bluuebunny/crossref_metadata_2025 huggingface dataset:
Validation of Stratospheric Ozone Observed by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment During 1992
Authors: Abrams M. C. , Gunson M. R. , Chang A. Y. , Rinsland C. P. , Zander R. , Newchurch M. H.
Published: February 2023

Measurements of stratospheric ozone were made by the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment from onboard the Space Shuttle during the period 8-16 April 1992. The precision and accuracy of the measurements are discussed in the context of establishing the accuracy and compatibility of the measurements relative to other space-based measurements of ozone. Coincident measurements were obtained from the Stratospheric Aerosol and Gas Experiment (SAGE) II instrument onboard the Earth Radiation Budget Satellite (ERBS) and three instruments, the Microwave Limb Sounder (MLS), the Cryogenic Limb Array Etalon Spectrometer (CLAES), the Halogen Occultation Experiment (HALOE) onboard the Upper Atmospheric Research Satellite (UARS). Three of the instruments, ATMOS, SAGE-II and MLS are demonstrated to be consistent to within ±10% over the altitude range between 100 hPa and 0.5 hPa (approximately 20 to 60 km), with ATMOS and MLS displaying a zero mean bias and a root mean square deviation (rms) of 3% and SAGE-II displaying an essentially systematic bias of -5% over the majority of the altitude range, except for below 30 hPa where SAGE-II displays a large positive systematic bias due to the effect of the aerosol attenuation resulting from the Mt. Pinatubo volcanic eruption in 1991. The comparison with HALOE indicates that ozone levels observed by ATMOS are systematically higher than HALOE by 5 to 25% with a clear gradient in the differences; in contrast the comparison with CLAES displays differences of as much as ± 30% with no obvious systematic scaling possible. Comparisons are evaluated in two separate schemes, by geographical coincidence and through zonal averages which illustrate the limitations of both schemes. Latitudinal and longitudinal variation are used to assess the sensitivity of the ATMOS measurements and to confirm the precision and accuracy, which should be less than 4% and 10% respectively.
Alexandrite Laser Injection-Seeded by an External Cavity Laser Diode for Airborne Water Vapor DIAL Measurements
Authors: Chyba Thomas H. , Ponsardin Patrick , Browell Edward V.
Published: February 2023

In the DIAL technique, the water vapor concentration profile is determined by analyzing the lidar backscatter signals for laser wavelengths tuned "on" and "off" a water vapor absorption line. Desired characteristics of the on-line transmitted laser beam include: pulse energy ≥100 mJ, high-resolution, continuous tuning capability (uncertainty < 0.25 pm), good spectral stability (jitter <0.5 pm about the mean), and high spectral purity (>99%).1The off-line laser, whose spectral requirements are much less stringent, is generally detuned less than 100 pm away from the water vapor line.
Geo-Stationary Imaging of Atmospheric CO and CH4 Distributions: Instrument Concept
Authors: Sachse Glen W. , Pougatchev Nikita S. , Hess Robert V. , Little Alan D. , Rinsland Pamela L. , Neil Doreen O.
Published: February 2023

Satellite sensing of the troposphere is an increasingly important issue as the need to understand man's impact on the atmosphere and the political pressure to further regulate gas emissions heightens. However, remote sensing of the troposphere and interpretation of such observations are challenging tasks. The nature of the troposphere with its "point" and distributed gas source regions (of natural and anthropogenic origin), complicated transport processes, and complex photochemistry results in large spatial and temporal variability. Thus our understanding of the troposphere would be greatly enhanced with remote observations that simultaneously achieve high spatial and temporal resolution. Although low earth orbit (LEO) sensors can achieve high spatial resolution (<50 × 50km), their temporal resolution (1 day or more) handicaps the investigation of important processes having time scales on the order of hours. The "global picture" afforded by a LEO sensor (even one that revisits the same spot on earth every 24 hours) is a convolution of the true but rapidly changing tropospheric "picture" with the highly restricted time/space view afforded by the LEO sensor. This viewing perspective further complicates the interpretation of the already complex troposphere.
Absorption and Scattering in Nonlinear Optical Polymeric Systems
Authors: Skumanich A. , Jurich M. , Swalen J. D.
Published: February 2023

Nonlinear organic systems often consist of a polymer matrix with a optical chromophore as a guest or an attached side chain. For enhanced optical nonlinearity, the chromophore absorption band should be located near the desired operating wavelength, but with no absorption. Good optical transmission is critical, and both the absorption and the scattering need to be minimized. Since the films are usually thin and weakly absorbing, it is difficult to determine either of these two material properties. By using the highly sensitive absorption technique of photothermal deflection spectroscopy (PDS), it is possible to obtain the fundamental optical spectrum of the nonlinear optical (NLO) systems over a wide energy range, and separate the absorption from the scattering. With this information, one can then select optimal polymer-chromophore systems. The absorption data indicates what the intrinsic waveguide loss should be for any given wavelength. For materials with low absorption, if there is high waveguide loss, either improved processing is necessary to lower the scattering, or insertion losses need to be reduced.
Polar Order and Relaxation of Second Order Nonlinear Optical Susceptibility in Amorphous Polymer Films
Authors: Wang C. H. , Gu S. H. , Guan H. W.
Published: February 2023

Second harmonic intensities of several polymer films containing nonlinear optical chromophores have been investigated as a function of NLO Chromophore concentration, temperature and poling field strength.
All-Optical Switching in a Single-mode Polymer Optical Fiber
Authors: Garvey D.W. , Kuzyk M.G. , Kruhlak R. , Dirk C.W. , Martinez S. , Selnau H. , Craig P. , Green L.
Published: February 2023

Motivated by the demonstration of all optical switching in a silica glass fiber, we are investigating the use of dye-doped polymer optical fiber as the switching medium. Because of the dye’s larger nonlinear response, devices in the 1 meter length range are possible. Measurements of the intensity dependent phase shift in these fibers are already within an order of magnitude of providing a π phase shift. In this contribution we report on the switching characteristics of a first generation Sagnac switch.
Third-Order Nonlinear Optical Effects in Organic Nickel Complexes and Triarylmethyl Cations
Authors: Greve Daniel R. , Geisler Tommy , Bjørnholm Thomas , Petersen Jan C.
Published: February 2023

The second molecular hyperpolarizability, γ, has been determined at 1064 nm by Third- Harmonic Generation (THG) using the Maker fringe technique, for a family of triarylmethyl cations and for a familiy of organic Nickel complexes as guests in PMMA thin films. For the metal complexes it is a well established notion that the low-lying transition with ligand to metal charge transfer character is important for the nonlinear optical properties(1). However, ambiguity arises due to large discrepancies between different measurements(2-5), as well as difficulties in assessing the exact contribution to γ of the ligand to metal charge transfer transition(2,6). To assess the latter question by experimental means, we present here a comparison between a family of Nickel complexes, and triarylmethyl cations. The electronic structure of the triarylmethyl cations resemble that of the metal complexes in the sense that intramolecular charge transfer from the periphery to the central atom takes place upon excitation in the first electronic band. This is shown by semi-empirical PM3 calculations on the three members of the family shown in figure 1. For the amino substituted compound 1 the calculations reveal a significant charge transfer from the amino moiety to the central carbon atom. For the molecules 2 and 3 this effect decreases due to the less efficient donor substituents (2) or forced planarity (3) resulting in more delocalized electronic states both in the HOMO and the LUMO. The observed γ values (table 1) can be correlated with the PM3 calculations in the way that the greater the amount of charge moved and the longer the spatial distance over wich it is moved, the greater is γ. The calculated static γ values, using the semi-empirical PM3/Finite-Field method follow the same trend although much smaller values are obtained.
Polarized Electroluminescence in Liquid Crystalline Main Chain Polymers Containing Arylene Vinylene Units
Authors: Festag R. , Greiner A. , Lüssem G. , Schmidt C. , Stümpflen V. , Wendorff J.H.
Published: February 2023

Polymers carrying arylene vinylene units have recently met with great interest because of their potential use in light emitting diodes (LED). This contribution is concerned with the combination of the electroluminescence properties characteristic of arylene vinylene polymers with the peculiar order characteristic of the liquid crystalline state within one material. New possibilities for manufacturing and applications of such materials are envisioned to result. The concept is to exploit the self-organization taking place in liquid crystalline material and the strong coupling of the orientational order to substrate effects and external fields in order to control the state of orientation of the chromophores and thus the polarization of the emitted light as well as its spatial distribution. The arylene vinylene units are incorporated for this end into a chain backbone and they are separated along the backbone by flexible spacers. Such polymers can be expected to display a glassy state, good processing characteristics and a long term stability of films manufactured from it. Such films are not necessarily liquid crystalline and soluble.
High Performance Chromophores and Polymers for E-O Applications
Authors: Jen Alex K-Y. , Rao Varanasi Pushkara , Chen Tian-An , Cai Yongming , Drost Kevin J. , Liu Yue-Jin , Kenney J. T. , Mininni Robert M. , Bedworth Peter V. , Marder Seth R. , Dalton Larry
Published: February 2023

Although tricyanovinylated thiophene derivatives have been demonstrated to possess large molecular nonlinearities, their use in practical electro-optic devices utilizing high temperature processing conditions is somewhat limited by the low thermal stability (Td ≈ 250 °C) of the tricyanovinyl group. Furthermore, the tricyanovinyl group is very sensitive to many polar solvents which are commonly employed in the curing and processing of polyimide based electro-optic materials. For this reason, we modified some of the highly active tricyanovinyl derivatives with the objective of achieving tradeoffs among many useful properties such as thermal stability, molecular nonlinearity, and stability to solvent and acid-base environments.
Liquid Crystalline Polymer Based Optical Data Storage
Authors: Maaskant Nico
Published: February 2023

Still some 90% of all information is stored on paper. But, the storage and distribution of information in an "electronic" format is rapidly growing and will play an ever increasing important role in the way our society will cover its information needs.
Application of the Dirichlet Principle to the Design of Progressive-Addition Lenses
Authors: Winthrop J. T. , Smith S. W.
Published: February 2023

The obvious purpose of an ophthalmic multifocal is to enable the wearer to see clearly at a multiplicity of viewing distances. Bifocals and trifocals accomplish the task admirably, but introduce discontinuities of power and prism into the visual field. Progressive-addition lenses offer distinct optical advantages over conventional multifocals: they provide clear vision at all viewing distances as well as continuity of the visual field. But for maximum visual comfort, the inherent aberrations of the progressive surfaces of these lenses must be minimized and the flow of surface power must be smooth. The present paper addresses the mathematical problem of smoothness and shows how the degree smoothness of the progressive surface can be optimized using the Dirichlet principle.1
Retinal Imaging
Authors: Webb Robert H.
Published: February 2023

Retinal imaging is a highly specialized form of microscopy. The microscope objective is the subject's lens and cornea, not what any microscopist would choose. The working distance is fixed at about 20 mm, and the object is shielded from any light except what comes through the objective or (in rare cases) through the eyeball from "behind". As the objective's numerical aperture (NA) increases, the resolution goes through maximum and quickly gets worse. Unless the response is medically inhibited, the NA decreases dramatically whenever enough light is introduced to see the object. .And the object itself is nearly transparent, always in motion and susceptible to damage from too much light.
AUTOMATIC REFRACTOR DESIGNS CURRENTLY IN USE: FIVE APPROACHES
Authors: Campbell Charles
Published: February 2023

Automatic infrared eye refractors have their beginnings in the work of Geoffrey Collins in the late 1930's but truly can be said to become an area of active development in the 1960's starting with the work of Campbell and Robson. There have been many ways invented to perform the basic refraction task of which a certain fraction have been used in commercial products.
Aberrations and Accommodation Limit the Field of View of Magnifiers
Authors: Katz Milton , Zikos George
Published: February 2023

An often heard comment by practitioners who prescribe magnifiers is that ultimately the patient decides whether a magnifier is good. Implicit in this comment is that the practitioner thought a given magnifier was good, after all why else try it, but the patient rejected it. This paper is an attempt to offer an explanation for this incongruity. It is premised on the difference in amplitude of accommodation between the patient and the practitioner, particularly if the practitioner is young.
Analysis of the Stiles-Crawford effect: the visual effects of cone acceptance angle, cone disarray, and retinal scatter
Authors: MacLeod Donald I. A.
Published: February 2023

The directional sensitivity of the retina is the joint result of many interacting factors, including the angular tuning of individual cones, the variation in tilt among different cones, and the scattering of light in the inner layers of the retina en route to the cones. Cone disarray and retinal scatter degrade the absolute sensitivity of the retina as well as broadening the Stiles-Crawford effect. Optical and psycho-physical sources of evidence are reviewed which suggest that retinal scatter and cone disarray, though measurable and functionally significant in many contexts, are not sufficient to make the normal distribution of visual sensitivity over the pupil much broader than is implied by the angular tuning of individual cones.
Investigation of Thermal Contact by the Photoacoustic Effect
Authors: Parpal Jean-Luc , Monchalin Jean-Pierre , Bertrand Lionel , Gagne Jean-Marie
Published: February 2023

We are studying the application of the photoacoustic effect to the measurement of small concentrations of aerosols deposited on a surface. Our investigation has been essentially focused on the detection of asbestos (chrysotile) fibers collected on a membrane filter. Detection is made possible by a sharp absorption band of the mineral at 2.7 μm and is improved by fiber alignment. The smallness of the fiber diameters with respect to the wavelength insures that the heat source generated by infrared absorption, is proportional to the mass of collected dust. However, the proportionality between the observed photoacoustic signal and the mass may be affected by the dependence of heat transfer to the subtrate upon deposition conditions. This effect is rather difficult to investigate with a low concentration of collected dust and a cell of minimum volume required for convenient detection: when the frequency of modulation is varied, interfering effects, such as another weak absorption or heat diffusion to the cell walls, are likely to complicate the interpretation. Therefore, we have used a very different set-up which is described below. We have also oriented our investigation towards the general study of the effect on the photoacoustic signal of an imperfect thermal contact between a thermally thin sample and its substrate. Results obviously can be applied to the understanding of the detection of collected aerosols, but also to other problems such as non-destructive adherence testing.
Practical Aspects of Chemical Studies of Powders by Photoacoustic Spectroscopy
Authors: Kinney John B. , Staley Ralph H.
Published: February 2023

Experience using photoacoustic spectroscopy to study chemical systems such as catalyst powders suggests a number of practical points to be considered in designing equipment and experiments. Cell design, gas atmosphere, temperature, pressure, and the sample are among the factors affecting the sensitivity and quality of spectra. Ultraviolet, visible, and near-infrared spectra have been obtained using a Princeton Applied Research Model 6001 Photoacoustic Spectrometer. For the mid-infrared region a Nicolet Model 7199 Fourier Transform Infrared Spectrometer has been used. Samples studied have included molecules adsorbed on platinum or silver supported on high surface area silica or alumina powders (or pellets), organic and organometallic molecules on silica and alumina powders, polymer foams, coals, oil shale, tissue samples, and others.
Number fluctuation laser velocimetry with multi-aperture
Authors: Ohbayashi K. , Iwamoto T. , Kanda T. , Ogita N.
Published: February 2023

The photon correlation function G(2)(τ) of scattered light from particles suspended in a solution is composed of three terms. By a suitable normalization it is written as where τ is the time interval and 〈N〉 the number of particles in the scattering volume. The first term on the right hand side is the dc-term, the second is the self-beat term, and the third is the number fluctuation term. Both the second and the third terms carry information of velocities of particles. We have weighted the second term by the factor η, which is η ≤ 1, to take into account the effect of the degree of coherence of scattered light. Laser doppler velocimetry and laser speckle velocimetry use the second self-beat term. For such purposes η is taken to close to unity and the number 〈N〉 is large. On the contrary, by reducing η and 〈N〉, the third number fluctuation term is relatively enhanced and can be used for velocimetry ; i.e. the number fluctuation laser velocimetry.
On-Board Correlator-Based Measurements of Particle Properties and Aircraft Velocity in the Upper Atmosphere
Authors: Smart Anthony E. , Abbiss John B.
Published: February 2023

The Titan Spectron Airborne Laser Transit Anemometer1,2,3based on measurements of particle transit time between pairs of sheets, was designed to determine the relative velocity vector between an airborne vehicle and its surrounding medium. Measurements in the upper atmosphere from a NASA F-104 aircraft suggest that the instrument can also estimate the size distribution and concentration of atmospheric aerosol particles. The energy detected during transits of the sensing sheets by individual particles, together with current values of monitors originally intended for diagnostics and performance logging permits an estimate of the radius of each particle under well defined assumptions which are discussed below. Signals from up to 900 particles per second can be individually reported to the aircraft 1553 bus, with properly sampled statistics where there are more than 900 /s. A distribution of particle radius and an estimate of concentration may be derived from these data.
Photon Correlation Spectroscopy of Dark "Non-Transparent" Fluids
Authors: Yudin I.K. , Anisimov M.A. , Dmitrieva I.A.
Published: February 2023

Photon correlation spectroscopy (PCS) is the most precise and accurate method to measure a size of submicron particles in transparent suspensions. However, interpretation is simple only for single scattering approximation and much more complicated for multiple scattering. For dark "non-transparent" media, such as a crude oil, metal powder suspensions, etc… PCS technigue is practically not usable. In such media the multiple scattering is negligible due to the strong light absorption. Low-optical-path cells are not convenient in practice. We propose modified light scattering geometry for particle size measurements in dark "non-transparent" fluids. In this geometry the scattered light is collected from the laser-beam input region. A rectangular sample cell is placed at angle 45° with respect to the incident laser beam. An optical axis of the photomultiplier is normal to the front plane of the cell. This optical geometry is simple for adjusting, and the stray light can be easily eliminated. Photon-correlation spectrometer and 8-bit multi-channel single-board correlator designed in our laboratory is used. Calibration experiments have been performed using water solution of black aniline dye, concentration of dye being widely varied. For maximum dye concentration a laser-beam penetration into the fluid is about 0,5 mm. At low dye concentration both the traditional light scattering geometry and the new one have been used. At all studied concentrations the measured dye-particle size is constant within experimental errors. A number of physical studies have been carried out using the proposed method: colloidal properties of crude oils and asphalten solutions, oil-water emulsions and motor oils.
High-Resolution Enhancement of DLS Results for Mostly-Submicron Colloidal Suspensions by Simultaneous SPOS Analysis
Authors: Nicoli D.F. , Hasapidis K. , McKenzie D.C. , Wu J.S. , Chang Y.J.
Published: February 2023

Improved characterization of particle size distributions (PSDs) of mostly-submicron suspensions is critical for optimizing production process parameters and determining overall quality for a wide variety of emulsions and suspensions. This paper describes a novel approach for PSD determination, offering significant improvements in resolution and accuracy over existing techniques, based on a combination of two proven techniques: dynamic light scattering (DLS) and single-particle optical sensing (SPOS). The DLS technique is effective when the majority of particles is smaller than 0.5-1 micron (urn), while the SPOS technique responds optimally to particles larger than this size. These two techniques, while radically different in principle and type of output, naturally complement each other.
Practical considerations
Authors: Brown Robert G W , Moir Christopher , Smart Anthony E
Published: February 2023

As with common sense, the practical considerations preceding any successful experiment are obvious in retrospect. Photon correlation experiments particularly demand an understanding and assurance of many features which may be taken for granted in simpler and less demanding applications. A major danger is that of sub-optimisation where one achieves flawless performance in the areas one knows about and somehow the less well understood areas receive less attention. To obtain the best from any experiment, every part of the sensing system and its interface with the measured phenomenon and the observer merits attention.
Introduction to Photon Correlation Techniques and Applications
Authors: Schätzel Klaus
Published: February 2023

Dynamic light scattering experiments on colloidal particles or similar systems typically use one of two optical systems which have been termed homodyne and heterodyne setups, respectively. The homodyne system uses a single illuminating laser beam. Light from the measurement volume is detected coherently, i. e. through a small detector aperture. As a result, fluctuating interference or light beats are observed due to relative motion of the scattering centers with respect to each other. For noninteracting particles, the coherence time of the detected light readily yields the coefficient of diffusion and hence the particle sizes - today the most important application of dynamic light scattering.
In-Cylinder LDA Measurements Using a Correlator
Authors: Max E. , Denbratt I.
Published: February 2023

An LDA system using photon correlation technique and capable of handling non photon resolved signals is reported. Comparisons with the power spectrum of actual detector signals show that the correlation technique is very efficient.

Turbulence production by means of swirl has been tested by making cycle resolved LDA measurements in a motored petrol engine for three different swirl levels. Firing tests of the engine show that the ignition delay (0 - 1% burned) correlates well with the high frequency components (> 1 kHz) of the turbulence at the spark plug location.
New high-speed Optoelectronic and electron superlattice and heterojunction devices
Authors: Capasso Federico
Published: February 2023

In this talk very recent advances in heterojunction and superlattice structures for high-speed optoelectronic and electron device applications are discussed.
Quantum Transport Calculation of Resonant-Tunneling Response Time
Authors: Frensley William R.
Published: February 2023

A form of quantum transport theory has been developed to model the resonant-tunneling diode and similar devices. The internal state of the device is represented by the Wigner distribution function. The boundary conditions applied to the Wigner function model the open-system nature of the device by coupling it to electron reservoirs. This coupling introduces irreversibility into the model, permitting meaningful calculations of the transient response.
Advances in Bipolar IC Technology
Authors: Tang D. D. , Ning T.H.
Published: February 2023

Si bipolar transistors and integrated circuits are widely used for high-performance gate arrays and high-speed cache, memories, and have since become the backbone of the high speed computers. In recent years, steady improvements in the understanding of the design and scaling of the small dimension bipolar transistors together with the advances in the process technology have led to the realization of ever faster bipolar transistors and circuits.
Millimeter-Wave Intergrated Circuits
Authors: Spielman Barry E.
Published: February 2023

The opportunities offered by monolithic millimeter-wave technology span radar, communications, electronic warfare, and missile seekers. These opportunities relate to size, weight, and cost reduction advantages over standard metal waveguide and hybrid integrated circuit implementations. However, specific technical challenges remain in realizing some important circuit building blocks.
Fast All Optical Switching in a Silicon on Sapphire Waveguide
Authors: Chelli H. , Niepceron A. , Paraire N. , Koster A. , Sauer H. , Carton M. , Laval S.
Published: February 2023

Using the excitation by a pulsed laser beam of a guided mode in a nonlinear silicon film deposited on sapphire, fast switching and bistability have been observed. A theoretical study, taking into account both electronic and thermal refractive index variations is presented which describes the experimental results accurately.
Traveling-Wave Semiconductor Laser Amplifiers for Simultaneous Amplification and Detection: Systems Experiments
Authors: Gustavsson Mats , Thylén Lars , Djupsjöbacka Anders , Karlsson Anders
Published: February 2023

We present results on systems experiments on a near travelling wave semiconductor laser amplifier used simultaneously for amplification and detection of optical signals. Bit error rate as well as bandwidth measurements are reported.
Systems Experiments with a Packaged 4x4 Polarization-Independent Switch Matrix
Authors: Granestrand Per , Thylén Lars , Stoltz Björn , Falk Jan-Erik
Published: February 2023

We report systems experiments involving transmission of 2 Gb/s signals through a 4x4 polarization independent switch matrix. Influence of crosstalk on bit error rate is investigated.
Progress towards demonstrating the viability of the synchronous multifrequency optical network (SYMFONET) for computer- and telecoms-distributed switching systems
Authors: Kirby P. A.
Published: February 2023

The SYMFONET concept allows practical fixed-wavelength distributed-feedback laser transmitters and multichannel-grating demultiplexer receivers to be used to form a passive optical-star network with ultra-high-capacity (10-100 Gb/s) and extremely low-latency switching of packetized data. This talk reports on progress at STC towards demonstrating the key component and system aspects.
Multiplexed Holographic Tunable Resonators for Reconfigurable Optical Interconnects
Authors: Strzelecki Eva M. , Lin Freddie
Published: February 2023

The benefits of using optics for massively parallel interconnects between electronic processors are well known. Additional flexibility can be achieved if optical switches are used to create reconfigurable optical interconnects. The enhanced efficiency of holograms placed in optical resonators has been proposed for the use in passive interconnects [1,2], for active devices [3], and for dense wavelength division multiplexing [4]. If a diffraction grating is placed inside a resonator, such as a Fabry-Perot resonator, its interaction length, and consequently its efficiency, can be significantly increased because of multiple paths of the optical beam inside a cavity in resonance. As a result, a combination of the characteristics of diffraction gratings and optical resonators is achieved: the direction of light can be changed and the efficiency of the diffracted beam exhibits peaks similar to that of a Fabry-Perot resonator. If the cavity can be tuned, the features of resonated holograms can be utilized for switching of light beams in optical interconnects. However, optical resonators pose great fabrication difficulties primarily due to stringent alignment requirements. We propose and demonstrate holographically recorded tunable Fabry-Perot resonators for the use in this optical interconnect configuration. Simultaneous recording of two high efficiency reflection gratings, which replace regular mirrors, removes the alignment problems. In addition, the use of volume holographic materials with refractive index modulation allows recording of multiplexed gratings to create multiple mirror resonators in a compact form which results in a much higher effective efficiency of the resonated grating.
The investigation of LiNbO3 crystal surface properties
Authors: Hovsepyan R.K. , Rilova V.Yu.
Published: February 2023

Lithium niohkte crystals are widely used in nonlinear and integrated optics, light modulators, radiation detectors. Hence, it is interesting to research a surface conduction and crystal-metal contact effect, as well as surface influence on crystal space property.
Dynamic Holography Effects in Ferroelectrics Induced by Spatially-Oscillating Photovoltaic Currents
Authors: Sturman B.I.
Published: February 2023

It’s well known that the main mechanisms of holographic grating formation in photorefractive crystals are the diffusion of carriers, their drift in the electric field, and the photovoltaic effect (PVE). We shall concentrate on the last mechanism. It’s often supposed that the PVE in ferroelectrics can be characterized by the current along the polar
c→-axis, j=α G I, where α is the absorption coefficient, G: the Glass coefficient, I: the light intensity. In this case, the PVE effect is analogous to the effect of supplementary electric field E
ph
=j(σ
d
+σ
ph
)−
1
, where σ
d
, σ
ph
are dark- and photoconductivity. The photoinduced field E
ph
reaohes 10
5
v/cm in LiNbO3 and LiTaO3. However, the effect of the PVE does not come to longitudinal current.
Holographic Currents and Non-steady-state Photo-emf in Cubic Photorefractive Crystals
Authors: Stepanov S. , Petrov M.P. , Sokolov I.A. , Trovimov G.S.
Published: February 2023

The transient and steady-state photo-emf in crystals having ambipolar photoconductivity is discussed. We present applications to impurity concentration determination and characteristics of photocarriers (sign, average lifetime and diffusion length)
Self-Pumped Phase Conjugation in Barium Titanate with High Intensity Nanosecond Pulses
Authors: Damzen M.J. , Barry N.
Published: February 2023

An investigation of self-pumped phase conjugation in barium titanate is made using nanosecond pulses (15 ns) derived from a repetitively pulsed (10 Hz) and frequency-doubled Nd:YAG laser system (532 nm wavelength). It is experimentally shown that high reflectivity (> 20 %) can be achieved. It is also shown that there is a progressive decrease in the reflectivity of both the corner-pumped and ring-passive geometries at pulse intensities of > 4 MW/cm2. At these intensity levels a high photo-carrier population is induced, altering the relative concentrations of Fe2+ and Fe3+ centres and leading to a strong intensity-dependent competition between hole and electron photoconductivity.
Photorefractive Parametric Interaction of Volume and Leaky Optical Waves in Planar Waveguide on Lithium Niobate
Authors: Shandarov V. M.
Published: February 2023

In optical waveguides with high photorefractive sensitivity the frequency - degenerate four - wave interactions are observed as well as in optical nonlinear materials [1], Several types of interactions nonanalogous for the processes in volume materials, can be realized in optical waveguides because of specifics of their properties.
Diffraction Efficiency of Holograms Recorded on Photorefractive Crystals by Counterpropogating Beams
Authors: Gnatovsky A. W. , Pigida A. S. , Pryadko L. D. , Shpak M. T.
Published: February 2023

The conditions of optimum hologram recording by counterpropagating laser beams have been found for SBN, LiNbO3:Fe and orientation dependence for grating diffraction efficiency has been defined.
Generation of direct current through a photoconductive crystal by asymmetric ac Held
Authors: Dooghin A. V. , Miklyaev Yu. V. , Zel'dovich B. Ya
Published: February 2023

Stationary current may appeare during the recording with ac external field under the illumination by the static interference pattern, when temporal profile of electric field has an asymmetric form.
Improvement of Photorefractive Gain in CdTe for IR Applications
Authors: Bylsma R. B. , Glass A. M. , Olson D. H. , Bridenbaugh P. M.
Published: February 2023

Doping of CdTe with Ti impurities results in improved photorefractive sensitivity and enhanced gain in the 0.9 to 1.3-um spectral region.
Present and Future of Photonic Switching
Authors: Yasui Tadahiko , Uemura Aritomo
Published: February 2023

1. Prologue An FDM (Frequency Division Multiplexing) system is a very promising system in that it is only feasible by Photonics. It utilized enormous bandwidth of lightwave and is independent of transmission methods and bitrate. This system seems more suitable for the coming broadband age than ATM-based systems because in future they will provide us with an infrastructure for more flexible and lower cost telecommunication networks.
High-Capacity Photonic Space-Division Switching System
Authors: Sawano T. , Matsuda K. , Suzuki S. , Fujiwara M.
Published: February 2023

Photonic space-division (SD) switching systems are very promising for STM (Synchronous Transfer Modes) broadband switching systems which can provide high speed services such as TV (HDTV) phone and HDTV distribution. An experimental small-capacity (up to 32-line) photonic SD switching system [1] has been already demonstrated. From a viewpoint of practical use, however, further increase in capacity is required. In response to this need, we have developed a prototype high-capacity (up to 128-line) photonic SD switching system. This paper presents the architecture and performance evaluation of the developed photonic SD switching system.
A New Type Photon-Gated Photochemical Hole Burning by Two-Color-Sensitized Photoreaction
Authors: Horie Kazuyuki , Machida Shinjiro , Yamashita Takashi
Published: February 2023

Photochemical Hole Burning (PHB) has attracted considerable interest not only as a tool for high resolution spectroscopy of amorphous solid at low temperature but also as a possible means for freguency-domain high-density optical storage.1) Many recent investigations have been devoted to a photon-gated mechanism because it allows nondestructive readout in utilizing PHB for a practical optical memory system. The mechanisms of previously reported photon-gated PHB systems are two-step photoionization, photodecomposition, and photoinduced donor-acceptor electron transfer reactions.1)
Investigation of the effect of large x-ray fluences on multilayer structures
Authors: MacGowan B.J. , Mrowka S. , Barbee T. , Da Silva L.B. , Eder D.C. , Koch J.A. , Pan L. , Underwood J. , Young. P.E.
Published: February 2023

The use of multilayer mirrors in x-ray laser cavities is complicated by extremely intense optical and x-ray pulses that damage the multilayer mirror before it has done its job. The issue of damage of the mirror by x-ray emission from the plasma amplifier has been studied experimentally using short duration (500 psec) bursts of soft x-rays from a laser produced Au plasma. Different damage/failure mechanisms have been observed and identified for Mo/Si, MoSi2/Si, W/C, WC/C and Cr3C2/C multilayers and damage thresholds quantified. The effect of the x-ray flux on the peak mirror reflectivity together with the position and shape of the bandpass has been resolved both temporally and spec­trally. The shape of the bandpass has been fitted to solutions to the Fresnel equations for aperiodic stacks in order to infer the time history of the stack. Rapid diffusion of Mo into Si in Mo/Si multilayers has been observed to occur in time scales of order 70 psec.
Optimization of Growth Conditions of Vapor Deposited Mo/Si Multilayers
Authors: Stearns M. B. , Stearns D.G.
Published: February 2023

The dependence of the layer structure and interfaces of e-beam deposited Mo/Si multilayers (ML) on the growth conditions has been studied. The substrate temperature was varied over a range of 300-600°K at deposition rates of 1 and 3 Å/sec. The structure of the ML was determined using small-angle x-ray scattering, large-angle x-ray scattering, and cross-sectional high-resolution electron microscopy. The variation of the normal incidence reflectivity was measured as a function of soft x-ray wavelength using synchrotron radiation. We found that the ML structure has a strong dependence on the substrate temperature and a lesser dependence on the deposition rate. ML grown at a substrate temperature of 300°K have Mo layers composed of small crystallites and exhibit significant short wavelength roughness. The lateral extent of the Mo crystallites increases and the interfacial roughness decreases with increasing substrate temperature up to 525-550°K. We attribute the larger Mo crystallites, improved texture and suppression of columnar growth observed at higher substrate temperatures to the increased surface mobility of the adatoms. The optimum conditions to obtain smooth layers by e-beam deposition were found to be a substrate temperature of ~525°K and a deposition rate of ~1 Å/sec. Thus to a great extent the smaller adatom energies of e-beam deposition can be compensated for by increasing the substrate temperature. Above TS~575°K interdiffusion is observed to significantly degrade the ML structure.
X-ray Scattering Studies of Correlated Interface Roughness in Multilayers
Authors: Sinha S.K. , Sanyal M.K. , Satija S.K. , Majkrzak C.F. , Schuller I.K. , Homma H. , Falco C.M. , Engel B. N.
Published: February 2023

The specular and off-specular reflectivity of radiation from single surfaces possessing roughness has been extensively discussed both within the framework of the Born Approximation and the Distorted Wave Born Approximation (DWBA). The same ideas can be generalized to reflectivities from multilayer structures. An Interesting effect arises due to the fact that the interface fluctuations between layers are usually highly correlated. This is shown to lead to structure in the off-specular reflectivity which mimics the structure found in the true specular reflectivity (e.g., Bragg peaks, etc.). In fact, such structure can persist due to interlayer height correlations for qz values where the true specular Bragg peaks have vanished due to large global roughness.
Multilayer Structures in Synchrotron Radiation Research and other Applications
Authors: Underwood James H.
Published: February 2023

We review multilayer EUV/x-ray reflector applications in SR and other instrumentation, and how, conversely, these are being used to provide insight into multilayer physics and chemistry.
Deconvolution of energy-dispersive reflection data using the Maximum Entropy Principle
Authors: Joensen K. D. , Gorenstein P. , Høghøj P. , Steenstrup S.
Published: February 2023

At the previous OSA meeting on X-ray multilayers P. Dhez described using a white-beam, fixed-angle, solid-state detector experiment (the so called energy-dispersive setup) for easy characterization of multilayer structures. The simplicity of the setup makes it ideal for in-situ analysis and hard x-ray reflectivity measurements. The multilayer d-spacings can be readily obtained using only the spectrum of the reflected beam, and the absolute reflectivities can be obtained using both the white-beam spectrum and the reflected spectrum. The simplicity of the setup makes it ideal for in-situ analysis and hard x-ray reflectivity measurements. The multilayer d-spacings can be readily obtained using only the spectrum of the reflected beam, and the absolute reflectivities can be obtained using both the white-beam spectrum and the reflected spectrum. Figure 1 shows an example of a observed white-beam spectrum consisting of Bremsstralung and superimposed W-fluorescence lines. Figure 2 shows an example of the observed spectrum after reflection with a multilayered supermirror structure (described elsewhere in these proceedings).
X-Ray Investigations of Supersmooth Surfaces, Near Surface Layers and Thin Films
Authors: Kozhevnikov I. V. , Alaudinov B. M. , Artyukov A. I. , Asadchikov V. E. , Bukreeva I. N. , Karabekov A. Yu. , Vinogradov A. V.
Published: February 2023

The potentialities, advantages, and perspectives of X-ray methods are considered for quantitative testing and examination of supersmooth substrates, near-surface transition layers of solids and thin films. The methods are based on analysis of X-ray scattering diagram and allow one to determine the power spectral density (PSD) of surface microroughness without a priori assumptions about the form of the correlation function of roughness heights or their probability density function.
ATTAINMENT OF PHASE EQUILBRIUM IN MULTILAYERS
Authors: Pershin Yu.P. , Bugaev E.A. , Kopilets I.A. , Yulin S.A. , Kozhevnikov I.V.
Published: February 2023

Structural, phase and chemical stabilities of multilayers Mo-Si, MOSi2- Si, W-Si, WSi2-Si, Cr-Sc, W-Sc, Mo-B4C, Mo−(B+C), Mo2B5-B4C, Cr3C2-C, TiC-C, Ti-Be and others were studied in 300-1100°C temperature range by small-angle and large-angle X-ray diffraction scattering and electron microscopy methods. The structural instability (crystallization of amorphous Si, C, MOSi2, WSi2, MoC, MoB2, Mo2B5, B and Cr3 C2 and recrystal-lization of polycrystal Mo, W, Sc, MoSi2, WSi2, Mo2B5 and MoC layers) as well as the phase instability (transformation of MoSi2 lattice from hexagonal to tetragonal modification) are responsible for the degradation of multilayers due to the development of the interface roughness and mechanical stresses. The chemical instability (formation of MoSi2 and WSi2 silicides at interfaces of Mo-Si and W-Si multilayers, Mo2C and MoC carbides and MoB2 and Mo2B5 borides in Mo-(B+C) multilayers, TiBe12 in Ti-Be ones) influences critically chemical composition profile, layer thicknesses and a period of multilayers. Formation of chemical compounds accompanied by an amorphization of polycrystal layers (growth of amorphous Mo2C and MoC carbides instead of polycrystal Mo at about 450 °C and the subsequent substitution of polycrystal molybdenum carbides on amorphous borides MoB2 and Mo2B5 at 700-800 °C in Mo-(B+C) multilayers) promotes the smoothening of interfaces. This effect of the chemical instability can be used for an improving of the X-ray reflectivity of multilayers.
The correlation between reflectance and surface roughness of multilayer X-ray optics
Authors: Windt D. L. , Waskiewicz W. K. , Griffith J.
Published: February 2023

High-efficiency, normal-incidence X-ray multilayer mirrors are now being used for a variety of practical applications. Among these is Extreme Ultraviolet (EUV) lithography. A practical EUV lithography printing tool may include as many as seven normal-incidence multilayer reflections, so it is imperative that the mirror substrates be fabricated with low surface roughness in order to achieve high reflectance, and consequently high system throughput (wafers/hour.) In order to develop the necessary techniques to fabricate such mirrors, it is first necessary to accurately quantify the surface finish requirements of the mirror substrates, and to then identify the surface finish metrology tools that can be used by the manufacturer during the substrate fabrication process. To this end, we have examined correlations between direct surface finish measurement techniques and normal-incidence, soft X-ray reflectance measurements of highly-polished X-ray multilayer mirrors.
Image Photon Counting Detectors
Authors: Papaliolios Costas
Published: February 2023

A comparison of four available detectors, the Boksenberg, the MAMA, the PAPA, and the resistive anode, point out the individual strengths and weakness.
Quantum-limited Imaging in Vision
Authors: Saleh Bahaa E. A.
Published: February 2023

The purpose of this paper is tow present an overview of current research in the area of vision under quantum-limited conditions. It is addressed to an audience of participants in research in the area of quantum limited imaging who are not necessarily familiar with the equally rich pool of research in quantum-limited vision.
Non-Classical Interference Effects in Optics
Authors: Mandel L.
Published: February 2023

Recent experiments in which two photons produced simultaneously in the process of down-conversion interfere will be reviewed.
Acceleration of Maximum-Likelihood Image-Restoration for Fluorescence Microscopy and Other Noncoherent Imagery
Authors: Holmes Timothy J.
Published: February 2023

In previous publications we presented an image-restoration algorithm for quantum-limited noncoherent imagery that is based on maximum-likelihood estimation [1]. This work was extended from the work of others in nuclear-medicine imaging [2,3]. A practical issue of using this method is in its speed of execution. This method is derived from the iterative expectation-maximization (EM) algorithm [4], and as such its convergence can be slow. We have observed this issue in our simulations as others have for positron-emission tomography [5].
Optimization of Photorefractive Polymers for Optical Processing
Authors: Meerholz K.
Published: February 2023

Photorefractive materials have many potential photonic applications, including dynamic holographic storage and image processing. Recently, the new class of amorphous organic photorefractive materials has emerged, offering wide structural flexibility, easy processability, and low cost at very high performance levels. Progress in this field has led to absorption-limited complete diffraction for the readout of a hologram stored in materials of only 100-150 μm thickness and to extremely large net gain coefficients of more than 200 cm−1 compared to 40-50 cm−1 in the best inorganic photorefractive crystals known to date. These excellent properties occur in materials with low glass transition temperatures and result from refractive index modulations as large as Δn ≈ 10-2, mostly originating from a Kerr-type orientational birefringence rather than the electro-optic effect as in traditional photorefractive crystals. The materials can be adjusted for photorefractivity over the entire visible spectrum and in the near infrared. The sensitivity is excellent enabling the use of low-power laser sources, such as HeNe laser or laser diodes.