bluuebunny/crossref_metadata_2025 huggingface dataset:
Ignition and maintenance of laser-supported detonation waves
Authors: Rollins C. , Weyl Guy M.
Published: February 2023

Ground-based lasers can be used to propel rockets into space. The double-pulse laser-supported detonation1 (LSD) wave concept for a thruster involves the use of a first laser pulse to vaporize the propellant followed by a delayed second pulse that ignites a plasma. Large specific impulses can then be achieved by expansion of the gas. The means of igniting plasmas at low fluences have been analyzed. An aluminum flake embedded in the (solid) propellant of 0.2-μm thickness will vaporize at fluences as low as 2 J/cm2, and the metallic vapor will break down at relatively low irradiances (/ ≳ 5 × 107 W/cm2 for λ = 10.6 μm). Maintenance of an LSD wave requires complete absorption of the laser beam in an absorption front traveling supersonically with respect to the upstream gas.1 Gas heating obtains by electron-neutral and electron-ion inverse bremsstrahlung absorption of laser radiation. Calculations of propellant heating and ignition from conditions behind the shock to Chapman jouguet conditions have been carried out for H2O. The presence of a small amount of easily ionizable seed can lower the maintenance thresholds. We find // ρ ≳ 5 × 108W cm/g for 1% lithium seed in H2O over a density range of 10–4 < ρ < 10–2 g/cm3.
Comparison of effective medium models
Authors: Hickey Carolyn F.
Published: February 2023

Impurities and subwavelength microstructure can significantly change the optical properties of thin films. Effective medium theories provide a simple and useful description for such inhomogeneous media. However, there has been controversy over which theories are best applicable. This paper compares the predictions of several models to the observed spectrophotometric data for thin films containing SmS crystals and amorphous impurities. When pressure is applied, a fraction of the SmS crystals becomes metallic.1,2 These films then go from being essentially two-component systems to three-component systems. They thus provide an interesting test for differing effective medium theories. The coated Bruggeman, simple Bruggeman, and Maxwell Garnett models are considered.
Bandpass AR coating design for bismuth silicon oxide
Authors: karim Zaheed , Garrett Mark H. , Tanguay Armand R.
Published: February 2023

Bismuth silicon oxide is a high-index (2.54 at 514 nm) electrooptic and photorefractive material used for optical information processing devices such as the Pockels readout optical modulator (PROM), the photorefractive incoherent-to-coherent optical converter (PICOC), and volume holographic optical elements (VHOEs). In the latter two applications, the bismuth silicon oxide crystals have typically been used uncoated, even though the resultant high single-surface reflectivity (~19%) gives rise to problematic multiple reflections. For example, in the use of two-beam coupling experiments in Bi12SiO20 for signal amplification1 or materials parameter analysis, the modulation depth of the volume holographic gratings is reduced by multiple reflections, and the effective gain is decreased.2 For such experiments, a two-layer quarterwave stack of electron-beam deposited zirconium dioxide and magnesium fluoride was employed to fabricate a broadband (500–800-nm) AR coating, which encompassed both the write (514-nm) and read (633-nm) beams. At both wavelengths, the reflectivity was reduced to ~1 %, and the coating was found to be relatively insensitive to large angles of incidence (of the order of 45°). In two-beam coupling experiments, the effective gain was increased by 10%, and the resolution of the technique was significantly improved for low-intensity measurements.
Photothermal detection of plasmon surface polariton-induced optical absorption on rough metal surfaces
Authors: Grygier R. K. , Coufal Hans
Published: February 2023

Plasmon surface polaritons (PSPs) exist as collective oscillations of the electron density at a metal surface. These longitudinal polarization waves are confined to the metal surface, since they decay exponentially in the direction normal to the surface. Optical coupling to the PSP occurs when there is a periodic or random surface structure which allows the parallel component of the incident wave vector to match the PSP wave vector. Enhanced optical absorption will occur depending on the incident optical frequency and polarization, surface roughness parameters and orientation, angle of incidence, and the metal’s dielectric properties. Photothermal techniques offer an ideal way to study such nonradiative processes since only the absorbed portion of the incident energy contributes to the photothermal signal. In particular, the pyroelectric thin-film calorimeter is well suited for this purpose due to its extreme sensitivity of a few nanojoules and a time resolution of better than 100 ns. Periodic and randomly rough metal surfaces were investigated using both cw and pulsed lasers. Results are presented for a variety of surface roughness conditions.
SHG investigation of liquid crystal-silane interfaces
Authors: Mullin C. S. , Guyot-Sionnest P. , Feller M. , Chen W. , Shen Y. R.
Published: February 2023

Using optical second harmonic generation, we have studied the interaction between 4′-n-octyl-4-cyanobiphenyl (8CB) liquid crystal molecular monolayers and glass substrates treated with three types of silane coupling agent: MAP, DMOAP, and OTS. On adsorption from the gaseous phase at atmospheric pressure, we measure the coverage, orientation, and binding energy of monolayers on these substrates and find that, although the bulk alignment differs from different silanes, the alignment of the monolayer is unaffected. We also find a polar layer of liquid crystal at the surface of MAP and DMOAP, unlike the dimerized layers that are found in the bulk liquid crystal. The number of binding sites on these silanes is approximately equal and less than the number of sites on clean glass. Their binding energies are also slightly below that on glass. On OTS, no polar layer formed, although a dimerized bilayer was present.
Weak localization of optical wave on a rough metal surface
Authors: Arya Karamjeet
Published: February 2023

Anderson localization of the electromagnetic surface plasmon polariton (SPP) on a randomly rough metal surface has been predicted theoretically. The physical basis of the localization is the same as in the case of an electron in a random potential; i.e., the diffusion coefficient vanishes because of the coherence interference between scattered waves from random scatterers. However, there are yet no experiments for the observation of these effects. We show that such effects can be observed in reflection and transmission experiments on the SPP on a rough metal surface. For example, in reflection experiments, a back-scattered peak with twice the intensity compared to diffused scattered intensity is expected. The use of an attenuated total reflection prism is suggested for converting an incident photon into a SPP and back into a photon for better coupling efficiency.
Propagation of quantization error in a computer-generated hologram design algorithm
Authors: Mait Joseph N.
Published: February 2023

One technique for designing Fourier holograms is an iterative algorithm wherein constraints are alternately placed on the reconstruction, or response, of the hologram and on the hologram itself. Although the ability of the algorithm to reduce quantization error is known,1 the relationship between the quantization scheme and quantization error as a function of iteration number has not been previously considered. A preliminary model for the propagation of quantization error within the iterative algorithm has been developed and is presented. The discussion is motivated using the dual-phase construction of a Fourier hologram.2 Dual-phase construction allows for the comparison of several different, but practical, quantization schemes, including minimum-distance quantization, closest-phase quantization, and polar quantization. Analyses indicate that the relative performance of the different quantization schemes changes as the number of iterations increases. Experimental verification of these results is presented.
Generation of large spot arrays from a single laser beam via multiple imaging with computer-generated phase gratings
Authors: McCormick F. B.
Published: February 2023

A light efficient technique for generating large (100 × 100+) arrays of uniform intensity spots of good contrast is proposed. One application of spot arrays such as these is as power supplies for optical logic devices in 2-D optical computing architectures.1 Previously described spot array generation techniques may exhibit significant spot nonuniformity when producing large spot arrays. This nonuniformity is due to quantization and fabrication errors in the transition locations, phase-depth errors, and computational errors.2 This spot generation technique utilizes phase gratings to produce small spot arrays (<20 × 20) whose extra orders are then spatially filtered. This small spot array image is then multiply imaged via another phase grating to produce the large spot array. Since each grating need only produce a small number of spots, the design computation and fabrication constraints are simplified. An experimental demonstration of this technique for a 77 × 77 array is presented as well as a discussion of potential limitations.
Atmosphere as an optical system component
Authors: Hall Freeman F.
Published: February 2023

The atmosphere contributes the characteristics of an electronic filter, noise generator, and gain limiter to the performance of electrooptical systems that must operate in the real world. This tutorial tells how to calculate the atmospheric spectral transmittance from the UV to the IR using system-appropriate models. The effects of gaseous and vapor absorption of aerosol and cloud particle scattering and absorption and of refractive-index turbulence are described. Understanding the optical physics involved is emphasized.
Long-baseline infrared spatial interferometer
Authors: Bester Manfred , Danchi W. C. , Townes Charles H.
Published: February 2023

The infrared spatial interferometer (ISI) is a high-resolution aperture synthesis imaging system for the 10-μm region located at Mt. Wilson Observatory since Jan. 1988. The compactness of the novel-design Pfund telescopes allows all optics and electronics to be mounted in two semitrailers.1,2 Each of the two telescopes consists of a fixed f/3.14 parabolic mirror with 1.65-m aperture and a 2-m diam flat mirror in an altaz fork mount, which tracks the source. Hererodyne detection is achieved using LN2 cooled HgCdTe photodiodes and phase-locked CO2 laser local oscillators. The quantum efficiency including telescope transmission losses is ~25%, and the IF passband is 200–2000 MHz. Phase fluctuations on the LO signal caused by the atmosphere between the telescopes are compensated with a path length control system. As in many radio interferometers the fringes are stopped with a lobe rotator acting on the LO system. Correlation of the received signals over the IF passband is maintained with an IF delay line. A newly costructed He–Ne laser metrology system ensures that the telescopes can be pointed to a precision of ~0.01 sec of arc. Critical internal distances can also be monitored with this system. In addition the telescopes are equipped with conventional optical encoders. Although designed for baselines up to 1000 m, the initial range is 4–35 m yielding angular resolutions of 0.25–0.03 sec of arc.
Chromatic induction: a misdirected attempt at color constancy?
Authors: Walraven J. , Benzschawel T. , Rogowitz B. E.
Published: February 2023

Both color constancy and chromatic induction were studied in a computer-driven color display that simulated an array of Munsell samples (25% reflectance) that was illuminated by either standard white light (D65) or various colored illuminants. The samples were separated by an achromatic grid (100% reflectance) that could be selectively illuminated. Three conditions were studied: (a) constancy, with samples and grid illuminated by the same source; (b) induction, with colored light confined to the grid and white light to the samples; (c) dark grid, with the source illuminating the samples only.
Nonlinear transmission of carbon black in suspension
Authors: Mansour Kamjou , Van Stryland Eric W. , Soileau M. J.
Published: February 2023

We have observed fluence-dependent nonlinear transmission in a suspension of carbon particles in a water/ethylene glycol solution. The particle sizes are ~300- with ~5000-Å agglomerates. We see the onset of nonlinearity at input energies as low as 0.2 μJ using tightly focused 10-ns (FWHM) 532-nm pulses. Assuming strong absorption by the carbon a straightforward estimation of the temperature rise by linear absorption gives temperatures of a few thousand degrees celsius. Therefore, we associate this nonlinear transmission with localized rapid heating of the particles, which leads to thermionic emission and the creation of an expanding plasma, which both absorbs and scatters subsequent radiation. Evidence for this interpretation is given in experiments where we simultaneously monitor nonlinear transmission, nonlinear scattering, and nonlinear absorption (using the photoacoustic technique). The most striking nonlinearity is seen in side-scattered light which increases drastically with increased input energy. This is consistent with the growth in size and, therefore, increased scattering of rapidly expanding microplasmas. In addition, we find that the nonlinearity disappears rapidly with repeated laser firings indicating material changes. Flowing the suspension returns the nonlinearity as expected.
Accurate method to determine the eigenstates of polarization in gyrotropic media
Authors: Maldonado Theresa A. , Gaylord Thomas K.
Published: February 2023

Many practical modulator materials include combinations of electrooptically induced birefringence, optical activity, and/or Faraday rotation. Thus there exists a need for a procedure to design and analyze devices fabricated with materials exhibiting any or all of these effects. A simple method employing an extension of the general Jacobi method is introduced for determining properties of the two allowed eigenpolarizations for an arbitrary direction of propagation in a general lossless, electrooptic, and gyrotropic medium.
MoS2 photoexcited as exciton peaks at room temperature
Authors: Chang Gui-Fen J. J. , Ma Gen-Yuan , Zhang Guang-In
Published: February 2023

The maybe superconductive and optobistable 2H MoS2 compound was first studied by a photoacoustic spectroscopic method at room temperature. Our PAS measurements were performed on a conventional PAS set with particular protection against thermal and vibrational disturbances. The incident light from a 250-W sodium lamp through a monochromator fell on the MoS2 cleavage surface of an ~50-μm thick sample, which was stuck to a piezoelectric ceramic sensor, in the measuring wavelength range from 540 to 740 nm at room temperature. We obtained three strong peaks at the absorption edge, namely, 595 nm (2.084 eV), 648 nm (1.913 eV), and 680 nm (1.823 eV), which agree well with respect to their positions and shapes with that obtained by Frindt and Yoffe1 at 77 K by an ordinary method. We verified these results further on electrolyte electromodulation spectra and photomodulation reflectance measurements. These two peaks at 595 and 648 nm can be identified by calculating the absorption spectrum by the well-known transmission formula T = (1 – R)exp(–al) or by, more formally, Fermi’s golden rule through Loudon’s scattering matrix elements from the band structure of 2H-MoS2 schemed in the paper of Evans and Young.2 The peak appearing at 680 nm is probably due to the impurity activities.
Experimental investigation of the effects of atmospheric scintillation on image synthesis with intensity interferometer data
Authors: Idell Paul S. , Gonglewski John D. , Voelz David G. , Levine B. Martin , Spielbusch Brian
Published: February 2023

Since the average brightness distribution of astronomical objects and the mutual intensity (complex coherence function) of the observed field are related by a Fourier transform, it is possible to synthesize images from far-field correlation measurements. Owing to the fact that detected intensities (rather than complex fields) are correlated at the receiver, intensity interferometry is an approach to measuring such correlations, which is largely insensitive to the effects of the earth’s atmosphere. We investigate the effect that atmosphere-induced fluctuations in the detected field amplitude (i.e., atmospheric scintillation) have on one’s ability to recover imagery using intensity interferometer data. To model the effects of the atmosphere on two-point intensity correlation measurements, we have adopted the theory of Beran and Whitman1 which provides expressions for the scintillation covariance function (in the case of isoplanaticity) and a first-order isoplanatic correction. We report on our attempt to verify these relations in a laboratory setting using Gaussian phase screens of known statistics2 and an image recovery methodology known as imaging correlography.3 We also investigate the performance of postdetection processing schemes applied to compensate for the effects of scintillation in the digitally recovered imagery.
Measurements of atmospheric optical turbulence with a large telescope
Authors: Winker David M.
Published: February 2023

An experiment to investigate the basic characteristics of atmospheric turbulence has been conducted on the 107-in. telescope at McDonald Observatory in west Texas. A Hartmann wavefront sensor having about 1000 subapertures in the unobscured portion of the aperture has been used to measure the phase and intensity of starlight over the aperture of the telescope. An image of the star is recorded simultaneously with the pupil plane information. A gated image intensifier allows 1-ms exposures, sufficient to freeze the atmosphere. Simultaneous measurements of r0, using a separate instrument, and measurements of temperature differences along the optical path within the telescope have also been made. The experimental design is discussed along with an overview of the results of the data analysis.
Wave optics in terms of vector and scalar potentials
Authors: Gamo Hideya
Published: February 2023

According to Feynman, E and B are slowly disappearing from the modern expression of physical laws and are being replaced by A and Φ.1 This can be understood by considering that the Hamiltonian or Lagrangian of an electron emitting or absorbing the photon contains A and Φ instead of B and E, respectively. The physical meaning of vector potential A has been clarified by the recent interference experiment of electron waves.2 Hence I shall describe the wave optics of magnetic vector potential A and scalar potential Φ in conjunction with the plane waves and electric and magnetic dipole oscillators. The boundary conditions for A and Φ are derived for both dielectric and conducting boundaries and are shown to be consistent with those for the electromagnetic waves. The field energy density, Poynting, and reciprocity theorems for A and Φ waves are also treated.
New method for specifying nonradiating sources and their fields
Authors: Gamliel Avshalom , Kim K. , Wolf E.
Published: February 2023

The subject of nonradiating source distributions is important in connection with the uniqueness of various wave theoretic inverse problems.1 In spite of this fact, no general technique appears to have been developed so far for specifying all non-radiating sources that can be associated with a given source domain. Moreover, relatively little is known about fields that nonradiating sources generate within the region that they occupy.
Light scattering in generalized eikonal approximation
Authors: Chen Tuan W.
Published: February 2023

The generalized eikonal approximation (GEA) method developed earlier for particle scattering by a potential1 is applied to light scattering by a dielectric medium. In this method, the propagation of light inside the medium is assumed, just as a usual eikonal approximation method, rectilinear but with a parametrized propagator. This way, the simple closed form of eikonal scattering amplitude is preserved but with two parameters to be adjusted for minimizing the errors. The parameters are determined from geometrical optics consideration and high-energy behaviors of Qext. As a specific application, the light scattering by a uniform dielectric sphere is calculated and numerically compared with the results from the Mie method. The extensive comparison shows that GEA works excellently. It gives rise to dramatic improvements over the usual eikonal method at high energy and for the index of refraction n close to one. More amazingly, it also works even at low energy and for n as large as 5. The GEA formalism gives a clear-cut picture of how light propagates through a medium. Its applications to many scatterer systems is immediate and most interesting.
Probability density function for two-scale non-Gaussian scattering
Authors: Phillips Ronald L. , Andrews Larry C.
Published: February 2023

The non-Gaussian nature of optical wave scattering by a number of different mechanisms has been modeled as a compound random modulation process. The success of this modeling approach has been due to the scattering mechanisms themselves having two discernible scales of fluctuations. A small-scale fluctuation appears to have a modulation over a much larger scale. This modulated scatterer gives rise to a similar scattered optical wave. The scattered optical wave appears to have a fine structure whose strength is modulated by a more coarse structure. The probability density function (PDF) of the detected intensity can be calculated from conditional statistics. The small-scale rapid fluctuations are treated as a conditional PDF and then averaged over the PDF of the large-scale slower fluctuations. This approach has been used to describe scattering by surfaces, phase screens, and extended path turbulence. A more exact approach to this two-scale phenomenon is to express the scattered field as a sum of scattered components, i.e.,
Optical rectification effect of small metal and degenerate n-type semiconductor composites
Authors: Shen T. P. , Rogovin D.
Published: February 2023

We studied the optical rectification effect of a small-particle composite, which consists of small metal or degenerate n-type semiconductor spheres embedded in a dielectric host, in the presence of an intense radiation at the surface plasma frequency ω
s
of the spheres. We adopt the quasi-hydrodynamic theory to describe the dynamics of the electrons and include the screening effect resulting from the gradient of the quantum pressure of the electrons. The total electric field of the small spheres obeys Poisson’s equation. We solve the hydrodynamic and electrostatic equations perturbatively. The first-order solutions are resonantly enhanced at ωs. The second-order equations have inhomogeneous drive terms, which are doubly resonantly enhanced at ω
s
. The second-order solutions consist of second harmonic1 and dc rectified parts. Here we examine the rectification effect and consider a possible scheme to measure it. In particular, the Cherenkov radiation of an effective moving polarization induced by the optical rectification effect inside the small sphere composite can be generated by focusing a short pulse onto the composite and may be observable.
Optical nonlinearities arising from enhanced carrier transport
Authors: Garmire Elsa
Published: February 2023

In n–i–p–i and multiple quantum well hetero-n–i–p–i structures, semiconductor depletion regions, and hetero-Schottky barriers, as well as in photo­refractive materials, transport of optically induced carriers within internal or externally applied fields alters these fields. Field-dependent effects on optical transmission such as the linear electrooptic effect, electroabsorption, and electrorefraction cause effective optical nonlinearities which may be very large and materials very sensitive. As an example, in the hetero-n–i–p–i structure, refractive-index changes as large as –0.01 occur at intensity levels of only 0.7 mW/cm2.
Low-Intensity optical bistability in a quasi-periodic nonlinear multilayered structure
Authors: Leung K. M. , Lin Lida
Published: February 2023

We consider the scattering of a transverse-electric electromagnetic plane wave with a multilay­ered structure which is composed of linear layers of two different types constructed according to the Fibonacci sequence and a nonlinear dielectric film. In the absence of the nonlinear film and for a finite total thickness of the linear layers, the transmission coefficient goes to zero for certain ranges of the optical path length. The transmission coefficient can drop precipitously from a value comparable to unity to practically zero when the optical path length changes by a part in ten thousand. In the presence of the nonlinear film, which in a sense changes the effective optical path length with changing incident intensity, we find a highly intensity sensitive optical bistable behavior in the transmission coefficient of this multilayered structure.
Ferroelectric liquid crystal tunable filters
Authors: Masterson Hugh J. , Johnson Kristina M.
Published: February 2023

Ferroelectric liquid crystals (FLCs) have advantages for information processing due to their sub­microsecond switching speed, high birefringence and contrast ratio, low-power dissipation, and low cost. We describe a tunable wavelength filter using FLCs. These filters are capable of narrow-bandwidth operation with tunability in the visible and IR spectrums (300 nm to 3 μm). Initial results show high-speed switching between two channels centered at 475 and 625 nm with 50-nm bandwidth. A six-channel filter has been designed with a 10-nm bandwidth and good sidelobe suppression. Experimental data fit extremely well with theoretical prediction as verified by computer simulation. The filter is insensitive to variations of 10% in the FLC device thickness. Applications for the filter include increasing communication channel capacity in broadband user services via wavelength division multiplexing.
Photoaddressed ferroelectric liquid crystal devices
Authors: Armitage David , Thackara John I. , Eades Wen-Dell D.
Published: February 2023

Ferroelectric liquid crystal (FLC) devices have a speed and storage advantage over nematic liquid crystal (NLC) devices.1 We are developing a family of photoaddressed liquid crystal spatial light modulators (SLMs), including FLC devices, for optical processing applications. We find that photoaddressing structures that are effective in addressing NLC cells often prove ineffective for FLC cells, which is revealed in transient imaging effects and image fading and blooming. This is probably associated with a lack of ac symmetry in the photoaddressing element, which leads to a dc component in the addressing voltage. The FLC device is more sensitive to spurious dc potentials due to its permanent dipole moment and lower ionic mobility. Possible improvements in the photoaddressing structure are discussed. The electroclinic effect associated with the FLC phase can provide submicrosecond modulation at reduced sensitivity over a limited temperature range.2 The value of this effect in SLM applications is examined, where the higher voltage requirement is shown to compromise the resolution.
Multiplexed ferroelectric liquid crystal spatial light modulators
Authors: Pagano-Stauffer L. A. , Matuszczyk T. , Handschy M. A. , Clark N. A.
Published: February 2023

Ferroelectric liquid crystals (FLCs) exhibit fast low-voltage low-power electrooptic switching making them good candidates for spatial light modulators (SLMs). Since they are also bistable and have a sharp dynamic switching threshold, their electrical addressing can easily be multiplexed, promising SLMs with a large number of elements yet with an economical number of electronic drivers. We present studies of FLC SLMs employing matrix multiplexing where the addressing of N2 elements requires N row and N column electrodes. Waveforms applied to chosen row and column electrodes switch the pixel at their intersection. Minimizing the effect of the switching waveforms on the unselected pixels in the same row and column requires careful optimization of the waveform, the FLC material, and the surface treatment. Our experimental data include measurements of optical response, specifically contrast ratio, for a variety of different FLC materials and waveforms.
Computer-aided design for computer-generated holograms
Authors: Lee Sing H.
Published: February 2023

Applications of computer-generated holograms (CGHs) have expanded beyond the well-known area of optical testing to include diffractive optics, optical filters for pattern recognition, and 3-D display. The CGHs fabricated by commercially available optical or electron-beam writers are of special interest because they have a large space- bandwidth product (number of pixels in the hologram, ≥ 1010) and have high resolution (≤1 μm). The processes of designing and fabricating CGHs are often laborious. Depending on the background of the system designer, who contemplates the use of CGHs, he may be bewildered by the array of encoding schemes, the potentially explosive computational and data storage requirements, or the poorly defined procedures for transferring the design into a physical element. This situation is not unlike the conditions in mechanical and electronic design that prompted the creation of computer-aided design (CAD) work stations.
Electron-beam written computer-generated diffractive optical elements
Authors: Smith Robin W. , West A. A.
Published: February 2023

This work is concerned with the production of novel diffractive optical elements. These are computer generated and written by electron-beam lithography as binary amplitude, chrome on glass, masters. These elements can be used in either transmission or reflection.
Phase-only computer-generated holograms produced by an ion exchange method
Authors: Yatagai Toyohiko , Sugawara Ryoichi , Hasegawa Hideki , Seki Masafumi
Published: February 2023

To increase the diffraction efficiency of a binary computer-generated hologram (CGH), a phase- only binary hologram of which index distribution is modified by using an ion exchange method is proposed. The glass substrate is immersed at an elevated temperature around the glass transition temperature in a molten salt containing ions that increase the refractive index of the glass. The ions are diffused only through the window area of the mask in the glass substrate. Theoretically we expect the increase of the diffraction efficiency as a factor of 4 in an optimum case. To verify the theory, we produced the Lee-type phase-only Fourier transform CGH with 64 × 64 sample points. The phase difference is ~0.8π. Due to interferometric observation of a sliced sample cross section, the diffusion depth of ion migration is estimated as ~15 μm. Scattering noise is very low in the first orders and the zero order in the reconstructed plane. The diffraction efficiency of the phase-only CGH is 3.8 times as large as the conventional one.
Mie scattering calculation of B-R and F-R algorithms
Authors: Chao Y. F.
Published: February 2023

The A
n
of Mie scattering coefficients can be calculated by backward recurrence through a continued fraction technique,1 but extra terms are needed to obtain a stabilized A
n
value; thus forward recurrence is still preferred if the terms are needed before it becomes unstabilized. Using both forward and backward recurrence to study A
n
, we are able to determine the term where the forward recurrence is still allowed. By relating it to the refractive index of the medium, we find in the nonabsorbing medium, the valid term is proportional to the product of the refractive index of the medium and its size parameter. As the imaginery refractive index increases the valid term decreases, but it reaches the minimum as the imaginary part equals the real part of the refractive index. Using the nonabsorbing medium as a reference, we determine the valid term as the imaginary refractive index is not zero. The relationship of the valid term vs the precision of the machine is under study. This research was done on a twelve-digit HP 9845.
Analysis of infrared scattering from a dielectric-mounted frequency selective surface
Authors: Schimert Thomas R. , Chan C. H.
Published: February 2023

Periodic frequency selective surfaces (FSSs) have been used extensively as filters, output couplers, diplexers, and interferometers in the far-IR and millimeter wavebands for a number of years. Microlithographic advances now make it possible to fabricate these devices for use in the mid-IR (4-12 μm). The analysis of IR scattering from a dielectric-mounted FSS involves the solution of an electric field integral equation obtained using the standard Green's function techniques relating the induced current distribution on the FSS to the incident excitation field. The method we describe represents a generalization of the method for scattering from a freestanding FSS.1 The dielectric mounting generally includes dielectric layers and/ or substrate on either side of the FSS. The Green’s function in the presence of the dielectric layers is derived using the spectral domain technique. 2 Comparison to experimental results obtained for resonant metal dipole arrays is presented. Our analysis takes into consideration the lossy nature of metals in the IR. The treatment of stacked FSSs and/or multiple dielectric layers is also discussed. The method involves cascading the scattering matrices of the individual elements, which for an FSS includes the immediately adjacent dielectric layers.
Polarization Switching with Sodium Vapour in a Fabry-Perot
Authors: Hamilton M.W. , Sandle W.J.
Published: February 2023

We report results of an experiment which demonstrates switching of the polarization state of the output of a near-concentric Fabry-Perot containing sodium vapour, excited via the homogeneously broadened Dl transition. An example of the output, for linearly polarized laser input, at 1.5 GHz below line centre (illustrated in figure 1) shows switching with hysteresis at high input power (~400 mW) due to saturation, as well as the switching at lower power (~200 mW) due to optical pumping effects.
Vacuum-Deposited Thin-Film Interferometers as Bistable Devices Operating Continuously at Room Temperature
Authors: Apanasevich S.P. , Karpushko F.V. , Sinitsyn G.V.
Published: February 2023

Bistable operation of a nonlinear thin-film semiconductor interferometer, fabricated by vacuum deposition, was first observed in [1]. Refractive index nonlinearity required was achieved in a ZnS-spacer of submicron thickness with the input light beam intensity of about 6 kW/cm2.
Nonlinearities at the Bandgap in InAs
Authors: Poole Craig D. , Garmire E.
Published: February 2023

InSb has been shown to exhibit bistability and a very large nonlinear index.1 A semiconductor which is similiar, but which has a bandgap at shorter wavelengths is InAs. In this talk we present measurements of saturable absorption in InAs using an HF laser, which matches the bandgap of InAs at temperatures from 5° to 100° K. Using these measurements we have calculated a nonlinear refractive index of n2 = 2x10−5 cm2/W for light near but below the bandgap. These numbers are comparable to those measured in InSb and indicate that InAs may be a good material for bistable devices.
Mirrorless Intrinsic Optical Bistability Due to the Local Field Correction in the Maxwell-Bloch Formulation
Authors: Bowden C. M. , Hopf F. A. , Louisell (deceased) W. H.
Published: February 2023

The local field correction (LFC) is associated with the passage from microscopic to macroscopic electrodynamics. The conventional derivation of the LFC is found in Jackson1, and the implication is that the correction is due to all of the atoms in the system, which implies some kind of collective phenomenon. In the work reported here, we draw heavily upon the discussion of the LFC of Van Kranendank and Sipe2 (KS).
Distributed Feedback Bistability in Channel Waveguides
Authors: Stegeman G.I. , Liao C. , Winful H.G.
Published: February 2023

Two current goals in the area of optical bistability are (1) to reduce the power required for switching between two states, and (2) to reduce the material volume (and hence power dissipation). An obvious approach is to minimize the cross-sectional area of the beam, for example by using channel waveguides of the type shown in Fig. 1. A grating milled into the surfaces can be used as the distributed feedback mechanism. In this paper we analyze a channel, guided wave, distributed feedback geometry and present numerical results for InSb waveguides.
Polarization Bistability in Cholesteric Liquid Crystals
Authors: Winful Herbert G.
Published: February 2023

Cholesteric liquid crystals possess an intrinsic helical structure which enables them to selectively reflect circularly polarized light if the wavelength of the light matches the pitch of the helix. We recently showed that intense light can change the pitch of the cholesteric and lead to a bistable reflection characteristic for wavelengths in the Bragg regime1. We have now extended our analysis to the regime of wavelengths much shorter than the helix pitch. In this limit (known as the Mauguin limit) there are no Bragg reflections and, except for normal dielectric reflections, an incident wave will enjoy 100% transmission. Since the cholesteric represents a twisted, birefringent medium, the polarization state of the light will evolve periodically in space.
Simulations of the Dynamics of Optical Bistability with Fluctuations.
Authors: Koch S.W. , Schmidt H.E. , Haug H.
Published: February 2023

The Langevin-equation (1) for the fluctuating light-field E in a nonlinear semiconductor resonator has been derived in Ref.[1]: All quantities are dimensionless, εi being proportional to the amplitude of the incoming field, κ is a damping constant, ω" is the ratio of imaginary and real part of the dielectric function and Δ is proportional to the detuning. The additive term f(τ) is the classical noise source representing a Gauss-Markov process. The staionary properties of eq.(1) have been investigated in Ref.[1] and the details of optical bistable operation has been determined.
Instabilities and Chaos in TV-optical feedback
Authors: Häusler G. , Streibl N.
Published: February 2023

The simplest TV-optical feedback experiment is performed by a TV-camera looking onto its own monitor. If we introduce some signal processing into the system as convolutions, image subtraction, non1inearites, etc., there are many applications: in a first approximation we assumed linear systems and we obtained systems for image restoration, iterative image processing and for the solution of partial differential equations [1]. However, the world is nonlinear, and if we introduce nonlinearity in our feedback loops completely new effects may occur. These effects occuring in many different physical systems are called "synergetic" by H. Haken [2].
Polarization Switching with J = 1 2 to J = 1 2 Atoms in a Ring Cavity
Authors: Sandle W.J. , Hamilton M.W. , Ballagh R.J.
Published: February 2023

This paper reports a steady-state theory for the polarization behaviour1 of the output of a ring optical cavity that contains a vapour of atoms with a driven

J
=

1
2

to

J
=

1
2

transition. The input laser radiation may have arbitrary polarization and detuning. We have extended a previously reported theory2 (which includes analytic results for zero detuning of the incident laser and zero magnetic field) to include detunings and magnetic fields.
Optical Bistability Based on Self-Focusing
Authors: Smith P. W. , Eilenberger D. J.
Published: February 2023

Two years ago, the first proposal and demonstration of self-focusing optical bistability was published.1 In this paper it was shown that a self-focused beam in a nonlinear medium would exhibit hysteresis if the beam were reflected back on itself. The effect was demonstrated using a dye laser beam and Na vapor as the nonlinear medium. The optical hysteresis observed is in good qualitative agreement with a recently - published analysis of this system.2 By taking account of the saturation of the nonlinearity, more complex behavior has been predicted.2 This behavior is due to oscillations of the spot size as the self-focused beam propagates through the nonlinear medium. In this paper we report on our experimental studies of optical multistability due to these spot size oscillations.
Precise Measurements of Bistability in a CO2 Laser with Intracavity Saturable Absorber
Authors: Arimondo E. , Dinelli B.M. , Menehi E.
Published: February 2023

Optical bistability in a laser with an intracavity saturable absorber is a phenomenon theoretically investigated firstly by Lugiato et al(1). The experimental observations in CO2 lasers(2,3) have provided clear evidence of the bistability phenomenon and shown that the absorber parameters could be determined from these observations. In this work a quantitative comparison between a theoretical description of optical bistability and the experimental results is presented for the first time. The parameters defining the laser cavity and the CO2 amplifying medium were measured carefully, and the bistability was observed and analyzed quantitatively as a function of the laser parameters.
Periodic window, period doubling, and chaos in a liquid crystal bistable optical device
Authors: Song Jae-Won , Lee Hai-Young , Shin Sang-Yung , Kwon Young-Se
Published: February 2023

A twisted nematic liquid crystal (TNLC) bistable optical device is constructed to study the Feigenbaum scenario1 in a manner of Gibbs et al.2 The simple transmission, having a single near-trapezoidal hump and a non-negligible extinction level, facilitates experimental observation and computer simulation. A number of periodic windows, i.e. 3, 4, 5, and 7T(T means a period), have been easily observed as well as period doublings up to 4T and chaos. It was also confirmed that these waveforms have the 'universal-sequence' patterns reported by Metropolis et al.3 Based on a simple 'broken-linear' modelling of the TNLC modulator transmission characteristics, the computer simulation has been performed to show period doublings, periodic windows, and period mergings. It exhibits reasonably good agreement with the experiment, and explains easy observation of periodic windows.
Effects of the Radial Variation of the Electric Field on Some Instabilities in Lasers and in Optical Bistability.
Authors: Lugiato L.A. , Milani M.
Published: February 2023

In 1966 Haken and Risken, Schmid and Weidlich(1) showed that under proper conditions the stationary state of a homogenously broadened, single mode ring laser can become unstable. The instability requires a "bad cavity" situation, i.e. the cavity damping constant must be larger than the atomic decay rates. Later, Haken(2) proved that such an instability coincides with the well known Lorenz instability, which leads to chaotic behaviour. On the other hand, Risken and Nummedal and independently Graham and Haken(3) analyzed the homogeneously broadened ring laser taking into account all the longitudinal cavity modes. They showed that under appropriate conditions in the good cavity case some cavity modes, different from the one resonant with the atomic system, can become unstable. In this case, one has the formation of a pulse that travels in the cavity. In 1978, Bonifacio and Lugiato(4) showed that a similar self-pulsing behaviour in good cavity conditions occurs in optical bistability in a ring cavity filled with a homogeneously broadened atomic sample.
A Saturable Interferometer Theory of Absorptive Optical Bistability
Authors: Lawandy N. M. , Willner R. P.
Published: February 2023

In this paper we will utilize the method of summing transmitted waves routinely used to analyze interferometer structures to develop an OB equation. The method yields a different state equation than the usual mean-field model. However, for small C values and or large input intensities a Taylor expansion of our state equation yields the mean field pure absorptive OB equation. Our equation also gives a different condition for hysteresis. Due to the simplicity of this approach which utilizes the sum of a geometric series, we are able to interrogate the system after any given number of round trips via the analytic expression for the sum at that point. This allows us to obtain an inverted function of time and to determine the time evolution of the system. Using these expressions, we are able to give switching times for both the up and down processes.
Non-Linear Fabry-Perot Transmission in a CdHgTe Etalon
Authors: Parry G , Hill J R , Miller A
Published: February 2023

We have recently reported the observation of large intensity dependent changes in the refractive index of cadmium mercury telluride at 175K and 10.6 µm [1]. This non-linearity arises because of bandgap saturation, as seen in InSb [2], and through a free carrier, plasma contribution. In contrast to the InSb non-linearity which was modelled, in terms of an "n2I" correction to the linear refractive index (I is the incident intensity), the non-linearity in the narrower bandgap CdHgTe at 175K showed an intensity dependence proportional to I1/3. This was consistent with the dominant Auger recombination process.
Self-Pulsing and Chaos in Inhomogeneously Broadened Single-Mode Lasers
Authors: Graham R. , Cho Y.
Published: February 2023

Homogeneously broadened single mode lasers are well known to exhibit self-pulsing instabilities and chaotic dynamics under the combined conditions of large ratio of gain over losses and low cavity quality. In fact, a homogeneously broadened single mode laser in resonance has essentially 3 degrees of freedom only and is realistically described by the Lorenz model, which has served as a prototype model for investigating chaos in continuous dynamical systems. However, the above mentioned conditions for the occurrence of chaos have not yet been realized, experimentally.
Self-Defocusing and Optical Crosstalk in a Bistable Optical Etalon
Authors: Tai K. , Gibbs H. M. , Moloney J.V. , Tarng S.S. , Jewell J.L. , Weinberger D.A.
Published: February 2023

Self-focusing effects in optical bistable hysteresis loops have been observed in a GaAs-GaAlAs superlattice.1 Experimentally, one sees drastic overshooting in the hysteresis loops and changes in the output profile as the imaging lens is translated along the propagation direction, thus imaging different object planes onto a fixed image plane (i.e. aperture). Nearly identical results are found by a one-transverse-dimension numerical simulation of good-cavity bistability in which the output is free-space propagated backwards in space, corresponding to the movement of the imaging lens. These effects arise from a radially-dependent phase shift caused by the excitonic nonlinear refraction and a gaussian beam profile.
Chaos in Optical Bistability
Authors: Derstine M.W. , Gibbs H.M. , Hopf F.A. , Kaplan D.L.
Published: February 2023

Experiments on chaos in a hybrid optically bistable system with delayed feedback are presented. Special attention is paid to the connection of these experiments to the issue of what chaos is, and why it has recieved such considerable attention in recent years.
Demonstration of a Triple Bistable-Element Loop Circuit for a Digital Parallel All-Optical Computer
Authors: Smith S.D. , Mathew J.G.H. , Taghizadeh M.R. , Tooiey F.A.P. , Walker A.C.
Published: February 2023

An essential feature for any logic gate in an all-optical circuit is cascadibility, ie. the change in output from one device must be of sufficient magnitude to switch the next. We have developed nonlinear interference filters as bistable optical logic gates and have already shown them to be cascadable in simple all-optical digital circuits(1). This paper describes the successful operation of a three-element loop circuit with programmable control of gate bias levels. Such a configuration, extended to arrays of bistable elements, can form the basis of a digital all-optical loop processor.