***Areas of particular interest:***

***Quantum Dot Morphology***

A Roshko 50.81.52.B4379

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 reflected
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 fields. 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***

KA Bertness 50.81.52.B5883

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 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 significantly
enhance the flexibility and sensitivity of the instrument. Because of
its fast time response, cavity ring-down spectroscopy is also useful for
measuring time-dependent effects and confirming the efficacy of
purifiers. 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***

R Mirin 50.81.52.B3901

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. Specifically, 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***

R Mirin 50.81.52.B4380

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
finite difference time domain software for electromagnetic modeling.

***Optical Spectroscopy of Quantum Dots***

R Mirin 50.81.52.B5884

Self-assembled semiconductor quantum dots have been demonstrated for
many optoelectronic devices (lasers, optical amplifiers, 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.

***Coherent Spectroscopy of Quantum Dots***

R Mirin 50.81.52.B6459

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***

R Mirin 50.81.52.B5885

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***

R Mirin T Clement 50.81.52.B6460

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 (loop-hole free Bell
measurements). We are particularly interested in utilizing our high
quantum efficiency 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***

NA Sanford JB Schlager 50.81.52.B4766

Near-field 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 multi-photon 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,
multi-photon 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 fields 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***

NA Sanford KBertness ARoshko 50.81.52.B5887

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 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 purification), and field
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-field 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, field-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***

KA Bertness RK Hickernell 50.81.52.B1560

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 reflectance)
correlated with reflectance high-energy electron diffraction, *ex situ*
x-ray diffractometry, photoluminescence spectroscopy, optical
reflectance, and extensive modeling capabilities. Other resources
include *in situ* mass spectrometry, atomic force microscopy,
transmission electron microscopy, electrochemical profiling, and clean
room facilities for processing test and device structures. We have
recently demonstrated growth of GaN nanowires, and proposals specific 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.

***Superconducting and Nanometer-Scale Devices for Infrared to
Millimeter-Wave Applications***

E Grossman 50.81.72.B1533

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
specific 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
high-sensitivity bolometers and superconducting multiplexers based on
SQUIDS. Other devices of interest include high-Tc superconducting
bolometers; room-temperature, thin-film bolometers; lithographic and/or
micromachined coupling structures, particularly antennas and integrating
cavities; superconducting mixers/rectifiers; and room-temperature
mixers/rectifiers (e.g., lithographic metal-insulator-metal diodes).

***Flat Panel Display Metrology***

EF Kelley [(Boulder)]{.underline} 50.81.11.B4369

[PA Boynton (Gaithersburg]{.underline})

NIST's flat 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 flat panel displays has become a growing need
for US industries. Good display measurement methods are needed for
several reasons: (1) specification language needs to rest solidly upon
good metrology, (2) fierce competition between technologies requires
good metrology to distinguish features, (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 reflectance characterization, measurements, and modeling
using the bi-directional reflectance distribution function.
Opportunities are available at both Boulder and Gaithersburg campuses.

***High Speed Optoelectronics Measurements***

PD Hale DF Williams 50.81.52.B4008

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.

***High-Speed Optical Receivers and Optoelectronic Integrated
Circuits***

PD Hale RP Mirin DF Williams 50.81.52.B4767

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***

PD Hale KB Rochford 50.81.52.B4381

CM Wang KA Remley DF 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 through 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
50.81.52.B6461***

PD Hale KB Rochford

CM Wang KA Remley DF 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 filtering. We
are soliciting methods for characterizing equalization and dispersion
compensation methods, and particularly their efficacy for correcting low
probability impairments.

***Waveform Metrology***

PD Hale 50.81.52.B5521

Current techniques used by industry for characterizing digital
waveforms, both electrical and optical, are qualitative at best. As a
result, the specifications 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.

***Tunable Laser Ensemble Development for*** ***Laser***
***Radiometry***

JH Lehman 50.81.52.B5888

The calibration of laser and optical fiber meters over wavelengths
ranging from 200 nm to 1800 nm requires laser sources that are stable,
broadly tunable, and having well defined 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 fiber. This will
enable cost-efficient, 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 with standards laboratories around the
world as well as manufacturers of laser and optical fiber power
measurement equipment. Several new projects are 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***

JH Lehman 50.81.52.B5889

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-efficient, routine calibrations having low uncertainties
must be considered. Topics of interest also include new technologies
and/or methods for developing and transferring detector-calibration
information from one area to another.

***Ultraviolet Laser Metrology***

J Lehman ML Dowell 50.81.52.B1563

In recent years, ultraviolet (UV) laser---specifically diode
lasers---have found increased use in a variety of industrial,
commercial, homeland security and medical applications. For example
applications range from high definition digital video to detection of
chemical and biological aerosols. Presently there is no primary standard
for calibration of high-power continuous laser power meters. Aging and
hardening of materials exposed to UV laser radiation is among the
challenges to developing new measurement tools. Presently we are
pursuing carbon nanotube based coatings for thermal detectors as well as
optoelectronic means of creating artificial spectra for calibration of
chemical, biological and explosive sensors. Our work includes the
development of high-accuracy UV primary and transfer standard detectors,
beam profile characterization, laser power, energy and dose measurement
services.

***Optical Coherence Tomography***

SD Dyer PA Williams 50.81.52.B5890

Optical coherence tomography (OCT) is an exciting technique to achieve
high-resolution, three-dimensional, *in vivo* images of human tissue.
OCT has excellent spatial resolution (1-10 micrometers), which is two
orders of magnitude better than ultrasound. OCT has applications ranging
from early detection of glaucoma to measuring the morphology of the
arterial plaques that may be responsible for 70 % of heart attacks. Our
work is focused on developing accurate, high-resolution OCT
measurements. We are applying OCT to measurements of tissue dispersion
and absorption for tissue identification and early disease diagnosis. We
are particularly interested in proposals on the topic of Mie scattering
theory applied in a multiple scattering geometry. Another interest is
minimum phase and non-minimum phase filters, and their applications to
tissue measurements. We are also developing high-accuracy polarization
sensitive OCT measurements to assess tissue anisotropy as a measure of
tissue health.. We are also studying the sources of the polarization
speckle noise that degrades these measurements. The accuracy of OCT
distance measurements is limited by the scattering, absorption,
dispersion, and birefringence of the tissue, as well as the lack of
high-accuracy data on the refractive indices of various human tissues.
The refractive index is important because OCT measures the optical path
length, which is the product of the layer thickness with the group
refractive index. To address this problem, we would like to develop
techniques to accurately measure both thickness and refractive index.

***Fiber-Optic Sensors***

SD Dyer 50.81.52.B5522

Fiber-optic sensors are lightweight, tiny, and flexible, with low power
requirements and large dynamic range. They can detect a variety of
measurands, including strain, temperature, pressure, and electromagnetic
quantities. Much of our research focuses on fiber Bragg gratings (FBGs)
for strain, temperature, and pressure sensing. We are interested in
developing high-accuracy wavelength measurements for sensor calibration.
Because hysteresis and nonlinearity due to the FBG's polymer coating and
adhesives affects sensor calibration, we are also interested in novel
measurement techniques to characterize these effects. Other important
topics include techniques for distributed sensing with high-spatial
resolution (\<100 micrometers), and understanding and improving the
process of writing Bragg gratings in optical fibers.

***Infrared Frequency Comb Development and*** ***Application***

NR Newbury 50.81.52.B5523

A supercontinuum of light that spans over an octave in frequency can be
generated by launching pulses from femtosecond fiber lasers into highly
nonlinear optical fiber. 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 fiber 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, coherent communication or optical
coherence tomography applications.

Optoelectronics Division (815.00)

National Institute of Standards and Technology

325 Broadway

Boulder, CO 80305-3328

[http://www.boulder.nist.gov/div
815/](http://www.boulder.nist.gov/div 815/)

<http://www.nist.gov/oiaa/postdoc.htm>

Ph: (303) 497-5342

Fax: (303) 497-7671

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NRC/NIST Postdoctoral Research Associateships

The **Optoelectronics Division** of the National Institute of Standards
and Technology invites applications for postdoctoral research awards in
optoelectronics

[*Eligibility*:]{.underline} Must be a U.S. citizen and within five
years of doctorate

[*Duration*:]{.underline} Two years, maximum

[*Location*:]{.underline} Boulder, Colorado

[*Stipend*:]{.underline} \$55,700 plus \$5,500 to support professional
travel, books, incidental research expenses

*[Benefits]{.underline}*: Relocation expenses, health and life
insurance, retirement plan

*[Deadline]{.underline}*: The first deadline for applications is
February 1, 2007 for appointments beginning between July 1 and December
31, 2007; the second competition\'s deadline will be August 1, 2007 for
appointments beginning between January 1 and June 30, 2008.