bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiwave mixing mediated phase-conjugation devices: theory and experiment
Authors: Khoo I. C. , Wang Wei , Liand Yu , Li Hong , LoPresti P. , Zhou P. , Linquist R. G.
Published: February 2023

Throughout the visible, near- and far-infrared spectral regimes, the extraordinarily large Kerrlike non linearities of liquid crystals may be utilized in conjunction with newly observed multiwave mixing (stationary and transient) effects for applications in phase conjugation and other self-pumped oscillators. For long wavelengths, or small wave mixing angles, the usual thin film geometries of liquid crystals naturally produce side diffractions; also, the Kerrlike responses of liquid crystals give rise to strong phase modulation effects. Our theories quantitatively account for these factors as well as other equally important intensity, temporal, and material parameters.
High-power AlGaInP lasers
Authors: Bour David P. , Serreze Harvey B.
Published: February 2023

High-power AlGaInP diode lasers in the 600-nm wavelength band are being developed for many applications. To date, most commercial devices are double heterostructure lasers, usually narrow, index guided stripes intended for optical recording, laser printing, and holographic scanners, with λ ~ 670 nm, and power ~5–20 mW. For pumping chromium-doped solid-state laser materials, however, higher power diodes are required. This is particularly difficult, because the high thresholds and poor thermal conductivity of AlGaInP lasers make heating a serious problem for high-power operation. Using quantum well structures, however, substantial performance improvements have been achieved. For example, using a strained 70-Å single quantum well with graded-index optical confinement, powers exceeding 400 mW (cw) and 4 W (pulsed) at λ = 670 nm have been obtained. That is possible because of the diode’s low threshold current density of <400 A/cm2. Thin GaInP quantum wells and quaternary AlGaInP active regions have also led to shorter wavelength lasers. For cw operation of thin MQW structures, for example, wavelengths of 630 nm are now possible. This overlaps the He-Ne laser and also lies closer to the peak of the broad 600-nm absorption of chromium in solid-state hosts.
Thermooptical switching in Si etalons
Authors: Feng Shangting , Irene Eugene A.
Published: February 2023

Optical switching in thermooptical Si etalons has been demonstrated. In initial experiments a pulsed CO2 laser beam is used to heat a Si etalon and shift the interference fringe of a 1.1- and 1.5-μm probe beam. It is shown that the switching time can be greatly reduced from ms to μs by choosing a probe beam of shorter wavelength in an external switching configuration. The switching time has further been improved to the ns range by the use of a 1.06-μm Nd:YAG laser pump which is presumed to give rise to a thermorefractive change in the Si etalon; at the same time, the switching threshold energy has been reduced to ~1 μJ compared with ~1 mJ for a CO2 laser pump. Different etalons with thicknesses of 400 μm, 72 μm, and 1.5 μm have been examined to optimize the switching characteristics. We find that the 72-μm etalon exhibits the best behavior in terms of low power threshold, high speed, and contrast. In addition, the pump power dependence of the signal pulse shape has been investigated which indicates a multiple interference fringe shift and transverse thermal relaxation dynamics. Finally, by aligning one etalon at switch-on and another at switch-off, we demonstrate a write and erase optical logic system.
Optics for wavelet-based processing
Authors: Li Yao
Published: February 2023

Recent developments in signal processing, vision, and image understanding reveal that a proper signal or image decomposition before the actual processing may provide enormously useful information about the signal or image. The wavelet transform a particularly useful model, provides a multi resolution linear signal/image time-frequency or space-frequency decomposition tool. Successful applications of wavelet transforms to solve difficult signal or image analysis and synthesis problems have been widely reported. Digital implementations of these transforms are computationally intensive both because of the nature of the coordinate doubling of the wavelet transform and because of the large quantity of convolution/correlation operations that accompany them. Optics with its inherent parallel processing capability, has been used to obtain many useful linear signal/image transformations and will certainly have some roles in wavelet-based processing. This survey talk is intended to outline the suitability of using existing optical processing techniques for wavelet-based signal/image analysis and synthesis. A brief summary of various proposed optical wavelet transform approaches together with their advantages and constraints will be presented. Possible future directions in this new research field will also be discussed.
Neural network adaptive wavelet transform
Authors: Szu Harold
Published: February 2023

Daughters

{

h

a
b

(
t
)
=
h
[
(
t
−
b
)
/
a
]
/

a

}

constructed by dilation aand shift bof a single mother wavelet h(t) form the basis of the wavelet transform (WT) coined by French geologists Morlet et al.in 1985. The physics behind the WT is a bank of matched filters1of a constant resonator Qfor seismic imaging. The condition to be a mother wavelet is to be zero-dc square integrable. Let the Fourier transform (FT) be the inner product:

FT
{
e
}
=
(
s
,
e
)
=

∫
s

(
t
)
e
(
t
)
d
t

, with e(t) = exp(2πjft). Then a windowed FT becomes the Gabor GT{s} = (s,g), where g(t) = exp[−(t/τ)2]exp(2πjft), and Morlet's WT{s} = (s,gab), where

g
a
b

(
t
)
=
g
[
(
t
−
b
)
/
a
]
/

a

. Applications are based either on an efficient, faithful, noise-immune wide band transient representation or on a sensitive, robust, truthful signal classsification. While the former optimizes the majority signals' energy, the latter works on the overlapping boundary and outliers. A superset of mother wave lets is introduced for adaptive WT using neural nets to explain the cocktail party hearing effect.
Packaged optical interconnection system based on the correlation matrix tensor multiplier algorithm
Authors: Takahashi Hidemi , Zaleta David , Ma Jian , Ford Joseph E. , Fainman Yeshaiahu , Lee Sing H.
Published: February 2023

A unique method to achieve high fan-out optical interconnections based on the correlation matrix-tensor multiplier (CMTM) algorithm has recently been demonstrated.1 We present a new packaged version of this optical system that is amenable to integration with opto-electronics. In this system, a random phase-encoded input array is optically correlated with a recorded control pattern that stores the pre-determined interconnections by utilizing photorefractive four-wave mixing. A random phase plate, a LiNbO3 crystal, and two computer-generated holograms (CGHs) have been integrated on one surface of a glass substrate of dimensions 80 × 80 × 44 mm. The CGHs (12 mm aperture) are designed by Code-V and fabricated by using direct-write e-beam lithography. The correlated output is observed by a CCD camera. Optical interconnection between 5×5 arrays is demonstrated. Reconfiguration between the pre-stored interconnections is possible by using wavelength multiplexing to store different control patterns in the photorefractive crystal. Details of the system design and experimental results are described.
Anisotropic cross talk in optical interconnection by using a self-pumped phase conjugate mirror at the Fourier plane
Authors: Chiou Arthur
Published: February 2023

In optical neural networks, interconnection of two-dimensional planes of neurons is facilitated by the large storage capacity and high Bragg selectivity of volume phase holograms. In spite of the high Bragg selectivity, cross talk due to the conical Bragg degeneracy remains an issue. In a recent paper, Owechko and Soffer1 proposed using the spatially and angularly multiplexed holograms in a self-pumped phase conjugate mirror (SPPCM) at the Fourier plane to provide the global inter-connection and to reduce the holographic cross talk between planes of neurons. In this paper, we describe experimental evidence and give physical explanation of the drastic difference in cross talk (in optical interconnection using SPPCM at the Fourier plane) with respect to points along the horizontal versus those along the vertical directions. We show that the removal of Bragg degeneracy applies only in the horizontal but not in the vertical direction. The observation and explanation reveal that similar anisotropic behavior can be expected in other parameters as well under rather broad conditions.
Free-space optical bus-based wavelength division multiple access (WDMA) networks
Authors: Li Yao , Lohmann Adolf W. , Rao Satish B.
Published: February 2023

A novel optical free-space mesh-connected bus (MCB) interconnect network architecture is proposed. A MCB (Wittie, 1981) is known to have the capability of interconnecting, by using a three-stage switching, N nodes with a power distribution loss (PDL) proportional to

N

, and is therefore advantageous for networking a large number, say, over 1000, of communicating ports. Based on conventional space-invariant optical components in a compact and efficient geometry, the proposed optical MCB system concept can be used to build either free space optical interconnect links for parallel processing applications or central switching systems for local or global light wave communication networks. By using the WDMA concept, various optical system implementation and performance issues, such as dispersion and aberration-limited interconnect capacity, power, and volume consumption efficiency, are discussed and parameters are analyzed. It was found that by using a reasonably compact three-dimensional free-space volume, more than 100,000 dispersion limited communication nodes at a uniform channel spacing of 0.75 nm can be linked with a moderate PDL of 28 dB. Some preliminary optical WDMA MCB experiments based on a 27 × 27 panchromatic optical source array were per formed to confirm the operational principle of the proposed concept.
Bayesian framework for calculating observer performance
Authors: Myers K. J. , Wagner R. F.
Published: February 2023

The Bayesian or ideal observer is a construct from signal detection theory. By definition, the ideal observer uses all information present in an image to make optimal decisions regarding the underlying scene. By comparing the calculated performance of the ideal observer to the measured performance of a human observer, we can determine how well a displayed image is utilized by the human observer. Human performance has been shown to be highly efficient for certain, detection and discrimination tasks. Degradations in human performance due to correlated noise or uncertainty in the task have been explained by using this Bayesian framework. This talk will describe the ideal-observer decision function for various tasks and methods for calculating the ideal-observer SNR. Existing data comparing the ideal and human observers for a variety of visual tasks will be reviewed.
Logic with optical fibers by using cross-phase modulation
Authors: McAulay Alastair D. , Xu Xin , Wang Junqing
Published: February 2023

We consider the feasibility of performing logic with optical fibers at low powers. A Mach-Zehnder interferometer consists of two optical fibers. We consider the circular interference fringes between the outputs of the two fibers. A laser beam with a different wavelength is coupled into one of the two fibers to provide an increased intensity in that fiber. This effect will cause the index of refraction to change in that fiber because of nonlinearity. Since the interference fringes are very sensitive, a small change due to phase modulation will cause the pattern to move. Therefore, we do not need high power. The different combinations of the input presence and absence for the two laser beams will give different interference patterns at the output. Logical operations are obtained if a detector is placed at a particular position in the output.
Photonic ionic cloth radio amplifier for pumping IR radiation from living systems
Authors: Callahan Philip S.
Published: February 2023

Unfinished flax, Linum usitatissimum, soaked in a special ionic electrolyte and sandwiched between two cloth dielectrics (wool) is impedance matched to a de Tektronix 222 digital oscilloscope and used to amplify and detect ELF Schumann atmospheric waves between 1 Hz and 20 kHz. Preliminary experiments (oscilloscope recordings) indicate that the ELF Schumann frequencies vary according to geographic regions, e.g., 8 Hz in Ireland, 16 Hz in California, 24 Hz in Florida. Higher frequencies in the 1000 Hz to 2000 Hz electrical anesthesia portion of the spectrum are also evident. The ionic flax fibers act as photonic dielectric waveguide detectors for long wave ELF. Preliminary experiments indicate that atmospheric Schumann energy, which penetrates soil and living organisms, e.g., humans, acts as pump frequencies in photonic infrared communications (room temperature, 10 μm) between the cells of living organisms. The rise in blackbody IR temperature, measured when the photonic ionic cloth radio amplifier is placed against the skin, is between 0.5 and 1°C above room temperature. Further experiments are planned to determine if nonlinear coherent Cabannes scatter IR lines (surface enhanced) from skin are amplified by ELF pumping amplification. Life is photonic!
Manifestation of Berry’s phase in image bearing optical beams
Authors: Segev Mordechai , Solomon Richard , Yariv Amnon
Published: February 2023

We show that when an image bearing optical beam acquires a Berry phase during its propagation in a nonplanar optical system, its image is rotated by an angle identical to this phase in magnitude, but with an opposite sign, about one, well-defined, axis. Therefore, a measurement of the topological Berry phase of a given optical system can be performed by a direct measurement of the angle of rotation of its image about its optical axis. We show that since our method of measuring the Berry phase does not involve any coherent effects, it may be implemented with coherent as well as incoherent illumination. We demonstrate these arguments experimentally by measuring the Berry phase of a nonplanar optical system, using an incandescent light bulb, and compare it to conventional polarization based methods.
Conical scattering from a one-dimensional random surface
Authors: McGurn A. R. , Maradudin A. A. , Luna R. E. , Mendez E. R. , Gu Zu-Han
Published: February 2023

We study theoretically and experimentally the scattering of light from a one-dimensional, random metal surface when the plane of incidence is parallel to the generators of the surface and perpendicular to the mean surface. The incoherent component of the scattered light is found to be confined to a conical surface whose axis of rotation is the intersection of the plane of incidence with the mean surface. Scattering anomalies associated with weak localization are observed in both co-polarized and cross-polarized scattering. Theoretical results are presented for the scattering of visible light from both silver and gold surfaces. Experimental data displaying these anomalies are presented.
Characterization of low loss, high reflectivity dielectric mirrors
Authors: Fishman I. M. , Haar P. , Smith T. I.
Published: February 2023

Precise characterization of low loss, high reflectivity dielectric mirrors can be difficult with conventional techniques, such as FTIR and ring-down measurements. Ring-down measurements, ordinarily well suited to the characterization of low loss mirrors, are questionable when the reflectivity loss is smaller than intrinsic cavity losses. We have developed a technique for measuring the reflectivity of low loss dielectric mirrors that uses the intensity of light reflected from the cavity at resonance. Since the measurement is fundamentally an interference measurement between the wave reflected directly from the cavity mirror and the portion of the cavity field transmitted through the mirror, the technique is quite sensitive. Using a 12.7 m cavity and a 3.39 μm He-Ne laser, we have measured mirror losses as small as 0.01 % in a cavity with 0.3% intrinsic losses.
State-selective laser photodissociation of sodium dimer B1Πu state by optogalvanic spectroscopy of hybrid transitions
Authors: Naqvi Athar S. , Naveedullah K. , Azzeer A. M. , Al-Salhi M. S.
Published: February 2023

For alkali metal dimers the B1Πu state is attractive with a repulsive hump at large internuclear separations. For sodium the correlation of this state with the dissociation atomic product states has been studied by laser absorption spectroscopy using an ion-detection/boxcar integration technique. The dye laser scan at the correct range of photon energies produces a hybrid transition comprising the molecular component from ground state

x
1

Σ
g
+

to the dissociation hump of B1Πu and the atomic component at the some photon energy from product 3 2P1/2,3/2 states to an atomic Rydberg state. A molecular absorption band is identified that leads to population inversion between sodium 3 2P1
/2,3/2
and 3 2S states.
Squeezed quantum noise effects in intrinsic optical bistability
Authors: Singh Suneel , Bowden Charles M.
Published: February 2023

We analyze fluctuation effects of a squeezed electromagnetic reservoir (also termed squeezed vacuum, or SV) on the phenomenon of intrinsic optical bistability (IOB) in a dense collection of two-level atoms. A quantum statistical treatment is developed in the limit of a bad cavity and large dephasing in the medium. Under these conditions we obtain a single operator Langevin equation for the atomic inversion by adiabatic elimination of the atomic polarization variables. By using Ito calculus, the corresponding Fokker-Planck equation is derived, the stationary solution of which yields the probability distribution function for the bistable system as a function of the inversion. In a narrow region of transition, the probability distribution is double peaked with the two peaks corresponding to two metastable states in IOB. Quantum fluctuations can induce the system to jump randomly from one metastable state to the other with certain characteristic (passage) times. Squeezed quantum noise (as in the SV) is found to result in drastic alteration of the intrinsic bistable behavior of the system. Interestingly, the probability distribution and the passage times now exhibit critical dependence on the relative phase between the external driving field and the squeezed vacuum.
Increased modulation depth of submicrometer gratings produced by photoelectrochemical etching of GaAs
Authors: Twyford E. J. , Kohl P. A. , Jokerst N. M. , Hartman N. F.
Published: February 2023

Submicrometer optical diffraction gratings with improved modulation depth were photoelectrochemically etched on n-GaAs. This etching technique uses an elevated etchant temperature to exceed the spatial resolution limits imposed by etching at room temperature and provides a method of photoelectrochemical etching of gratings whose period is shorter than those of previously reported photoelectrochemically etched gratings. The improved grating modulation depth, the result of an increase in electrolyte temperature, was experimentally measured by etching 0.28 μm period gratings at five different temperatures. These results are compared with theoretical predictions based on analytical expressions for the reaction rate at the etched surface. Experimentally, a 25°C increase in the etching temperature improved the grating amplitude by a factor of 1.7, which is in agreement with the theoretical predictions.
Massively parallel solution of scattering from doubly periodic structures
Authors: Sohail S. , Naqvi H. , Leland Robert
Published: February 2023

Using the technique of coupled waveform analysis, we have formulated a set of equations that rigorously describes forward electromagnetic scattering from double periodic structures. For geometries of practical interest the cost of solving these equations on traditional vector supercomputers is unacceptable, so we have developed a parallel algorithm for solving them on distributed memory multiprocessing systems, where the expected cost of computation is much lower. We have implemented our algorithm on a 1024-node hypercube nCUBE2 parallel supercomputer and tested it on various geometries arising in a laser diffraction study of integrated circuits. We will describe our algorithm, characterize its performance, and offer comparisons with implementations on a typical workstation and a vector supercomputer.
Polarization components designed by using form birefringence
Authors: Raguin Daniel H. , Morris G. Michael
Published: February 2023

Through the use of subwavelength stratification, media having nearly arbitrary birefringence can be fabricated. By making the stratification period sufficiently fine so that no diffracted orders propagate, light will not resolve the periodicity. Light will instead react to the stratified region as if it were encountering a single medium having an effective index of refraction and conductivity. As has been reported by several authors,1,2 these effective optical properties are polarization dependent. This effective birefringence, or form birefringence, can be applied towards the creation of polarization components, such as wave plates, beam splitters, and polarization rotating mirrors. We present designs for such components using effective medium theory (EMT) and rigorous coupled-wave analysis (RCWA). Structures are designed for both the visible and infrared portions of the spectrum. Polarizing gratings can be manufactured by using holography or optical lithography. Stratified media may also be grown one layer at a time by using various deposition techniques, such as sputtering and molecular beam epitaxy (MBE).
The appearance of the Sun through clouds
Authors: Linskens Jeffery , Bohren Craig F.
Published: February 2023

When the Sun or Moon can be seen through clouds, the edge is usually sharp and well defined. Less frequently, but not rarely, the edge will appear hazy or fuzzy through dense cirrus or cirrostratus clouds. Both phenomena have been photographed, and the cloud types associated with each sighting have been analyzed. Simple experiments involving a luminous disk and a variety of scatterers and optical depths have been performed to create both hazy and sharp images. Also, Monte Carlo techniques have been used to investigate under what conditions multiple scattering by clouds can cause the hazy image of the Sun. How horizontal inhomogeneity in clouds on a scale less than the solid angle of the Sun affects the image observed has also been investigated.
Influence of field of view on the performance of Fizeau interferometers
Authors: Greenebaum M. , Shultz T. , Brenner D. , Elbaum M.
Published: February 2023

We have been investigating the transmission profile of a multi-beam Fizeau interferometer (MBFI) illuminated by mutually coherent light incident from several directions at once. We report calculations of the field-of- view (FOV) dependence of the transmission line shape and the results of laboratory measurements that explore the validity of these calculations. The experiments were done with a temperature stabilized MBFI that analyzed collimated light scattered from a rotating diffuser that was illuminated by a stabilized He–Ne laser (623.8 nm) through intermediate optics that varied the FOV. The fringes were scanned either by a photo-multiplier or by a linear photodiode array and were digitally recorded. At fixed incidence angle, measured fringe profiles agree with standard calculations.1,2 The laboratory data for FOVs ≤1 mrad are compared with the results of our code, which employs two-dimensional numerical integration over incidence angle to approximate the effects of fringe superposition.
The role of coherent interactions in pulse shaping in passively mode-locked lasers
Authors: Beck M. , Koshel R. J. , Walmsley I. A.
Published: February 2023

As the duration of pulses generated by passively mode-locked lasers decreases, the pulse bandwidth becomes a significant fraction of the avalable gain bandwidth. When this occurs, it is necessarily true that the response of the polarization of the gain medium does not follow the electric field of the pulse adiabatically. Thus, one cannot use the Franz-Nodvik model1 for the amplification (or absorption) portions of the pulse shaping. The study of the coherent amplification of short pulses is well developed,2 but most schemes require a numerical solution to the Maxwell-Bloch equations that is both complicated and time consuming and is therefore unsuitable for a model of a mode locked laser, in which the pulse must be propagated through several cavity elements many times. Thus we have developed an approximate solution to the Bloch equations that accounts for the coherent parts of the interaction, at least to first order, so that we may assess the importance of coherent amplification on the shaping of ultrashort pulses in mode-locked lasers. We compare the results of our numerical model with the measured pulse shapes from a colliding-pulse mode-locked dye laser and discuss some of the implications of the coherent part of the light-matter interaction in setting a lower bound for the pulse duration.
Design of a reflective optical ring array interconnect
Authors: Ha Berlin , Li Yao
Published: February 2023

We present a reflective optical ring array interconnect architecture for handling data routings under various SIMD digital array processing environments. The proposed architecture can perform clock-skew-free optical data permutation ranging from a fixed degree model, such as a nearest-neighbor, to a variable degree model, such as a plus-minus-2
i
networks. It was found that the space-variant routings that are difficult to perform in a rectangular array OEICs can easily be mapped into rotation-invariant routings to be optically implemented via conventional optical components. Our system aberration study also shows that the design of the supporting optical imaging system for the proposed architecture is much more easily handled than that using a conventional rectangular array topology. Design principles for both the involved individual optical components and the entire optical system are described. The optical network performance parameters, such as the diffraction- and aberration-related processing capability, the optical transmitter coupling efficiency, the optical free-space power distribution loss, the detector dynamic range requirement, and the power-dependent elemental-bit-rate, are analyzed.
Surface roughness requirements for SXPL optics
Authors: Windt D. L. , Waskiweicz W. K. , Griffith J. , Grigg D. A. , Himel M. D.
Published: February 2023

To date there has been little research directed at correlating variations in peak normal-incidence soft x-ray reflectance of multilayer-coated optics with measured surface roughness. This information would be useful to those involved in both the specification and fabrication of figured optics for soft x-ray projection lithography (SXPL). The work presented here is focused on the characterization of the high-spatial frequency topography, which causes reduced soft x-ray reflectance. We have deposited Mo/Si multilayers on polished substrates of various materials obtained from several commercial suppliers. The multilayers consisted of 40 bilayers of Mo/Si, having a period of ~75 Å, appropriate for use at near-normal incidence at a wavelength of around 140 Å. The soft x-ray reflectance of these samples was measured by using a laser plasma-based soft x-ray reflectometer. Surface topography was measured by using both a commercial optical profilometer (Wyko Corp., TOPO-3D, 20× and 40× objectives) and an atomic force microscope (AFM), thereby covering an overlapping range of spatial wavelengths extending from 50 Å to 438 µm. Our results indicate that the soft x-ray reflectance is most sensitive to spatial wavelengths in the range extending from ~50 Å to 10 µm. Most of this range of spatial wavelengths is inaccessible by conventional contact and non-contact profilometers, though it is readily accessible by using the AFM.
Optical performance of internally cooled seeker windows
Authors: Armitage D. , Benson R. S. , Jayadev T. S. , Williams W. S.
Published: February 2023

A window for an endo-atmospheric seeker optical system must maintain its optical quality while being subjected to high heat input from an external flow. We have analyzed the optical effects associated with coolant channels that are internal to the window and that control temperatures within the window material. These channels partially obscure the clear aperture, and temperature gradients between channels cause spatial variations in optical path through the window. In the seeker's image plane the intensity distribution is affected by amplitude and phase aberrations associated with the coolant channels. We have modelled the window temperature distribution for various channel structures, calculated the window infrared thermal emission, and predicted image-plane intensity distributions. Design tradeoffs for optimum performance will be discussed.
Global invariance and noninvariance of spectra on propagation in free space
Authors: Wolf Emil
Published: February 2023

It is shown that within the framework of exact statistical wave theory there is no realizable source that generates a field whose normalized spectrum is invariant on propagation, i.e. that is the same at every point outside the source domain. This result is established for three-dimensional primary sources and also for two-dimensional secondary sources. Nevertheless, as we will also demonstrate, there are sources that generate spatially invariant fields to a good approximation.
Imaging optically thick objects in scanning microscopy
Authors: Aguilar J. F. , Méndez E. R.
Published: February 2023

A numerical technique to calculate images of optically thick one-dimensional objects in scanning optical microscopy is described. Two kinds of samples are considered: In one case, the sample consists of a semi-infinite material characterized by its profile and complex refractive index. In the other case, the semi-infinite material is coated with a layer of a different material. The technique employed to calculate the scattered field is based on Green’s integral theorem. Since the boundary conditions are calculated rather than postulated, this technique is considered rigorous. Calculated images of several samples of conducting and dielectric materials in various modes of image formation will be presented.
Equivalence of twin beams and squeezed states in a nondegenerate optical parametric amplifier
Authors: Kim Chonghoon , Kumar Prem
Published: February 2023

Twin beams generated from a nondegenerate optical parametric amplifier (NOPA) of gaing possess1 an intensity correlation that falls below the quantum limit by (2g – 1). This occurs whenever the input idler to the NOPA is in the vacuum state. Such input is practically advantageous because it makes the NOPA output intensities phase insensitive. When a non-vacuum idler input state is chosen, the NOPA output intensities become phase sensitive. For a proper input state and a suitable pump phase the output intensity correlation falls below the quantum limit by

(

g

+

g
−
1

)

2

, which is 3 dB superior to the vacuum-idler-input result for g >> 1 and is equivalent to the quantum-noise reduction obtainable from a squeezed state generated with the same gain. Thus the sensitivity improvement achievable with NOPA twin beams by using direct detection is equivalent to that obtainable with squeezed states by using homodyne detection. The above equivalence also provides a new scheme for the generation of pulsed squeezed light that, in addition to being simple, automatically generates a matched local oscillator2 for homodyne detection of the squeezed pulses.
Diffractive relief structure adjustment under recording on dry polymer
Authors: Boiko Yu. B. , Calixto S.
Published: February 2023

The resolution power of dry photopolymer films for the relief recording of computer-generated diffractive optical elements (without processing) is not more than 30 lines/mm. This and also the nonlinearity of the recording response due to the dye bleaching effect should be taken into account in adjusting the final relief surface shape of the diffractive zones. Such accounting has been done on the amplitude mask preparation stage by introducing corrections into generated amplitude function. Nonlinear correction has been found to match well the nonlinearity of the polymer response. Adjustment of the relief structure zones' top and bottom levels has been measured. Recording layer chemical content has been found to influence the relief shape correction. In particular, for the layers with sufficient optical density the effect of relief self-correction has been observed.
Highly accurate infrared emission measurement
Authors: Revercomb Henry E.
Published: February 2023

Fourier transform infrared (FTIR) instruments have been used to make radiometrically accurate measurements of atmospheric emission from high altitude aircraft and from the ground. These demonstrate a wide range of capabilities for routine remote sensing from ground-based and spacecraft facilities. Applications of this type of observation to atmospheric remote sensing include the measurement of temperature, water vapor, and trace gas profiles; cloud heights, effective particle sizes, and phase; and surface temperatures and emissivities; these are in addition to the direct radiances for climate change studies and for atmospheric spectroscopy. The FTIR instruments currently in use at the University of Wisconsin are the High-Resolution Interferometer Sounder (HIS) aircraft instrument (NASA ER-2 aircraft), the ground-based "baby" HIS, and the DOE Atmospheric Emitted Radiance Interferometer (AERI). These instruments are designed around commercially available interferometers from Bomem, Inc., and make use of precise reference blackbodies for calibration. The extensive observations from these instruments cover the spectral region from 3.6 to 20 μm with resolving powers of 1000 to 4000. Experience with these instruments has also led to several spacecraft instrument designs.
Recent results from analysis of high resolution infrared atmospheric and laboratory spectra
Authors: Goldman A. , Murcray F. J. , Blatherwick R. D. , Murcray F. H. , Kosters J. J. , David S. J. , Murcray D. G. , Rinsland C. P.
Published: February 2023

High resolution (0.002-0.003 cm-1) Michelson type interferometer systems have been used to obtain infrared solar absorption spectra of the stratosphere during several balloon flights, as well as ground-based solar spectra and laboratory spectra of molecules of stratospheric interest. The stratospheric spectra cover the 700-2200 cm-1 region and show many new spectral features of important atmospheric gases, such as O3 (and isotopes), NO2, HNO3, O2, and COF2. Analysis of these features, combined with new theoretical and laboratory studies of the molecular absorption spectra, improves the spectral line parameters (mostly line positions, intensities, and pressure broadening) and leads to more complete lines identification and more accurate retrieval quantification of stratospheric gases. Ground-based spectra in the 3-12 μm region are obtained regularly from Mauna Loa (Hawaii) and Colorado, in support of the Network for Detection of Stratospheric Change (NDSC) and NASA Upper Atmosphere Research Satellite (UARS). Analysis of the ground-based spectra provides total column density for many gases and some altitude distribution information for species such as O3, HCl, and HNO3, as well as monitoring trace gases during special events, such as the July 1991 observations of stratospheric SO2 from the Mt. Pinatubo eruption.
Dynamic arrays of nonlinearly coupled mode-locked laser oscillators applied to agile beam steering
Authors: Fork Richard L. , Theimer James P.
Published: February 2023

We discuss the dynamics of nonlinearly coupled arrays of mode-locked ultrashort pulse lasers as influenced by small perturbations of the nonlinear coupling parameters. We examine the experimentally observed case, where soliton-like pulse shaping is important and one nonlinear coupling mechanism is attractive and a second nonlinear coupling mechanism is repulsive, as regards the temporal relationship of the pulses in neighboring laser oscillators.1 Small adjustments of the coupling parameters can be used to produce a rich variety of complex dynamical behavior of the coupled system. Of particular interest is the possibility of highly agile beam steering of the coherent optical emission from a two dimensional array of such nonlinearly coupled mode-locked laser oscillators. Large angular range, well defined emission patterns, rapid motion of the beam, and hardware based on compact semiconductor laser components appear accessible by using currently evolving technology. We describe recent experimental results relevant to two such nonlinearly coupled lasers and calculate the properties of larger arrays.
Complete diagnostic of ultrashort pulses by interference in the Fourier space
Authors: Mergler Andreas , Diels Jean-Claude , Lai Ming
Published: February 2023

Different frequency components of an ultrashort-pulse train are transversely separated by a dispersion line consisting of a pair of highly dispersive prisms. The dispersion line is adjusted for zero group velocity dispersion. Cross interference between different sections of the pulse spectrum is made in a modified Mach–Zehnder interferometer. The phase of the central section of the spectrum is chosen as a reference, and the relative phase between the central section and other sections of the spectrum is then determined by measuring the curve of the center of the interference profile. The initial pulses are completely reconstructed with the measured amplitude and relative phase of the spectrum. The whole detection is made by simply using a photon diode array to record the interference pattern. Single shot detection of the pulse is also possible. This ultrashort-pulse diagnostic scheme avoids any nonlinear process and iterative calculation.
Content addressable networks
Authors: Brodsky Stephen A. , Guest Clark C.
Published: February 2023

Content addressable networks (CAN) are a family of network learning algorithms for supervised, tutored, and self-organized systems based on binary weights and parallel binary computations. CAN networks directly address the implementation costs associated with high precision weight storage and computation. CAN networks are efficient learning systems with capabilities comparable to analog networks. Supervised CAN systems use error information for weight corrections in a manner analogous to that of backpropagation gradient descent. The tutored CAN network model uses "yes" or "no" feedback as a guide for forming associative categories. The self-organized model derives corrections internally to form recall categories in an adaptive resonance theory style network. The CAN algorithms derive advantages from their intrinsic binary nature and efficient implementation in both optical and VLSI computing systems. CAN solutions for quantized problems may be used directly to initialize analog backpropagation networks. The CAN network has been implemented optically, with optical computation of both recall and learning. Development of supervised CAN networks in VLSI with learning on-chip continues.
Disk detection in statistically defined backgrounds
Authors: Burgess Arthur
Published: February 2023

This work extends experiments by Rolland1 and uses the theoretical framework of Myers et al.2 The observer task was detection of a flat-top disk signal in white noise added to a statistically defined, spatially varying background produced using low-pass filtered white noise. Six backgrounds were produced using thee Gaussian filter standard deviations and two spectral densities per filter. Two experimental methods were used; 2AFC detection with signal known exactly and MAFC location uncertainty (M = 8,32,98). Human efficiency was compared to that of a Hotelling trace observer normalized to have the same efficiency (50%) as humans for a uniform background. The agreement between human performance and the Hotelling trace model was fairly good.
Wavelength switching and stabilization of semiconductor laser using a HOE
Authors: Zhou H. X. , Tian R. S. , Ih C. S. , Xia X.
Published: February 2023

This paper describes an approach in which the wavelength of a semiconductor laser in an optical WDM communication system is sta­bilized and selected with a HOE. We have analyzed planar and curved as well as reflective and transmissive HOE. The optimum system results can be obtained by optimizing parameters. As an example, the design of a very compact HOE system is illustrated. Because of the lack of ideal IR recording materials, the HOE can be generated by a computer and fabricated by known techniques, such as by using an e-beam machine. We also illustrate an alternative CGH technique. First, a CGH with a prescribed phase distortion for the intended IR HOE is fabricated for a visible wavelength. The desired IR HOE can then be exposed with the visible light by using the pre-distorted CGH. Designs of HOE to be used for wavelengths of 780 nm, 830 nm, 1300 nm, and 1500 nm will be shown. The switchable wavelength spacing is 1 nm with an accuracy of better than 0.1 nm and switchable range is 35 nm. Computer simulations and experimental results will be shown.
IR spectroscopy of molecules attached to liquid He clusters
Authors: Scoles G.
Published: February 2023

Helium clusters containing a few thousand monomers, formed from a sonic nozzle at 15 K, are doped with SF6 molecules that they pick up in a scattering box containing this gas at partial pressures of 10−5 to 10−4 Torr. The IR spectrum of the doped clusters is obtained by line tunable CO2 laser excitation of the SF6 and bolometric detection of the photoevaporated helium atoms. If the clusters contain a single SF6 molecule, the spectrum shows two absorptions located at 945.8 cm−1 and 946.1 cm−1, which indicates that the SF6 molecule is located in an anisotropic environment, i.e., near the surface of the cluster. If the cluster contains two SF6 molecules, the spectrum of the SF6 dimer is recovered and found to be very narrow, as appropriate to the very low temperature of the medium in which the spectrum is taken (~0.4 K). The linear and quadratic dependence of the spectral intensities of, respectively, the monomer and the dimer features allows for an independent confirmation of the average cluster size.
Optical engineering and instrumentation research
Authors: Viswanathan V. K.
Published: February 2023

Optics in New Mexico spans a wide variety of research, design, analysis, manufacturing, and instrumentation activities. The number of individuals and groups involved is also quite large. Historically, the major activities have involved lasers, electro-optics, nonlinear optics, deformable mirrors and phase conjugation, atmospheric optics and beam propagation, spectroscopy, and space optics. The development of various optics codes and manufacturing has also been a major activity. In addition to the above activities, currently there are various groups involved in lithography, image restoration, and enhancement. The manufacturing activities have also expanded into sophisticated areas like materials and metrology involving optics. This presentation will attempt to give details of these areas as well as the groups involved in the activities. Specific examples will be described in some detail.
Optical system design issues for the Altair space experiment pointing and tracking system
Authors: Turner T. S. , Carniglia C. K.
Published: February 2023

Altair is an acquisition, tracking, and pointing (ATP) space experiment sponsored by the Strategic Defense Initiative Organization (SDIO) Directed Energy Program Office. The experiment is configured as a free-flying satellite with an electro-optical payload designed to address target acquisition and pointing issues. The payload was designed by a government-led Phillips Laboratory team. The Altair optical tracking system requires diffraction-limited performance for the IR intermediate tracking camera and the visible fine tracking camera. Size and weight considerations were balanced by the economy of utilizing existing hardware from the Starlab program. A trade study demonstrated that the optical tolerances were equivalent for a Mersenne telescope and a Cassegrain telescope, but that the latter reduced the size of the relay optics considerably. An off-axis parabola used to collimate the light introduces astigmatism and coma, which degrade the images. Diffraction-limited performance was obtained where necessary without introducing additional off-axis elements. In addition, the extent of the point spread function for the visible-intermediate-tracking camera, while not diffraction limited, was less than the pixel size of the focal plane array. An additional consideration was that the pupils remain in registration during beam deflections introduced by the steering mirrors. This requirement was met by placing the steering mirrors close to the pupil locations. The final conceptual optical design for the Altair payload will be presented.
Achievement of sub-nanosecond time resolution with a passively quenched, photon counting avalanche photodiode
Authors: Grayson T. P. , Wang L. J.
Published: February 2023

By careful attention to minimizing stray capacitance and inductance in the design of a circuit for passive quenching of an avalanche photodiode and suitable for counting single photons, we have succeeded in obtaining a time resolution of about 400 ps. This was measured by a deconvolution method with the help of a pulsed diode laser, an auxiliary PIN diode photodetector, and a time-to-digital converter, all of which have sub-nanosecond time resolution.
Up-conversion dynamics of doubly excited Er3+–vacancy–Er3+ centers in CsMX3 crystals
Authors: McPherson Gary L. , Gharavi Ali
Published: February 2023

Typical of trivalent impurities, Er3+ ions have a strong tendency to enter crystals of CsMgCI3, CsMgBr3 and CsCdBr3 in pairs to form Er3+–vacancy–Er3+ centers. A strong visible to UV up-conversion luminescence is observed from Er3+ containing crystals when the 4S3/2(E) excited state is pumped by a pulsed laser (545 nm–550 nm). The upconversion emissions arise primarily from doubly excited Er3+–vacancy–Er3+ centers via the pathway shown below.
Principle and applications of multiphoton pumped upconverted lasers (MU-lasers)
Authors: Mukherjee Anadi
Published: February 2023

Numerous commercial applications exist for compact, lightweight, inexpensive, coherent light sources in the entire visible spectrum. Diode lasers are used for SHG in cavities or for multiple photon pumping of rare earth ion doped solid state materials involving single photon absorption. To my knowledge, this is the first report on pure multiphoton pumped upconverted lasers called MU-lasers. The low absorption cross section of multiphoton interaction is compensated by a suitable propagation of the pump beam through low loss dye doped polymer waveguides, allowing long propagation lengths with high intensities for efficient conversion. Two photon absorption of an IR (740 nm) beam in certain dye doped polymer waveguides produce upconverted light centered at ~572 nm with a bandwidth of ~80 nm. A probable model is an efficient excited state energy transfer (S2 → T2) and subsequent upconverted fluorescence from T2 →T1′ although excited state complex formations cannot be ruled out. Waveguide lasers for upconverting diode laser wavelengths, integrated ultrafast visible lasers, and visible displays are some of the typical application areas.