularly for the Optical 

Materials Metrology, Nanostructure Fabrication and Metrology, and Semiconductor Growth 

and Devices Projects.

LASER POWER/ENERGY DETECTOR CALIBRATION SYSTEMS

The Optoelectronics Division has established and maintains several state-of-the-art measurement 

systems for calibrating most types of laser power and energy detectors. These measurement 

systems incorporate unique, specially designed, electrically calibrated laser calorimeters that 

are used as primary standards. The calorimeters are used in conjunction with beamsplitter-based 

optical systems to provide measurement services for laser power and energy that cover a wide 

range of powers, energies, and wavelengths for detectors used with both cw and pulsed lasers. 

This assembly of laser power and energy detector calibration systems represents the best overall 

capability of this kind in the world. In many cases (e.g., excimer laser measurements at 248 nm, 

193 nm, and 157 nm), the Division has the only measurement capability in the world.
42 Electronics and Electrical Engineering Laboratory

APPENDIX B: NRC POST-DOC AND OTHER

RESEARCH OPPORTUNITIES

PROFESSIONAL RESEARCH EXPERIENCE PROGRAM (PREP)

The Professional Research Experience Program (PREP) is designed to provide valuable laboratory experience to undergraduate and graduate students from both the University of Colorado 

at Boulder and the Colorado School of Mines at Golden, and to recent Ph.D. recipients from 

these and other universities. Students and postdocs are employed by the University of Colorado or the Colorado School of Mines and normally carry out research at the NIST Boulder 

Laboratories.

Students are usually hired just before the spring, fall, or summer terms, and may be employed 

for one or more terms. Postdocs may begin any time during the year. Applications are accepted 

throughout the year.

NIST pays in-state tuition for PREP undergraduate students during the fall and spring semesters and an hourly wage. Graduate students receive in-state tuition and a stipend. Postdocs 

receive a stipend.

Eligibility requirements include U.S. citizenship or permanent residency and, for students, a 

minimum 3.0 GPA (grade point average).

Information is available at http://www.boulder.nist.gov/div815/ResearchOpps/resopps.htm

SUMMER UNDERGRADUATE RESEARCH FELLOWSHIPS (SURF)

The SURF NIST Boulder Program provides 12-week appointments for outstanding undergraduates to engage in state-of-the-art research with senior scientists and engineers in the unique 

research facilities at the NIST campus in Boulder, Colorado.

Eligibility requirements include U.S. citizenship or permanent residency, and undergraduate 

status at a U.S. university or college with a technical major. A G.P.A. of 3.0/4.0 or better is 

recommended. Applicants must be covered by a health insurance plan (either through school 

or family). Students with majors in physics, materials science, chemistry, mathematics, computer science, or engineering are encouraged to apply. There may be research opportunities 

for students with other majors.

The program duration is May to August, with adjustments to be made to accommodate specifi c 

academic schedules (e.g., quarter systems). 

Application deadline is February 15. The student’s university must submit a grant proposal 

that provides details about its academic programs and nominates one or more students. Each 

student must provide a transcript, two letters of recommendation, and a personal statement of 

interest.

Housing will be provided within easy walking distance of NIST.

Further information is available at http://SURF.Boulder.NIST.gov.

NATIONAL RESEARCH COUNCIL ASSOCIATESHIP OPPORTUNITIES

The National Institute of Standards and Technology (NIST), in cooperation with the National 

Research Council (NRC), offers awards for post-doctoral research in many fi elds. These awards 

provide a select group of scientists and engineers an opportunity for research in many of the 
Optoelectronics Division 43

areas that are of deep concern to the scientifi c and technological community of the nation. NIST, 

with direct responsibilities for the nation’s measurement network, involves its laboratories in 

the most modern developments in the physical, engineering, and mathematical sciences and 

the technological development that proceed from them. The Research Council, through its 

Associateship Programs offi ce, conducts an annual national competition to recommend and 

make awards to outstanding scientists and engineers at the postdoctoral level for tenure as guest 

researchers at participating laboratories. The deadline for applications each year is February 1 

for appointments beginning between July to December, and August 1 for appointments beginning January through June.

THE OBJECTIVES OF THE PROGRAMS ARE:

To provide postdoctoral scientists and engineers of unusual promise and ability opportunities for research on problems, largely of their own choosing, that are compatible with the 

interest of the sponsoring laboratories.

To contribute thereby to the overall efforts of the federal laboratories. Eligibility requirements include U.S. citizenship and receipt of Ph.D. within fi ve years of application. NRC 

positions involve a two-year tenure at NIST.

For more detailed information, including instructions for applicants, please contact the 

Optoelectronics Division Offi ce and request a copy of the NRC Postdoctoral Opportunities 

booklet. You also may visit the Optoelectronics Division web page (http://www.boulder.

nist.gov/div815); or the NRC Research Associateship Program web page (http://www.national-academies.org/rap, or for a description of the NIST NRC program, see http://nrc58.

nas.edu/pgasurvey/data/aobooks/rapbooks.asp?mode=frntmtr&frntmtrid=43)

OPPORTUNITIES FOR THE YEAR 2007 WITH THE OPTOELECTRONICS DIVISION

THROUGH THE NRC RESEARCH ASSOCIATESHIP PROGRAM

QUANTUM DOT MORPHOLOGY

Advisor: A. Roshko 

Quantum dots have attracted a great deal of interest because of their unique properties and 

possibilities for optoelectronic applications. However, control of dot density, composition, position, size, and shape remain major obstacles for many device applications. We invite proposals 

to address these issues through an investigation of quantum dot morphology as a function of 

growth parameters such as temperature, rate, thickness, composition, and dot stacking. Studies 

of the interrelations between these variables and strain state are also of interest. State-of-the-art 

molecular beam epitaxy with refl ected high-energy electron diffraction, atomic force microscopy, high-resolution X-ray diffraction, and transmission electron microscopy are available for 

analyzing quantum dot distributions, heights, shapes, spacings, and strain fi elds. Correlation 

with optical properties, such as photoluminescence, is also of interest. The work will contribute 

to a more complete understanding of quantum dot morphology, how it correlates with device 

performance, and how it can be controlled through the choice of growth conditions.

MOLECULAR SPECTROSCOPY USING RING-DOWN CAVITIES AND ITS APPLICATION TO

SEMICONDUCTOR CRYSTAL GROWTH

Advisor: K. A. Bertness 

Gases such as phosphine, ammonia, arsine, nitrogen, silane, and germane are widely used in 

semiconductor synthesis and processing. Most of these processes are highly sensitive to contamination, although the precise incorporation mechanisms and concentrations of concern are 

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44 Electronics and Electrical Engineering Laboratory

poorly known. We have developed cavity ring-down spectroscopy as a tool for high-sensitivity 

measurements of impurities in gases along with the capability of using many of these gases in 

gas-source molecular beam epitaxy growth. The system has a sensitivity for measuring water as 

an impurity down to approximately 30 ppb in phosphine and 10 ppb in nitrogen using laser light 

near 935 nm. We anticipate the availability of new laser sources in the next few years that will 

signifi cantly enhance the fl exibility and sensitivity of the instrument. Because of its fast time 

response, cavity ring-down spectroscopy is also useful for measuring time-dependent effects 

and confi rming the effi cacy of purifi ers. We invite proposals extending the capability of the 

instrument to new impurities or host gases (e.g., novel studies of correlations of gas properties 

with semiconductor crystal properties and fundamental studies of the impurity incorporation 

process).

PHOTONIC CRYSTALS

Advisor: R. Mirin 

Photonic crystals are meta-materials whose optical properties are determined by the photonic 

band structure that arises from resonant photon scattering off the nanometer-scale physical 

structure, in direct analogy with well-established concepts of electronic bands in semiconductors. Photonic crystals offer the new possibility of creating materials with custom-tailored 

bandgaps and dispersion curves, liberating light-emitting devices from the constraints caused 

by the underlying material dispersion. We are pursuing an active program of photonic crystal 

dispersion engineering with the aim of vastly enhancing the performance of semiconductor 

light emitters. Specifi cally, we are designing, fabricating, and measuring photonic crystal 

nanocavities for Purcell-enhanced single-photon sources, circular Bragg gratings for enhanced 

light extraction in LEDs, chirped waveguide gratings for dispersion control in semiconductor 

mode-locked lasers, and waveguide arrays for nonlinear soliton formation. Our capabilities 

include electromagnetic modeling, nanofabrication, quantum-optical measurements and ultrafast measurements.

SEMICONDUCTOR QUANTUM OPTICS

Advisor: R. Mirin 

We are developing a regulated source of single photons by fabricating a single photon turnstile with a single quantum dot. Our goals include spontaneous emission control and delivery 

of the individual photons to any other on-chip location through photonic crystal waveguides. 

Important technologies for this project include microcavities, microdisks, photonic crystals, 

and nonlinear optics. We invite experimental and/or theoretical proposals that can complement and expand on this ongoing effort. Available resources include epitaxial semiconductor 

growth, e-beam lithography, fabrication facilities, and fi nite-difference time-domain software 

for electromagnetic modeling.

OPTICAL SPECTROSCOPY OF QUANTUM DOTS

Advisor: R. Mirin 

Self-assembled semiconductor quantum dots have been demonstrated for many optoelectronic 

devices (lasers, optical amplifi ers, and photodetectors) and proposed for novel applications 

such as quantum computing. However, there is still a lack of fundamental knowledge about 

the optical and electronic properties of these quantum dots, such as homogeneous linewidth, 

oscillator strength, coupling, and carrier escape mechanisms, especially at the single quantum 

dot level. We invite proposals that will investigate these or other fundamental characteristics 

of self-assembled quantum dots.
Optoelectronics Division 45

COHERENT SPECTROSCOPY OF QUANTUM DOTS

Advisor: R. Mirin 

We are currently performing high-resolution optical spectroscopy on self-assembled semiconductor quantum dots. Our technique employs narrow linewidth tunable lasers and heterodyne 

detection. Recent results from our group have shown that these structures are almost purely 

radiatively broadened at 9 K. We are soliciting proposals to extend this experimental method to 

investigate multi-exciton and charged exciton complexes. We are interested in the fundamental 

properties of these transitions as well as the coherence in these coupled-state systems. Optical 

phenomena such as electromagnetic-induced transparency (EIT) should be observable.

MBE GROWTH OF QUANTUM DOTS

Advisor: R. Mirin 

We are developing single photon sources based on epitaxially grown single quantum dots. 

Many quantum dots are deposited during growth and individual dots are isolated by masking 

and etching. The goal of this project is to use novel methods of controlling the exact placement 

and size of the quantum dots. This will enable schemes of coupling two or more quantum dots 

for applications in quantum information and quantum optics.

ENGINEERED QUANTUM STATES OF LIGHT

Advisors: R. Miri, T. Clement

We are investigating methods of creating new quantum states of light such as Schrodinger cat 

states, NOON states, and Fock states. These new states have a variety of applications, including linear optical quantum computing, quantum metrology (for example, Heisenberg limited 

interferometry), and fundamental physics (loophole-free Bell measurements). We are particularly interested in utilizing our high quantum effi ciency photon number resolving detectors to 

enable creation of these states. Our group includes both experimentalists and theorists. We 

invite proposals to further develop and utilize quantum states of light.

NANOSCOPIC WIDE-BANDGAP MATERIALS CHARACTERIZATION BY CW AND ULTRAFAST

NONLINEAR OPTICS

Advisors: N. A. Sanford, J. B. Schlager 

Near-fi eld and confocal microscopies provide unique methods of characterizing a wide variety 

of semiconductor, dielectric, and hybrid optoelectronic materials and interfaces. We are developing methods of nanoscopic multiphoton spectroscopy and nonlinear optics for examining 

local structural and electronic properties of the wide-bandgap III-nitride alloy semiconductors. 

The techniques include ultraviolet (UV) second-harmonic generation in addition to cw and 

time-resolved, multiphoton UV spectroscopy that employ NSOM and confocal techniques. 

We are particularly interested in the study of local defects, polytyping, inversion domains, 

and alloy segregation; spectroscopy on the scale of defect separation (roughly 100 nm); and 

ultrafast processes involving interactions with strong static polarization fi elds in these materials. The spectroscopic results are correlated with X-ray diffraction imaging, high-resolution 

cathodoluminescence, and TEM.

METROLOGY AND PROTOTYPING OF WIDE-BANDGAP SEMICONDUCTOR QUANTUM

NANOWIRE STRUCTURES AND DEVICES

Advisors: N. A. Sanford, K. A. Bertness, A. Roshko

Semiconductor quantum nanowires offer new applications in areas such as chemical sensors, 

NEMs, nanolasers, and nanoscale thermoelectric devices. A key aspect of these structures that 
46 Electronics and Electrical Engineering Laboratory

makes the research challenging and enables the utility of various nanowire devices is that many 

physical phenomena do not scale from the macro to nano regimes. Our research primarily focuses 

on nanowires grown from wide-bandgap semiconductors including the group III-nitride (GaN, 

AlN, InN) and ZnO material systems. We are interested in nanowire growth techniques that 

include MBE, vapor transport, and catalyst methods. We are interested in a range of research 

topics, from the applied to the fundamental, covering such areas as understanding the evolution 

of the microstructure of nitride semiconductors; development of nanotemplates for patterned 

growth of nanowires; optimization of p-type doping in nanostructures; developing methods of 

making electrical contact to single nanowires or arrays of nanowires; and development of new 

measurement methods for quantifying nanoscale piezoelectric, transport, and optoelectronic 

phenomena. Current device interests include nanowire lasers, LEDs, photodetectors (primarily 

in the UV), UV and visible light emitters (i.e., for solid state lighting and water purifi cation), 

and fi eld emitting ion sources for mass spectrometry. We are also working on the design and 

fabrication of prototype nanowire electronic devices such as FETs. We welcome proposals aimed 

at new technological aspects of semiconductor quantum nanowire research and application. 

Our characterization resources include triple-axis X-ray diffraction, atomic force microscopy, 

scanning electron microscopy, ultrafast nonlinear optical characterization, near-fi eld scanning 

optical microscopy, cw and time-resolved photoluminescence, device processing, and electrical 

measurements. Opportunities exist for collaborative work within NIST for more specialized 

characterization such as TEM, fi eld-emission SEM, STM, cathodoluminescence, nanoscale 

electrical and thermal measurements.

Our existing programs use gas-source molecular beam epitaxy growth of nitrides, phosphides, 

and arsenides with a focus on nanostructures. Other in-house collaboration includes vapor phase 

and catalyst growth methods for nanowire growth. Also, a wide range of clean room processing 

equipment is available in order to carry out prototyping of specialized nanostructures.

IN-SITU METROLOGY OF EPITAXIAL CRYSTAL GROWTH FOR SEMICONDUCTOR

OPTOELECTRONICS

Advisors: K. A. Bertness, R. K. Hickernell

Semiconductor optoelectronic devices are being employed in a variety of applications, including telecommunications, computer interconnects, data storage, display, printing, and sensor 

systems. Most of these devices rely on accurate, reproducible epitaxial crystal growth; however, further reductions in growth cost will require further development of in situ and ex situ 

measurement tools. Our research focuses on optical in situ material probes (i.e., pyrometry, 

atomic absorption spectroscopy, and broadband normal-incidence optical refl ectance) correlated 

with refl ectance high-energy electron diffraction, ex situ X-ray diffractometry, photoluminescence spectroscopy, optical refl ectance, and extensive modeling capabilities. Other resources 

include in-situ mass spectrometry, atomic force microscopy, transmission electron microscopy, 

electrochemical profi ling, and clean room facilities for processing test and device structures. 

We have recently demonstrated growth of GaN nanowires, and proposals specifi c to plasma 

nitrogen characterization and monitoring of rough surfaces are encouraged. We also examine 

the practical utility of various measurement tools through the growth of device structures, with 

emphasis placed on vertical-cavity surface-emitting lasers, in-plane lasers, quantum dot lasers, 

and saturable Bragg absorbers.
Optoelectronics Division 47

SUPERCONDUCTING AND NANOMETER-SCALE DEVICES FOR INFRARED TO MILLIMETERWAVE APPLICATIONS

Advisor: E. Grossman 

Our goal is to explore the physical mechanisms and limitations of devices operating in the frequency range from 0.1 to 100 THz, and to develop novel devices and measurement techniques. 

For the short wavelength end, we use electron-beam lithography to fabricate the submicron 

structures required to minimize parasitic impedances. One specifi c research area includes mixers and harmonic mixers for frequency synthesis and high-resolution spectroscopy; another 

research area involves IR to millimeter-wave imaging radiometry. Our main focus is on highsensitivity bolometers and superconducting multiplexers based on SQUIDS. Other devices of 

interest include high-Tc superconducting bolometers; room-temperature, thin-fi lm bolometers; 

lithographic and/or micromachined coupling structures, particularly antennas and integrating 

cavities; superconducting mixers/rectifi ers; and room-temperature mixers/rectifi ers (e.g., lithographic metal-insulator-metal diodes).

FLAT PANEL DISPLAY METROLOGY

Advisors: E. F. Kelley (Boulder), P. A. Boynton (Gaithersburg) 

NIST’s fl at panel display laboratory serves the display industry by developing and quantifying 

good electronic display metrology for industrial use. With the explosion of the information age, 

the Internet, and e-commerce, the use of fl at panel displays has become a growing need for US 

industries. Good display measurement methods are needed for several reasons: (1) specifi cation 

language needs to rest solidly upon good metrology, (2) fi erce competition between technologies requires good metrology to distinguish desirable features, and (3) users and implementers 

of displays need accurate characterizations of displays for selection purposes. NIST is doing 

research in (1) equipment on improving measurements made on displays; (2) development of 

display metrology with various standards organizations; (3) development of display metrology assessment methods and equipment to provide guidance for the implementation of good 

measurement methods in the display industry; and (4) display refl ectance characterization, 

measurements, and modeling based on the bi-directional refl ectance distribution function. Opportunities are available at both Boulder and Gaithersburg campuses.

HIGH SPEED OPTOELECTRONICS MEASUREMENTS

Advisors: P. D. Hale, D. F. Williams

Increasing data rates and bandwidths of optical telecommunications, cable television systems, 

remote microwave antenna links, and computer data interconnections all require advanced techniques for accurately determining optical transmitter and receiver frequency response in both 

magnitude and phase. Methods being investigated at NIST include heterodyne and ultrashort 

pulse technologies. Current research focuses on fully calibratable measurement of frequency 

response with low uncertainty to 110 GHz and extension to 400 GHz in the near future. We are 

especially interested in the measurement of response phase with low uncertainty using high-speed 

sampling techniques and in methods for verifying these measurements in a coaxial or on-wafer 

environment. Future calibration artifacts will require fabrication of ultrafast photodetectors. We 

are also interested in theoretical studies of the modulation characteristics, frequency response, 

spectral response, saturation, and electrical characteristics of optical receivers that would further 

enhance our metrology effort.
48 Electronics and Electrical Engineering Laboratory

HIGH-SPEED OPTICAL RECEIVERS AND OPTOELECTRONIC INTEGRATED CIRCUITS

Advisors: P. D. Hale, R. Mirin, D. F. Williams

The need for ever smaller size and increased bandwidth of optoelectronic devices is requiring these devices to be packaged in hybrid modules and optoelectronic integrated circuits. 

Characterization of the frequency response and electrical properties of these devices requires 

a change in measurement strategy away from coaxially connected modular devices to on-wafer 

measurements. We are developing a new fully calibratable on-wafer measurement paradigm 

for calibrating optoelectronic and electronic devices to bandwidths exceeding 110 GHz. We 

are interested in fabricating new high-speed receivers that will be used as calibration artifacts 

in this new measurement strategy. Possible designs might include metal-semiconductor-metal 

photoconductive switches or p-i-n photodiodes grown in low-temperature GaAs or InGaAs. The 

work will result in artifacts that will be used to calibrate high-speed measurement equipment.

OPTICAL PULSE CHARACTERIZATION AND SYSTEM MONITORING

Advisors: P. D. Hale, K. B. Rochford, C. M. Wang , K. A. Remley, D. F. Williams

Optical component measurements alone will not be adequate to design and operate the next 

generation of optical communications, which will include dynamic channel add/drop switching, routing, gain control, equalization, and dispersion compensation. Accurate methods to 

dynamically characterize system impairment via thorough measurements of optical signal 

amplitude, phase, jitter, and noise are needed. We are soliciting proposals for methods that will 

assess system impairment, particularly methods that will discriminate between failure modes 

and offer insight into the strengths and weaknesses of various modulation, error correction, and 

dispersion compensation schemes.

CHARACTERIZATION OF DISPERSION COMPENSATION AND EQUALIZATION SCHEMES

Advisors: P. D. Hale, K. B. Rochford, C. M. Wang , K. A. Remley, D. F. Williams

Various optical and electrical methods of dispersion compensation and gain equalization are 

now being employed to extend the length of short- and long-reach optical communications 

systems. Electrical impairments known as frequency dependent loss and multipath interference 

also appear in board-level electrical interconnects, wireless communications, and data storage. 

Although the impairments appear in systems that differ greatly and can affect vastly different 

time scales, they can be addressed through similar techniques of equalization and fi ltering. We 

are soliciting methods for characterizing equalization and dispersion compensation methods, 

and particularly their effi cacy for correcting low probability impairments.

WAVEFORM METROLOGY

Advisor: P. D. Hale 

Current techniques used by industry for characterizing digital waveforms, both electrical and 

optical, are qualitative at best. As a result, the specifi cations for test equipment and communication systems are conservative and are not well understood. For example, the computer and 

communications industries both need measurements of different types of jitter and inter-symbol 

interference because these effects could cause erroneous bit transmission. We have developed 

a world-class capability for characterizing and calibrating equipment used in the acquisition of 

high-speed waveforms. We are looking for proposals that will investigate calibrated waveform 

measurement and the quantitative study of waveform metrics that characterize parameters such 

as random jitter, inter-symbol interference, and eye margin.
Optoelectronics Division 49

TUNABLE LASER ENSEMBLE DEVELOPMENT FOR LASER RADIOMETRY

Advisor: J. H. Lehman 

The calibration of laser and optical fi ber meters over wavelengths ranging from 200 nm to 

1800 nm requires laser sources that are stable, broadly tunable, and have well defi ned optical 

properties (e.g., polarization, beam quality). Our goal is to go beyond merely demonstrating 

what wavelengths may be produced by novel methods. We will demonstrate a variety of sources 

that are continuously tunable over the entire wavelength of interest (200 nm to 1800 nm) and 

deliver the output of these sources to various laboratories using optical fi ber. This will enable 

cost-effi cient, routine, calibration services having low uncertainties. We may employ new 

methods and equipment or optimize existing methods and equipment to ensure that NIST can 

provide laser power measurement comparisons to standards laboratories around the world as 

well as to manufacturers of laser and optical fi ber power measurement equipment. Several new 

projects are currently under consideration to provide novel, robust methods for the generation 

and transportation of tunable laser light.

CARBON NANOTUBE COATINGS FOR LASER POWER AND ENERGY MEASUREMENTS

Several areas of research are currently being pursued: improved coatings for thermal detectors, ultraviolet detectors resistant to damage and aging, and improved transfer standards for 

pulsed-laser radiation measurements. In each case, our goal is to develop and maintain optical 

detectors that are traceable to electrical standards for the purpose of maintaining calibration 

services in the area of laser power and energy measurements. Nearly all of the primary standards for laser power and energy measurements at NIST are based on thermal detectors. Our 

goal is to establish carbon nanotube coatings as a practical choice for the next generation of 

standards. We also employ a variety of photodiode-based detectors as transfer standards for 

routine laser power calibrations for our customers. In each of these areas, the practical matters 

of providing cost-effi cient, routine calibrations having low uncertainties must be considered. 

Topics of interest include new technologies and/or methods for developing and transferring 

detector-calibration information from one area to another.

ULTRAVIOLET LASER METROLOGY

Advisors: J. Lehman, M. L. Dowell 

In recent years, ultraviolet (UV) laser — specifi cally diode lasers — have found increased use 

in a variety of industrial, commercial, homeland security, and medical applications. For example 

applications range from high-defi nition digital video to detection of chemical and biological 

aerosols. Currently there is no primary standard for calibration of high-power continuous laser 

power meters. Aging and hardening of materials exposed to UV laser radiation are among the 

challenges to developing new measurement tools. Currently we are pursuing carbon nanotube 

based coatings for thermal detectors as well as optoelectronic means of creating artifi cial spectra 

for calibration of chemical, biological, and explosive sensors. Our work includes the development 

of high-accuracy UV primary and transfer standard detectors, beam profi le characterization, 

laser power, energy, and dose measurement services.
50 Electronics and Electrical Engineering Laboratory

INFRARED FREQUENCY COMB DEVELOPMENT AND APPLICATION

Advisor: N. R. Newbury 

A supercontinuum of light that spans over an octave in frequency can be generated by launching pulses from femtosecond fi ber lasers into highly nonlinear optical fi ber. Through recently 

developed techniques, this supercontinuum can be phase-locked to a reference and thereby 

provide a stable frequency comb with a spacing equal to that of the laser repetition rate. These 

frequency combs have the potential to revolutionize optical frequency metrology in the telecommunication band since optical frequencies can now easily be measured relative to the time 

standard. We invite proposals that explore the generation, properties, and applications of infrared 

frequency combs. We are particularly interested in the generation of stable frequency combs in 

the telecommunications band using either femtosecond fi ber lasers or other laser technology 

that could be used for wavelength metrology. Other examples of proposals include developing 

a better understanding of the noise properties of the frequency comb, and exploring other uses 

of the frequency comb related to LADAR or optical coherence tomography applications.
Optoelectronics Division 51

APPENDIX C: CONFERENCES AND WORKSHOPS

LASER MEASUREMENTS SHORT COURSE

The Optoelectronics Division offers an annual short course on laser measurements. The 31⁄2-day 

course emphasizes the concepts, techniques, and apparatus used in measuring laser parameters. 

A tour of the NIST laser measurement laboratories is included. The most comprehensive seminar 

of its type, this course is ideal for those who need to understand the characteristics of lasers 

and laser measurements or who are responsible for laser systems. The seminar is taught by 

laser experts from NIST, industry, and other government agencies, and is intended to meet the 

needs of metrologists, scientists, engineers, laboratory technicians, educators, managers, and 

planners involved in the use of laser systems. A degree in physics or engineering or equivalent 

experience is assumed, and some experience in the use of lasers is desired. 

The Technical Program covers a wide range of topics, such as:

Optics for Laser Measurements

Lenses, spherical aberration, diffraction, laser beams, beam divergence, beamsplitters, 

detector linearity.

Attenuation Techniques

Filters, specular refl ectors, diffuse refl ectors, speckle statistics.

Basic Laser Power/Energy Standards

Calorimeter theory and design, data methods, volume absorbers, source standards, absolute 

quantum detectors.

Laser Power/Energy Measurement Techniques

Calorimetry, beamsplitter system, calibration system, power/energy measurements, documentation, automation.

Pulse Measurements

Pulse parameter defi nitions, energy measurements, waveform measurements, detector 

characterization, time-domain techniques, subnanosecond measurements, calibrations.

Optical Fiber Power Measurements

Traceability, calibration system, measurement uncertainty, detector linearity, detector uniformity, tunable lasers, round robins, connector effects, international comparisons.

Diode Lasers

Temperature stability, frequency control, measurement of peak power and energy, beam 

focusing, beam uniformity, angular divergence.

Statistics and Error Analysis

Errors, uncertainties, measurement process characterization, estimation, statistical control.

Laser Safety

Hazards to the eye, evaluation measurements, beam diagnostics for safety purposes, eye 

protectors.

The Laser Measurements Short Course is typically held the fi rst week in August. Interested 

parties should consult the Optoelectronics Division Offi ce or visit the Division Web page at 

http://www.boulder.nist.gov/div815/ for information about upcoming courses. 

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52 Electronics and Electrical Engineering Laboratory

DISPLAY METROLOGY SHORT COURSE

The National Institute of Standards and Technology offers a short course on display metrology 

in Boulder, Colorado, several times during the year. The three-day course consists of a one-day 

lecture and two days of hands-on measurements, diagnostics, and experiments. Current short 

course dates and a description of course contents can be found at www.fpdl.nist.gov/DMSC.

html

Lecture topics include: 

Review of radiometry, photometry, and colorimetry

Discussion of quantities and units used in photometry

Review of simple photometric calculations

Review of types of measurement instrumentation

Veiling glare and management of stray light

Use of fl at masks and frusta

Display refl ection characterization

Refl ection haze and robustness

Bidirectional refl ectance distribution function

Projection measurements

Diagnostics

Measurement uncertainty

Laboratory redundancy

Review of refl ection measurements in some standards, e.g.,

– SAE J1757 (ISO 15008), ISO 13406 & 9241, and others

Laboratory demonstrations include:

Refl ection robustness (common confi gurations)

Projection measurements

Refl ection measurements

Characterization of white refl ectance standard

Characterization of black glass

BRDF measurements (low- and high-resolution)

Diffuse refl ection measurements

Colors and gamut measurements with detector diagnostics

Comparison of various color measurement instrument technologies

Use of masks and frusta

Small-area contrast measurements

Properties of array cameras (e.g., CCD cameras)

Considerations for uniform sources

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Optoelectronics Division 53

APPENDIX D: CALIBRATION SERVICES

From optical lithography for semiconductor manufacturing to the micromachining of small 

structures such as ink jet printer nozzles, lasers are fi nding their way into an increasingly diverse 

number of industrial applications. As this expansion continues, laser metrology will continue to 

become more important for improved in-line process control, increased yields, and laser safety. 

In support of these applications, the Optoelectronics Division provides calibrations services 

at laser power levels from nanowatts to kilowatts, and pulse energy levels from femtojoules 

to megajoules. Wavelength ranges include the standard ultraviolet, visible, and near infrared 

laser lines. In addition to standard laser lines, we have a tunable laser ensemble that can provide measurements of additional laser wavelengths upon request. Detailed information for the 

division’s calibration service capabilities is given in Tables 1 through 6. Other laser-related 

measurement services are available upon request and will be delivered at cost.

Table 1. Laser power and energy calibration services for optoelectronic devices used with cw laser radiation.

Laser Wavelength Power

HeCd 325 nm 1 nW − 50 mW

Argon

488 nm 1 nW − 6 W

514 nm 1 nW − 10 W

Other Argon wavelengths available, call for power levels.

HeNe 633 nm 1 nW − 20 mW

Diode 375, 672, 830, 850, 1310, and 1550 nm 1 nW − 20 mW

Nd:YAG

1064 nm 1 nW −1 kW (6 kW off-site)

1319 nm 1 μW − 50 mW

Erbium 1523 nm 1 μW − 30 mW

CO2 10.6 μm 100 W − 2 kW (6 kW off-site)

Ti:Sapphire 700 nm – 1 μm 1 nW −1 W

Additional dye laser wavelengths available, call for power levels

Table 2. Laser power and energy calibration services for optoelectronic devices used with pulsed-laser radiation.

Laser Wavelength Energy

Q-Switched

Nd:YAG 1.06 μm

1−300 mJ/pulse (1 – 20 Hz)

1 mW to 6 W average

Low Level

Nd:YAG 1.06 μm

10-4−10-8 W (peak)

10-11−10-15 J/pulse

KrF 248 nm 5 μJ/Pulse – 250 mJ/Pulse

50 μW – 7 W average

ArF 193 nm 5 μJ/Pulse – 5 mJ/Pulse

10 μW – 3 W average

F2 157 nm 1 μJ/Pulse – 3 mJ/Pulse

1 μW – 1 W average
54 Electronics and Electrical Engineering Laboratory

Table 3. Detector characterization services.

Parameter Wavelength Range Status

Optical Detector 

Spatial Uniformity 635, 850, 1300, and 1550 nm Detector size: 1 mm – 17 cmResolution: 0.1 mm

Special 

Test

Optical Detector 

Linearity

193, 248, and 1064 nm

10.6 μm 1 nJ/pulse – 10 mJ/pulse Special Test

Table 5. Temporal and frequency response measurements of optical detectors and receivers.

Table 4. Optical fi ber power meter measurement services.

Parameter Wavelength (nm) Range Status

Absolute Power Calibration

670, 780, 850, 980

1310, 1550 10 – 100 μW Calibration Service

980 1 – 200 mW Special Test

1480 1 μW – 1 W Special Test

Optical Fiber Power Meter 

Linearity 850, 1310, 1550 60 – 90 dB Calibration Service

Optical Fiber Power Meter 

Spectral Responsivity 450 – 1750 < 2 % uncertainty Calibration Service

 

 

Parameter Wavelength Range Status

Optical Receiver Frequency 

Response (Magnitude)

1319 nm 300 kHz – 

50 GHz Special Test

1550 nm 1 MHz – 50 GHz Special Test

Optical Receiver Vector 

Frequency Response 1550 nm 200 MHz – 110 GHz Special Test

Reference Receiver (Optical 

Oscilloscope) Vector Frequency 

Response

850 nm

1550 nm

100 fs impulse 

source Special Test

Optical Modulation Response 

Transfer Standard 1319, 1550 nm 300 kHz –110 GHz Special Test
Optoelectronics Division 55

Table 6. Temporal and frequency response measurements of electrical signal generators and oscilloscopes.

Parameter Connector 

type Range Status

Impulse spectrum magnitude 

and phase

2.4 mm 10 MHz – 50 GHz Special Test

1.0 mm 200 MHz – 

110 GHz Special Test

Oscilloscope vector frequency 

response

2.4 mm 200 MHz – 

110 GHz Special Test

Oscilloscope vector frequency

response with time-domain analysis 1.0 mm 200 MHz – 110 GHz Special Test

Pulse generator pulse waveform 

parameters: 

Transition duration

Amplitude

3.5 mm

1.0 mm

~10 ps – ~100 ps

< ~400 mV

5 ns epoch

Special Test

See http://www.boulder.nist.gov/div815/Calibrations/Calibrations.htm for more information.

For technical information contact:

Marla L. Dowell, Group Leader

Sources, Detectors, and Displays Group

NIST 815.01

325 Broadway

Boulder, CO 80305

TEL: 303-497-7455

e-mail: marla.dowell@boulder.nist.gov

For scheduling and shipping information contact:

John Lomax, 

Measurement Services Coordinator

Optoelectronics Division

NIST 815.00

325 Broadway, 1-3055

Boulder, CO 80305

TEL: 303-497-3842

FAX: 303-497-4286

e-mail: jlomax@boulder.nist.gov
56 Electronics and Electrical Engineering Laboratory

PRIMARY STANDARDS FOR LASER RADIOMETRY

A SiC absorbing cavity for the 157 nm excimer laser 

calorimeter. Developed over the past few years, we 

now provide power and energy calibrations at this 

wavelength to support the semiconductor photolithography industry.

The Laser-Optimized Cryogenic Radiometer, developed in the late 1990s, and used for the highest accuracy measurements with low-level cw lasers, 100 μW 

to 1 mW at wavelengths from 0.4 μm to 2 μm.

The C-Series Calorimeter, originally developed in the 

1970s for use with cw lasers in the range from 50 μW 

to 1 W and 0.4 μm to 2 μm wavelength. Improved versions are in current use for calibrations.

The K-Series Calorimeter, developed in the 1970s, 

for high-power cw lasers in the range from 1 W to 

1000 W and wavelengths from 0.4 μm to 20 μm. This 

calorimeter is in current use for calibrations.

Three versions of this standard are used for pulsedlaser calibrations. The Q-Series, developed in the 

1980s, is used for 1.06 μm lasers. The QUV and 

QDUV calorimeters, developed in the 1990s, are in 

current use for calibrations at 248 nm and 193 nm, 

respectively.

The BB Calorimeter, developed around 1980 for the 

U.S. Air Force Metrology Laboratory, and is in current use for cw lasers with power levels up to 100 kW.
Optoelectronics Division 57

APPENDIX E: STANDARD REFERENCE MATERIALS 

SRM 

Number Name Brief Description

Composition Standards

2841 Composition Standards 

for Compound 

Semiconductors

Standards of epitaxial layers of compound semiconductors for application in calibration of analytical equipment 

(SIMS, EMPA, AES, XPS, etc.) and photoluminescence 

mapping. The SRM 2841 is specimens of epitaxial layers 

of AlxGa1-xAs grown on GaAs substrates with x near 0.20 

and uncertainty of ± 0.002. Additional mole fractions are 

also under development.

Wavelength Calibration Standards

2514 Wavelength Calibration 

Reference for 1560-1595 

nm – Carbon Monoxide 

(

12C16O)

Fiber-coupled molecular gas absorption cell with absorption lines in the WDM L-band between 1560 nm and 

1595 nm. The center wavelengths of the absorption lines 

are certifi ed with expanded uncertainties ranging from 

0.4 pm to 0.7 pm.

2515 Wavelength Calibration 

Reference for 1595-1630 

nm – Carbon Monoxide 

(

13C16O)

Fiber-coupled molecular gas absorption cell with absorption lines in the WDM L-band between 1595 nm and 

1630 nm. The center wavelengths of the absorption lines 

are certifi ed with expanded uncertainties ranging from 

0.4 pm to 0.7 pm.

2517a High-Resolution 

Wavelength Calibration 

Reference for 1510-1540 

nm – Acetylene (12C2H2)

Fiber-coupled molecular gas absorption cell with narrow 

absorption lines between 1510 nm and 1540 nm. The center wavelengths of the absorption lines are certifi ed with 

expanded uncertainties ranging from 0.1 pm to 0.6 pm.

2519a High-resolution 

Wavelength Calibration 

Reference for 1530-1560 

nm – Hydrogen Cyanide 

(H13C14N)

Fiber-coupled molecular gas absorption cell with absorption lines between 1530 nm and 1560 nm. The center 

wavelengths of the lines are certifi ed with expanded uncertainties ranging from 0.04 pm to 0.24 pm.

Polarization Mode Dispersion Standards

2518 Polarization Mode Dispersion (mode-coupled)

Simulates mode-coupled PMD in optical fi ber; certifi ed for 

mean DGD from 1480 nm to 1570 nm.

2538 Polarization Mode Dispersion (non mode coupled)

Simulates PMD in discrete components; certifi ed for mean 

DGD from 1250 nm to 1650 nm.

Fiber and Fiber-Connector Geometry Standards

2513 Mode Field Diameter Standard for Single-Mode Fiber

Optical fi ber specimen with cleaved end and calibrated 

mode fi eld diameter.

2520 Optical Fiber Diameter 

Standard

Optical fi ber specimen with cladding diameter values 

known to approximately ± 40 nm.

For additional technical information contact:

Optoelectronics Division (815.00)

National Institute of Standards and Technology

325 Broadway

Boulder, CO 80305

Phone: (303) 497-5342 Fax: (303) 497-7671

E-mail: optoelectronics@boulder.nist.gov

For ordering and shipping information contact:

Measurement Services Division

National Institute of Standards and Technology

100 Bureau Drive, Stop 2322

Gaithersburg, MD 20899-2322

Phone: (301) 975-6776 Fax: (301) 948-3730

E-mail: SRMINFO@nist.gov 

THE ELECTRONICS AND ELECTRICAL

ENGINEERING LABORATORY

One of NIST’s seven Measurement and Standards Laboratories, EEEL conducts research, provides measurement services, and helps set standards in support of: the fundamental electronic technologies of semiconductors, magnetics, and superconductors; information and communications technologies, such as fi ber optics, photonics, microwaves, electronic displays, and electronics manufacturing supply chain collaboration; forensics and security measurement instrumentation; fundamental and practical physical standards and measurement services for electrical quantities; maintaining the quality and integrity of electrical power systems; and the development of nanoscale and microelectromechanical devices. EEEL provides support to law enforcement, corrections, and criminal justice agencies, including homeland security. EEEL consists of four programmatic divisions and two matrixmanaged offi ces:Semiconductor Electronics DivisionOptoelectronics DivisionQuantum Electrical Metrology DivisionElectromagnetics DivisionOffi ce of Microelectronics ProgramsOffi ce of Law Enforcement StandardsThis document describes the technical programs of the Optoelectronics Division. Similar documents describing the other Divisions and Offi ces are available. Contact NIST/EEEL, 100 Bureau Drive, MS 8100, Gaithersburg, MD 20899-8100, Telephone: (301) 975-2220, On the Web: www.eeel.nist.gov