bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear optical studies of adsorbates on silicon surfaces
Authors: Höfer U. , Heinz T. F. , Li Leping , Reider G. A.
Published: February 2023

Second-harmonic generation (SHG) provides a sensitive probe of the dynamics of adsorption on semiconductor surfaces. The technique has been applied to examine diffusion, desorption, and dissociation processes on silicon surfaces. Desorption has been investigated for hydrogen on Si(111)7×7 and Si(100)2×1 through isothermal measurements. The high sensitivity of SHG to adsorbed hydrogen allows us to perform such experiments at coverages well below 1% of a monolayer. For both surfaces, the results reveal a marked departure from the second-order kinetics expected for a recombinative desorption reaction. This observation is related to the details of the surface structure. Surface diffusion has been investigated by means of second-harmonic diffraction from a spatially modulated adsorbate density. For H/ Si(111)7×7, a diffusion barrier of 1.5 eV, ~50% of the H-Si binding energy, has been established. Such a high barrier for lateral motion stands in marked contrast to the usual behavior on metal surfaces. For NH3 and O2 on Si(111), SHG is found to be strongly dependent on the chemical state of these adsorbates, permitting real-time investigations of dissociation reactions.
Applications of Q-switched and cw diode pumped solid-state lasers
Authors: Cramer Larry
Published: February 2023

Commercial applications cover a diverse area from industrial, military, and medical applications. Diode pumped lasers have many advantages in applications. The diodes are compact, have low operating voltages, produce little heat, and have very long operating lifetimes. All of the advantages of laser diodes allow for development of reliable commercial products. Pumping a solid-state laser medium has several additional advantages. The multimode diode output can be converted efficiently into a TEM00 mode. The solid state medium can store energy, which can be released in a Q-switched pulse. The solid- state materials can be operated in wavelength regimes that laser diodes can not achieve, in both the visible and infrared regions. The industrial applications of micro-machining and marking materials both use a Q-switched laser. The high peak power pulses from the Q-switched laser allow for ablation of material off of a surface. Semiconductor memory repair is a specific example where the advantageous properties of diode pumping quickly replaced all other laser sources. Continuous- wave diode pumped lasers have industrial applications in the generation of F.T. Raman spectra, where it will become possible to monitor the production of chemicals for pharmaceuticals. Military applications of laser ranging require that a system be efficient, compact, and highly reliable. As diode pumped laser energies increase and more wavelength diversity is achieved, diode pumped lasers will replace much of the current technology. Bio-technology applications include the development of optical trapping microscopes, where cells and small particles can be manipulated by the force exerted by a laser. The effects of drugs on individual cells can be studied, and many other applications are just now being developed by using an optical trapping microscope. Diode pumped solid-state lasers have the mode quality and stability that allow for the development of commercial microscope systems.
Analysis of single aerosol particles by laser ionization mass spectrometry
Authors: Murphy Daniel , Thomson David
Published: February 2023

We have obtained mass spectra from single aerosol particles with diameters 0.5–10 μm. The signal-to-noise ratio exceeded 10,000 for the larger particles. In operation, aerosol particles cross a diode laser beam after entering a vacuum chamber. The resulting scattered light is used both to size the particles and to trigger a pulsed laser of sufficient power to form ions from the particles in a single shot. A time of flight mass spectrometer disperses the mass spectrum. Spectra have been obtained by using both infrared and ultraviolet pulsed laser sources. A future portable or airborne version of this instrument will add capabilities to the analysis of atmospheric aerosol particles.
Measuring visual performance as a function of pupil size in clinical populations
Authors: Applegate Raymond A.
Published: February 2023

The eye's pupil defines the area of each optical surface used to form the retinal image. Intervention (e.g., radial keratotomy, photorefractive keratectomy, displaced IOL) and/or pathology (e.g., corneal degeneration or scarring) can markedly change the optical properties of the eye and aggravate or improve visual performance as a function of pupil size. The following constraints make measurement of these properties difficult: 1) the use of an artificial pupil placed in front of the eye, as opposed to natural pupil plane; 2) selection and maintenance of a relevant reference axis; and 3) selection and quantification of a reasonable psychophysical task. We address these constraints by employing 1) a Maxwellian view system with a variable exit pupil diameter imaged in the plane of the eye's entrance pupil; 2) a Thibos foveal achromatic alignicator to define the reference axis; and 3) a high contrast Bailey-Lovie acuity chart and a fixed letter scoring criteria. Measurements on patients prior to and after radial keratotomy and photorefractive keratectomy demonstrate that best corrected visual acuity is generally decreased following intervention for large pupils and is generally unchanged for small pupils.
Use of scatterometry in photomask metrology
Authors: Gaspar Susan M. , Krukar Richard H. , Peterson Gary L. , Wilson Scott R. , MacNeil J. R. , Naqvi Sohail S. H.
Published: February 2023

The microelectronics industry has demonstrated the need for device structure characterization during photomask processing since the line quality on a lithographic mask is critical to the eventual device quality and reliability. Applying laser scatterometry as a characterization technique for measuring line edge roughness on photomasks partially fulfills this need. A novel, two dimensional scatterometer consisting of a frosted dome intercepts the scattered light from the illuminated sample. A CCD camera images the dome's surface, and the images are stored on a computer. A unique image combining algorithm was developed and implemented, increasing the dynamic range of the recorded scattered light image. In addition, a computer model was developed to create two dimensional diffraction grating images with line edge roughness. Taking the FFT of the image produced a simulation of the far field scatter pattern. A neural network was trained on a set of simulated grating scatter data. The neural network performed very well when verified against further simulated data with line edge roughness. Measurement of surface roughness on etched phase shifting masks (PSM) was performed by using angle resolved scatterometry. The power spectral density (PSD) function was obtained, and a rms roughness was calculated. Reactive ion etching (RIE) of quartz photomasks resulted in increased surface scatter rendering them unsuitable for PSM use. A comparison of surface roughness values is presented for reactive ion etched and neutral ion beam milled photomask surfaces.
Raman excited microwave spin echoes for optical data storage
Authors: Shahriar M. , Hemmer P. , Kim M.
Published: February 2023

There has been much recent interest in the use of optical photon echoes for information storage and processing. Unfortunately, existing optical echo memories require doped crystals at liquid He temperature. The proposed scheme uses an optically excited microwave spin echo to store optical temporal information in the Raman excited ground state coherences. The advantage is that microwave echoes are known to exist at room temperature with decay times approaching 1 s in certain materials. We show that these spin echoes can be excited and detected optically, thereby allowing storage densities that are comparable to the optical echo techniques. Briefly, a three level A system is used, which can be excited by two near resonant optical transitions or one near resonant microwave transition. The Raman interaction first stores temporal and phase information in an inhomogeneously broadened ground states coherence. A microwave π-pulse is used to time-reverse the coherences, thus generating spin echoes that can be detected optically by a Raman probe. Preliminary experimental results will also be reviewed.
Optoelectronic multi-chip modules
Authors: Jannson T. , Chen R. , Hirsh J.
Published: February 2023

A new concept of optic interconnects for multi-chip modules (MCMs) is proposed based on all-silicon integration of CMOS IC with single-mode integrated waveguides. This new concept, based on light distributed interconnect active (LIDIA) optoelectronic substrates, provides chip-to-chip direct communication within 0.35 μm VLSI/ULSI CMOS MCMs. In order to avoid direct integration of GaAs light sources into silicon circuitry, the CW laser diode array is located outside the MCM. The interconnect transceivers are composed of E-O external modulators and silicon photodetectors. The presented architecture requires only minor modification of silicon CMOS circuitry. In this communication, we analyze system design and technological bottlenecks of the optoelectronic MCMs based on CW LD array, single-mode channel waveguides, plasmon E-O modulators, Si photodetectors, and 0.35 μm CMOS MCMs.
Fabrication of electro-optic thin film channel waveguides using ion milling
Authors: Xu T. , Brueck S. J. R. , Wu A. Y.
Published: February 2023

Many methods have been proposed for etching ferroelectric thin film, such as PLZT and BaTiO3 for optical waveguide modulator applications, including wet chemical etching, chemical plasma etching, and reactive ion beam milling. In this paper, etching of the film with plasma by using pure argon is discussed and the experimental results on etching PLZT thin films are reported. Since a strictly physical process is involved during etching, because of the chemical inactivity between argon and thin film material, this etching process gives the advantage of preserving the stoichiometry of the thin film material. It turns out that the etching rate is lower than that of the chemical plasma etching, but a much better channel edge quality that is more suitable for optical waveguide applications is produced. SEM micrographs and optical waveguiding results will be presented. To address the issue of photoresist hardening problem during the long etching, a metal mask is used. The advantages and drawbacks of the etching method for fabrication channel waveguide modulators will be discussed.
Variable index zirconium oxyfluoride waveguides
Authors: Gibson Ursula J.
Published: February 2023

The use of an ion beam to create localized regions of higher refractive index presents the possibility of making planar integrated optic lenses and correcting the chromatic aberrations of holographic gratings. We have studied the use of ZrF
x
O
y
for these applications. Thin film waveguides of zirconium oxyfluoride were deposited by using thermal evaporation of zirconium fluoride with concurrent oxygen bombardment. The index of refraction of the films increases from ~1.5 to 1.9 with increasing levels of bombardment; somewhat increased waveguide losses are also observed. Localized regions with higher index and a planar surface have been made.
Tomography of cylindrical objects: a comparison of Abel, onion-peeling, and filtered back-projection methods
Authors: Dasch Cameron J.
Published: February 2023

The Abel, onion-peeling, and filtered back-projection inversion methods can be inter-compared without assumptions about the object being deconvolved. If the projection data (such as optical absorption, beam deflection, or phase shift) are taken at equally spaced radial positions, the deconvolved field is given by weighted sums of the projections divided by the data spacing. The weighting factors are independent of the data spacing. All the methods are highly similar and have Abel-like behavior: the field at a radial location is primarily determined by the weighted differences of a few projections around that radial position. The weighting factors also determine the relative noise of each method. Based on ease of calculation, robustness, and noise, a three-point Abel inversion is preferred. This analysis also shows that the signal-to-noise ratios of the deconvolutions deteriorate if the projection data are taken too close together.
Perceptual summation of image blur in the peripheral visual field
Authors: Geri George A. , Zeevi Yehoshua Y.
Published: February 2023

Summation thresholds were measured at 16° and 32° eccentricity in order to determine the spatial properties associated with the perception of blur in low-pass filtered images. Both real-world and sinusoidal images were processed by using one of a series of Gaussian integrating kernels whose variances differed. The images were either circular or annular and were centered at either 16° or 32°. Stimulus area was varied, although the annular stimuli were always 8° wide. The images were presented in pairs with one member of each pair being an unprocessed mirror image of the image under test. The data for both types of stimuli were qualitatively similar to each other and to those previously reported for foveally presented stimuli, in that blur threshold varied monotonically with spatial cut-off frequency. The data obtained for the annular stimuli were unlike those typically obtained with circular stimuli, however, in that they often showed a nonmonotonic relationship between threshold and stimulus area. A series of control studies eliminated edge effects and meridional anisotropies in form perception as explanations for the nonmonotonicities. It is concluded that the differences in the spatial summation of circular and annular stimuli reflect differences in the functional (and by implication, the cortical) representation of these two classes of stimuli.
Saturation of four-wave mixing signals in laser diodes
Authors: Simpson T. B. , Liu J. M.
Published: February 2023

Under very weak, nearly degenerate optical injection, laser diodes undergo amplitude and phase modulations that can be modeled by using the lumped-circuit rate equation approach. Population pulsations of the free carriers induce four-wave mixing between the injected optical field and the oscillating laser diode field. By measuring the amplitude modulation signal, regeneratively amplified input signal, and four-wave mixing signal, key diode parameters such as the carrier lifetime, relaxation resonance, and anti-guiding factor can be calculated. As the injection field is increased above this small signal regime the four-wave mixing signal saturates and broadens. Over certain detuning ranges, where the broadening is most pronounced, the nonlinear interaction can induce a longitudinal mode hop. Depending on the frequency difference between the injected optical field and the near-resonant laser mode, the laser diode will oscillate on one of the two longitudinal modes. Associated with this bistable operation is the appearance of a resonantly enhanced highly nondegenerate four-wave mixing signal on a third longitudinal mode.
Optical attenuation in ferroelectric thin film channel waveguides
Authors: Xu T. , Brueck A. J. R. , Wu S. Y.
Published: February 2023

We have attempted to measure the optical attenuation in ferroelectric and electro-optic thin film channel waveguides. Under the assumption that the scattering sites are homogeneous within the waveguide, we can trace the intensity variation inside the waveguide by measuring the intensity variation of the scattering. The measurement is carried out by using a thin fiber scanning along the waveguide to collect scattering. The fiber is held vertically and close to the waveguide surface, and the collected light is detected by PMT and then recorded by computer. The advantage of this method is that it avoids the coupling efficiency, which is hard to determine. The PLZT and BaTiO3 films are fabricated by using a rf sputtering technique, and channel waveguides about 6 to 20 µm in width are fabricated by using ion milling. The results are reported for both PLZT and BaTiO3 waveguides at 632 nm and 1064 nm.
Neural network applications to interpretation of optical chaos
Authors: Pethel S. D. , Bowden C. M. , Sung C. C.
Published: February 2023

Forward-feed, hidden-layer, neural network (FFNN) algorithms, with nonlinear thresholding functions, trained on a chaotic time series, are shown to constitute a global approximation to the chaotic phase space attractor. As a function generator, a FFNN, trained on an arbitrary chaotic time series, forms a functional realization of that time series, i.e., the FFNN can “learn” the underlying rules/equations that generate chaotic dynamics. We present results from several model calculations, including that for the single-mode laser, the Duffing oscillator, and the Ikeda model to demonstrate characterization, with respect to the phase space attractors, self-generation for effective data window extension of stationary time series, and multistep prediction commensurate with the associated Lyapunov critical component. In addition, we apply our new method of analysis to the study of stimulated Brillouin scattering (SBS) of light from a cw-pumped optical fiber. We use our FFNN method to clearly demarcate purely deterministic from purely stochastic contributions in the SBS temporal evolution by using signal generation from the standard stochastic SBS equations. Results are analyzed for regions of the parameter space and conditions that include those of corresponding reported experiments.
Holographic polaro-interferometer for studying long-scale-length plasmas
Authors: Fernandez J.C. , Guttmann G. D. , Gomez C.
Published: February 2023

Holographic polaro-interferometry represents a flexible tool for studying density and magnetic fields in an ICF plasma. The polarization and the changes in beam phase are recorded in a single hologram. By using the polarization information, the magnetic field (i.e., the Faraday rotation) of the plasma can be determined, while the density profile can be inferred from the change in beam phase. The experimental setup uses a Mach-Zender arrangement to form the hologram/interferogram. A single beam is passed through the plasma. This beam is split when entering the Mach-Zender arrangement. The reference beam will be passed through a spatial filter to erase phase information generated from the passage through the plasma. Polarized reference beams are generated after the reference beam is split and then passed through a polarizer. This diagnostic is being developed for application to ICF plasmas. It will be tested on a long-scale-length plasma generated by an exploding wire. Holographic polaro-interferograms will be presented.
A scanning reflectance laser-feedback interferometric microscope capable of nanometer-scale profile height measurements of surfaces
Authors: Wong Terrence L. , O'Neill Michael P. , Osborne Leslie C. , Richard Jenkin , Bearden Alan
Published: February 2023

Using laser feedback interferometry (LFI) in which the amplitude and phase of the retroreflected beam modulates the intensity of the laser, we have constructed a scanning reflection confocal microscope with a vertical resolution of ~1 nm and a lateral resolution exceeding that of other confocal microscopes. Images obtained with this microscope display contrast because of surface topography, coherent reflectivity, and object motion. Surface reflectivities as low as 10–6 and picometer amplitude vibrational motions are easily observed. In addition, because of the simplicity of LFI's configuration, alignment of the system is remarkably simple. Further studies include the possibility of higher lateral resolution by using superresolution methods, and characterization of photon weak-localization phenomena in amorphous materials.
Dynamic three-dimensional short-pulse propagation
Authors: Luther G.G. , Hart D.E. , Moloney J.V. , Wright E.M.
Published: February 2023

In an effort to understand the physics of three-dimensional short-pulse propagation in nonlinear materials, we have studied the following set of equations numerically: where

R
^

(

t
−
t
'

)

=

∫

−
∞

∞

(
α
(

Ω
)
+
i
δ
n
(
Ω
)
)

e

i
Ω

(

t
−
t
'

)

d
Ω

is the local linear response function of the medium and α(Ω) and δn(Ω) are, respectively, the experimentally measured linear absorption and linear index of refraction. In preliminary studies of these equations where the linear response term is approximated by the usual dispersion term,

∂

t
t

2

A

, it was found that the combination of normal dispersion and relaxation of the nonlinearity increase the threshold for collapse-like events by redistributing the pulse energy. Numerical studies of the full equations with spectral absorption and dispersion for water will be presented at the meeting.
Optimum focusing of Gaussian laser beams
Authors: Katz Joseph , Li Yajun
Published: February 2023

The optimum focusing of Gaussian laser beams was studied extensively on the basis of the maximum concentration of energy on a target. However, in many practical applications of laser beams requirements are different—emphasis is placed on the size and shape of the laser spot that is focused by a thin lens and illuminates a target located in a plane at a given distance. In this paper, variation of spot size is discussed and a criterion of minimization of spot size on a target is shown.
Reflection on nonlinear reflection
Authors: Shen Y. R.
Published: February 2023

The status of surface and interface studies by optical second harmonic and sum-frequency reflections will be reviewed. Selective examples will be used to illustrate the unique capabilities of the techniques.
Placement of L and M cones in the peripheral photoreceptor matrix
Authors: Cicerone Carol M. , Otake Shiro
Published: February 2023

The density of cones (Williams, 1988; Curcio, 1990, 1991) as well as the relative number of the different cone types (Otake and Cicerone, 1992) in the periphery of the human retina have recently been reported. The placement of individual L and M cones within the photoreceptor matrix at 17° temporal eccentricity is reported here. In this region the 3 min center-to-center spacing of the cones and robust optics have allowed the measurement of spectral sensitivities of single cones. After a rod bleach, a test (0.86 min) of varying wavelength was presented upon cone-isolating backgrounds (Cicerone and Nerger, 1989) in a grid of 1.5 min spacing. The locations of distinct peaks and troughs were replicated between sessions and under various adapting conditions. Spectral sensitivity measurements exclude the possibility that rods or S cones contribute to these determinations. We conclude that these are the locations of individual L and M cones within the receptor mosaic of the human peripheral retina.
Rotation invariant pattern recognition using a double coordinate transform
Authors: Asselin Daniel , Arsenault Henri H.
Published: February 2023

We use an optical rectangular-to-polar coordinate transformation system to accomplish rotation-invariant pattern recognition. The coordinate transforming device is a special computer-generated hologram. The output of the device is optically Fourier transformed, yielding a rotation-invariant output. However, the performance of the system is degraded by a wraparound effect due to the coordinate transformation. We show how the performance may be significantly improved by superimposing two coordinate transforms. The all-optical system includes the coordinate transforming device and a liquid-crystal light valve. At this time the final recognition is done by computer, but we will show how to incorporate this system into an all-optical invariant pattern recognition system.
Resonance ionization spectroscopy of the 3p Rydberg and B valence states of HCO and DCO
Authors: Cool Terrill A. , Song Xiao-Mei
Published: February 2023

Resonance two-photon ionization (R2PI) spectroscopy has been used for medium resolution studies of HCO and DCO. Vibronic analysis of subband positions for both A′ and A″ symmetry components of the 3p2Π Rydberg states of HCO and DCO yields values for the Renner-Teller parameter ε, dipolar coupling constant g
k
, quartic anharmonicity parameter g22, harmonic bending vibrational frequency ω2, anharmonicity constant x22, and spin-orbit splitting constant A. Values of the harmonic frequencies (ω
2
and anharmonicity constants x22 for the bending vibrations of the HCO and DCO

χ
˜

2

A
′

ground states are also determined. Term values, the three harmonic vibrational frequencies, and six anharmonicity constants are measured for the

B
˜

2

A
′

states of both molecules. Fundamental frequencies of 1382 cm−1 and 1213 cm−1 for HCO and DCO, respectively, are identified with the

B
˜

state bending vibration; frequencies of 2597 cm−1 for HCO and 1944 cm−1 for DCO correspond to CH (CD) stretching, while the lowest fundamental frequencies of 1066 cm−1 for HCO and 922 cm−1 for DCO correspond to the vibration of singly bonded C-O.
Electronic quenching and vibrational energy transfer in NO (A2∑+) from 300 to 4500 K
Authors: Gray J. A. , Durant J. L. , Paul P. H. , Thoman J. W.
Published: February 2023

We report rate coefficients for electronic quenching of NO (A
2
∑+) by N2, Ar, and NO (X
2
∏) measured at room temperature and behind incident and reflected shock waves (900 K to 4500 K). The N2 quenching cross-section increases dramatically from 0.007 Å2 at 296 K to 7 Å2 at 4500 K. Modeling based on an ion-pair intermediate for the collision accurately predicts the increase in N2 cross-section up to 2300 K and suggests that additional mechanisms become important at higher temperatures. We also use simultaneous measurements of dispersed fluorescence spectra and fluorescence decay rates from v' = 0 and v' = 1 to obtain vibrational energy transfer rates in A
2
∑+ at 1900 K.
Avalanche-enhanced self-electro-optic-effect device
Authors: Horbatuck Suzanne M. , Brown Thomas G.
Published: February 2023

The ability to enhance optical nonlinearities associated with the photogeneration of free carriers can be accomplished with carrier multiplication. The gain mechanism provided by carrier multiplication is inherently feasible in avalanche photodiodes. We present results from optical bistability experiments performed on silicon avalanche photodiodes under reverse bias conditions in the case of thermal nonlinearities (Joule heating) and electronic nonlinearities (free carrier plasma effects). The reflected intensity versus the operating voltage is measured at the input intensity of the diode, as is also the output photocurrent versus operating voltage; in both instances, the reflected signal or photocurrent are multivalued functions of the operating voltage. We label such a device as an avalanche-enhanced self-electro-optic-effect device or A-SEED.
Distortion invariant pattern recognition using the orthogonal Fourier–Mellin moments
Authors: Shen Lixin , Sheng Yunlong
Published: February 2023

Scale and rotation by invariant pattern recognition is achieved using the orthogonal Fourier–Mellin moments, Q
n
(r)exp(jmθ), where Q
n
(r) are the polynomials on r and are generated by orthogonalizing the set of powers {r0,r1,…, r
n
}. The Q
n
(r) are in fact the modified Zernike radial polynomials without the restrictions that the radial moment orders must be even and greater than the circular moment orders |m|. The orthogonal Fourier–Mellin moments may be also calculated in the Cartesian coordinate system as the modified complex moments without the restriction that the moments order p and q must be positive integers. The Zernike moments have been shown to have the best overall performance among the various image moments. The performance of the new moments for pattern recognition is compared with that of the Zernike moments in terms of image representation, class separability, and noise sensitivity as functions of the number of the total moment features and of the radial orders of the moments. Experimental results show that for a given class of objects the orthogonal Fourier–Mellin moments use features of much lower radial orders for image classification, so it is then less sensitive to noise.
Infrared wavelength multiplexed holographic storage in photorefractive LiNbO3
Authors: Catanzaro Brian , Ma Jian , Fainman Yeshaiahua , Lee Sing H.
Published: February 2023

Holographic optical storage in photorefractive LiNbO3 is important for parallel computing applications because of its large memory capacity. The practicality of memory systems will strongly rely on random access time and packagability. Advances in color tunable semiconductor lasers (SL's) may play an important role in holographic memory systems because SL's can be tuned in nanoseconds and packaged easily. However, they impose new requirements for holographic materials: sensitivity in the near infrared range and the ability to multiplex many images given a limited tuning range. To support such systems we have identified photorefractive specially doped LiNbO3 to provide high sensitivity in the SL range. The sensitivity of our crystals was evaluated experimentally for the range of 780 to 880 nm and compared with commercially available LiNbO3, demonstrating a sensitivity improvement of about an order of magnitude. The ability of volume holographic storage to wavelength-multiplex images was also investigated. Experimentally measured wavelength selectivity in a 1 mm thick LiNbO3 sample was 0.15 nm FWHM. We also investigated the BER of such memory systems by creating a noise model for holographic storage. Since the BER depends on the cross talk, it also depends on the wavelength separation of the stored images and strongly affects the number of images that can be stored. Experimentally measured BER will be compared with that of standard memory devices.
New approaches to compact diode-pumped mode locked lasers
Authors: Godil A. A. , Bloom D. M.
Published: February 2023

We introduce and develop a novel mode locker based on microwave dielectric resonators made of LiNbO3. We call this device a dielectric resonator/optical modulator (DROM). A 20-GHz DROM was used as an FM mode locker at the 84th harmonic of a conventional 238-MHz diode-pumped Nd:BEL (La2Be2O5) laser cavity. Depending on the mode locker drive frequency, two distinct regimes of mode locking were observed: 2.9-ps pulses at a repetition rate of 238 MHz and 3.9-ps pulses at a repetition rate of 20 GHz. With 800 mW of diode pump power, 50 mW of average output power was obtained. Next, a 2.85 GHz resonant microwave optical modulator was developed by using a LiNbO3 crystal in a cutoff metal waveguide. Round-trip phase modulation of 1 rad was measured with 0.5 W of microwave power. By using the modulator at the 12th harmonic of a 237.5 MHz diode-pumped Nd:YLF laser, again two regimes of mode locking were observed: 4.0-ps pulses at a repetition rate of 237.5 MHz and 4.5-ps pulses at a repetition rate of 2.85 GHz were obtained. The average laser power was about 400 mW for a diode pump power of 1.8 W.
System implications of optical fiber nonlinearities
Authors: Tkach R. W.
Published: February 2023

Optical amplifiers can compensate for the loss in lightwave transmission systems, and dispersion penalties can be avoided in dispersion-shifted fibers. The overthrow of these two limitations on system length and capacity brings the subject of fiber nonlinearity to the forefront. This tutorial will cover the basic nonlinear processes that occur in optical fibers and will describe how they may affect system performance.
Two-photon detection of light
Authors: Qu Y. , Singh Surendra
Published: February 2023

Fluctuation properties of light fields as reflected in two-photon detection experiments are discussed.
X-ray microscopy with a scanning laserplasmasource
Authors: Fedosejevs R. , Bobkowski R. , Pfauntsch S. J. , Michette A. G.
Published: February 2023

A scanning x-ray microscope system based on a fixed zone plate x-ray optic and a moving laser-plasma x-ray source will be described.
Coherence length enhancement of a nitrogen laser
Authors: Lee Hee S. , Lee Boon K. , Stewart B. W. , Fenichel Henry
Published: February 2023

The nitrogen laser is a source of W radiation which is easy to construct and inexpensive.
Modeling of the effect of dynamic gas lensing on beam-quality control of nuclear pumped lasers
Authors: Petra Maria , Eiji Suzuki , Miley George H.
Published: February 2023

The control of the extracted beam quality of a nuclear pumped-laser is a major issue.
Development of low cost large laser mirrors for a multimegajoule system
Authors: Billon D. , Belleville P. , Floch H. , Roussel A. , Novaro M.
Published: February 2023

CEL-V is investigating techniques for production of low cost components for a multimegajoule laser concept.
Fourier plane processing for optical joint transform correlators
Authors: Grycewicz Thomas J. , Horner Joseph L. , Javidi Bahram
Published: February 2023

In the output plane of the optical joint transform correlator, the correlation peaks are often difficult to detect and to accurately distinguish from noise spikes.
Self-pumped, photorefractive, phase-conjugate frequecy classifier
Authors: Khoury Jehad , Kane Jonathan S. , Woods Charles L.
Published: February 2023

In many applications such as optical computing it is desirable to have a method of multiplexing and demultiplexing information.
Femtosecond time-resolved coherence experiments
Authors: Kim Dai-Sik
Published: February 2023

Summary not available.
Observation of quantum dynamics via atomic beam deflection
Authors: Herkommer A. M. , Akulin V. M. , Schleich W. P.
Published: February 2023

The observation of the dynamics of a relaxating microscopic system on a macroscopic level would allow to gain deeper insight into the fascinating features of quantum mechanics.
Wave Guiding by Optical Vortex Solitons
Authors: Law C. T. , Swartzlander G. A.
Published: February 2023

We have reported recently the observations of optical vortex solitons (OVS) in a self-defocusing medium1 where the field has a stable and stationary dark core within a bright background field.
Spatial pattern dynamics in lasers
Authors: D’Angelo E.J. , Green C.
Published: February 2023

It has been proposed that topological defects are the cause of symmetry breaking in the transverse intensity distribution of lasers.
Lasers for advanced optical data storage.
Authors: Lenth Wilfried
Published: February 2023

Optical data storage exhibits a unique combination of capacity, performance and cost characteristics which compare favorably to those of magnetic hard-disk and tape devices in a number of important applications.
High-power operation of InGaAlP laser diodes
Authors: Itaya K. , Hatakoshi G.
Published: February 2023

Device design for reduction of an optical density in the active layer, essential for preventing catastrophic optical damage of the laser facet, enhances electron overflow and causes a deterioration in the temperature characteristics.
Photon-statistics control by field-atom interactions in photonic band structures
Authors: Kurizki Gershon , Sherman Boris , Akulin Vladimir M.
Published: February 2023

The density and spatial modulation of field modes should become better controllable in structures that exhibit photonic band gaps (PBGs)1.
On the behavior of an arbitrary atomic system in a strong quantum field
Authors: Chumakov S.M. , Klimov A. , Sanchez-Mondragon J.J.
Published: February 2023

We consider an arbitrary atomic system interacting with the quantum e.m. field in a lossless cavity.
Two-photon Raman laser
Authors: Gauthier David J. , Concannon Hope , Sukow David W.
Published: February 2023

Until recently, experimental research on two-photon lasers was hindered by the lack of suitable two-photon gain media.
Threshold versus radiance (TVR) functions for S-cone contrast sensitivity
Authors: Swanson William H.
Published: February 2023

Standard two-color increment threshold versus radiance (TVR) functions for short-wavelength-sensitive (S-) cones control S-cone adaptation state with a long-wavelength background and test S-cone sensitivity with a short-wavelength test.
Effect of modulation of single cone types on the hues of scotopic color contrast,
Authors: Buck Steven L. , Brandt Jeffrey L. , Ayers Michael S.
Published: February 2023

In scotopic color contrast, a photopic field induces a hue into a simultaneously presented, purely scotopic test field.
Infrared fiber-optic diagnostics for solid-propellant combustion
Authors: Wormhoudt J. , Kebabian P.L. , Kolb C.E.
Published: February 2023

Embedded infrared fiber optics have been used to carry out a direct absorption measurement across a small cavity inside a burning strand of nitramine solid propellant.
Folds and cusps of the visual motion field
Authors: Wildes Richard P.
Published: February 2023

In this talk an analysis will be presented that relates stable structures in visual motion fields to properties of corresponding 3D environments.
Coherence measurement of bright x-ray beams by intensity interferometry
Authors: McNulty Ian
Published: February 2023

Intensity interferometry1,2 is potentially suited to measuring the coherence of an x-ray beam produced by a high brightness source and, thereby, to measuring the size of the source itself.
Impedance-matching techniques in gain-switched laser diodes
Authors: Shu C. , Ho K. W.
Published: February 2023

A convenient method to generate short optical pulses from laser diodes is by electronic gain switching. As the series resistance of the diodes is usually a few ohms, the optimization of power transfer from the external circuits to the optical devices becomes a critical issue. By investigating the spectral content of the broadband input source and the measured diode impedance, we have designed a quarter-wave transformer for efficient coupling of the signal. The results are compared to those of a conventional broadband matching technique using a chip resistor. For all bias level below threshold, the former technique yields approximately a two-fold improvement in the output optical power. The results are attributed to higher ac power coupling due to the elimination of electrical loss in the resistor. The increase in optical pulse width as a result of narrow band matching in the transformer circuit is also studied. Minimal width of 51 ps is observed, as compared to 39 ps in the case of a chip resistor. The compensation in bandwidth is relatively small. We will also present computer simulated results on the power and bandwidth of the driving electrical signals. A good qualitative match with our experimental observations is obtained.
Linear polarization sensitivity
Authors: McClain Stephen C. , Chipman Russell A.
Published: February 2023

Remote sensing instruments often contain optical components, such as fold mirrors, diffraction gratings, and detectors, whose efficiency depends on the incident polarization state.
Conceptual design of an optical subsystem for an ultralightweight 1-m lunar-based tele­scope
Authors: Ruthven Gregory P. , Stier Mark T.
Published: February 2023

We present the results of a conceptual design of an optical subsystem for a lunar-based transit telescope for ultraviolet astronomy known as the Lunar Ultraviolet Telescope Experiment (LUTE.)
Beam-smoothing experiments at the third harmonic of the Nova laser
Authors: Pennington D. M. , Henesian M. A. , Dixit S. N. , Thompson C. E. , Powell H. T.
Published: February 2023

Nonuniformities in the focal spot power distribution in high power laser systems can significantly degrade the coupling of energy into inertial confinement fusion tar­gets, driving various instabilities.
Partially coherent periodic stop filtering for defect inspection
Authors: van der Gracht Joseph
Published: February 2023

A partially coherent periodic stop filtering system is proposed for defect inspection of periodic objects.
S-cone system does not contribute to perfect simultaneous color constancy
Authors: Kuriki Ichiro , Uchikawa Keiji
Published: February 2023

We carried out a color matching experiment to evaluate the degree of color constancy when illuminating and surrounding conditions were varied.
A cone-based linear model of spectral reflectances
Authors: Brown Richard O’Reilly
Published: February 2023

Several researchers have used principal components analysis to derive basis functions for spectral reflectances.
Excitation of a 3-D localized atomic electron wave packet
Authors: Noel Michael W. , Gaeta Z. D. , Stroud C. R.
Published: February 2023

Since the beginning of Quantum Mechanics physicists have been trying to find a quantum state in which an atom looks and acts classically.
Efficiency of coherent wavepacket oscillations induced by femtosecond pulse sequences in the weak field limit
Authors: Weiner A.M.
Published: February 2023

Several experiments, in which weak-field, femtosecond pulse sequences are used to control aspects of coherent wavepacket motion, have been recently reported.
Optoelectronic relational-database interface to parallel-access optical memories
Authors: Marsden Gary C. , Esener Sadik C.
Published: February 2023

Database management is one of the most common applications of computers and their associated storage.
Spatiotemporal dynamics of Kerr media pumped by Gaussian beams
Authors: Papoff F. , D’Alessandro G. , Oppo G.-L. , Firth W. J.
Published: February 2023

We analyze pattern formation in the transverse profile of a laser beam propagating through a thin slice of Kerr medium and reflected back by a mirror after propagation in free space1.
Time-resolved studies of wavelength-dependent laser-produced microplasmas
Authors: Simeonsson Josef B. , Miziolek Andrzej W.
Published: February 2023

UV laser produced microplasmas have been recently evaluated as potential novel detectors for gas chromatography.1 Microplasmas provide signals for photoacoustic, optogalvanic, as well as photometric detection. The emission from these microplasmas was subsequently wavelength-resolved and it has been shown that each analyte molecule exhibits a unique plasma emission spectrum.2 More recently, time-resolved microplasma emission studies were undertaken to determine plasma parameters such as electron density as well as neutral and ionic temperatures.3 Currently our research is aimed at exploring possible laser wavelength effects on the microplasma formation process and on microplasma characteristics.
Sensitive detection of nitrocompounds by using 193- and 226-nm radiation
Authors: Sausa R. C. , Lemire G. W. , Simeonsson J. B.
Published: February 2023

The development of laser-based sensors for the in situ detection of trace atmospheric compounds is of considerable interest.
Laser-induced-breakdown spectra in a coal-fired MHD environment
Authors: Zhang H. , Singh Jagdish P. , Yueh Fang-Yu. , Cook Robert L.
Published: February 2023

Laser-induced breakdown spectroscopy (LIBS) is a laser-based, non-intrusive, high-sensitivity optical diagnostic technique used to detect atomic and certain molecular species and measure the species concentration.
Compact frequency references for optical communications
Authors: Sudo Shoichi , Sakai Yoshihisa
Published: February 2023

The early explorers of laser technology expected that “the amount of information that can be carried by a communication channel is proportional to its frequency, and in principle the visible region of the spectrum between the wavelengths of 4,000 and 7,000 angstrom units could accommodate 80 million television channels.
Anomalous dispersion of dielectric constants in organic crystals
Authors: Yakymnsyshyn C. P. , jin Y. , Zhang X.-C.
Published: February 2023

Recently we reported the observation of efficient optical rectification and generation of sub-millimeter waves using the organic crystalline salt DAST (Dimethyl Amino N-methyl Stilbazolium Tosylate).1,2
Phase diversity measurements from pupil masking experiment
Authors: Restaino S. R. , Radick R. R. , Loos G. C. , Conley R. W.
Published: February 2023

As first proof of concept of a Fizeau type of beam combination experiment, we have performed a pupil masking experiment using the Vacuum Tower Telescope (VTT) of the National Solar Observatory at Sacramento Peak, New Mexico.
Phase-diversity restoration of solar images
Authors: Lofdahl Mats G. , Scharmer Göran B.
Published: February 2023

We have implemented a least-squares linearization technique for recovering phase information from simultaneously recorded focused and defocused solar images.
Correction of turbulence-induced space-variant aberrations by using phase diversity
Authors: Thelen Brian J. , Paxman Richard G. , Fienup James R.
Published: February 2023

Often the resolution of an incoherent imaging system is limited by phase aberrations which can arise from a wide variety of sources, including atmospheric turbulence.
Generation of tunable femtosecond VUV pulses by resonant four-wave difference-frequency mixing in xenon and amplification of such pulses in discharge-pumped F2 and optically-pumped Xe2 gain media
Authors: Glownia J. H. , Gnass D. R. , Sorokin P. P.
Published: February 2023

A practical method for generating femtosecond-time-scale VUV pulses at the few-tens-of-microjoules energy level in the spectral range 150-200 nm is discussed.
Application of optical levitation and trapping of dielectric spheres to the dynamometry of model biomembranes
Authors: Angelova M.I. , Martinot-Lagarde G. , Pouligny B. , Grehan G. , Gouesbet G.
Published: February 2023

We developed an experimental set-up for levitation, trapping and manipulation of dielectric particles which is an upgraded version of Buican’s1 original design.
Spatiotemporal properties of photorefractive beam fanning
Authors: Vachss Frederick , Ewbank Mark
Published: February 2023

The fanning of beams resulting from amplified scattering poses a significant limit on the signal-to-noise ratio achievable in high gain photorefractive amplifiers.
Temperature effects on optical gain and storage in barium titanate
Authors: Leu G.-J. , Li G. , Luo Y. , Stever T. , Fiddy M. A.
Published: February 2023

There has been much research carried out into the photorefractive properties of barium titanate.
Filled-lattice tungsten-bronze materials for photorefractive applications
Authors: Neurgaonkar R. R. , Cory W. K. , Oliver J. R. , Sharp E. J. , Wood G. L. , Salamo G. J.
Published: February 2023

Recently we have established that the filled lattice structure (15- and 12-fold sites filled) tungsten bronze (Ba,Sr)6Ti2Nb8O15(BSTN) and Ba2–xSrxK1–y.NavNb5O15(BSKNN) crystals exhibit much faster response than the prototype SBN:60 (partially filled lattice) with substantial optical gain.
Optical fiber-tip and fiber-damage control device for medium-power Nd:YAG laser delivery systems
Authors: Falciai R. , Pascucci T. , Schena A. , Cosi F.
Published: February 2023

In the present work, a very compact optical fiber-tip and a fiberdamage control device, both designed to operate in a fiber-optic delivery system, are presented.
Error propagation in laser-beam spatial parameters
Authors: Jones Richard D. , Scott Thomas R.
Published: February 2023

We have performed a propagation-of-errors analysis on two methods used to determine the spatial parameters of a laser beam.
Relationship between power efficiency, bandwidth, and parallelism of optical fan-in networks
Authors: Euliss G. W. , Athale R. A.
Published: February 2023

The use of optics for computing is attractive because it offers the promise of fundamentally high bandwidth and parallelism.
2-D WDM optical interconnections for simultaneous and reconfigurable communication among many planes
Authors: Willner A.E.
Published: February 2023

The ability to efficiently connect many high-speed ports or 2-dimensional (2-D) sensor arrays is important for large-capacity data processing.
Phase measurements of partially coherent light beams by photon counting
Authors: Fougères A. , Noh J.W. , Mandel L.
Published: February 2023

The technique developed previously for studying phase differences between quantum fields by photon counting1 has been applied to two partially coherent light beams with controllable degree of coherence.
Photon-number amplification and readout below the standard quantum limit
Authors: Goobar E. , Karlsson A. , Björk G.
Published: February 2023

We have performed quantum non-demolitional type experiments with a simple and inexpensive photodetector-light emitting diode setup.