bluuebunny/crossref_metadata_2025 huggingface dataset:
Dichromatic reflection model and illuminant estimation
Authors: Tominaga Shoji , Wandell Brian A.
Published: February 2023

The dichromatic reflection model is widely used to describe empirical properties of color signals reflected from inhomogeneous materials. This model assumes that light is reflected by two independent mechanisms of the specular (or interface) reflection and the diffuse (or subsurface) reflection. However, there are relatively few experimental results to evaluate the adequacy of the model. We describe new measurements of the spectral power distributions of lights reflected from inhomogeneous objects in a variety of geometric conditions. We use a principal component decomposition of these observed spectra to test the adequacy of the model. If the model is correct, and furthermore the spectral composition of the specular component of light is the same as the spectral composition of the incident light, it is possible to estimate the spectral power distribution of the light from sensor data. We show that the estimation problem is reduced to finding the common spectral information from the measurements from two or more surfaces. From experiments we conclude that the dichromatic model is adequate for describing color signals from some inhomogeneous materials. Furthermore, we present an algorithm for estimating the illuminant spectral power distribution. The feasibility of this estimation is evaluated using several test objects. (12 min)
Estimating reflectance in the presence of shadows and transparent overlays
Authors: Plummer Daniel J. , Kersten Daniel
Published: February 2023

One of the classical problems in visual perception has been to understand the relative constancy of surface color judgments despite spatial and spectral variations in irradiance. One aspect of this problem has to do with the color apearance in achromatic conditions, that is, lightness constancy. Most research in lightness constancy has concentrated on conditions under which the illuminant is either constant or slowly varying in space and usually invisible. In this study, we measured the human ability to estimate the reflectance of mondrian surfaces in the presence of either visible multiplicative illumination or additive veiling overlays with sharp boundaries for both monocular and stereo viewing conditions. It was found that human observers estimate reflectance well with a relatively small bias in the direction of a luminance match.
Percelved complementary colors of computer-generated geometric achromatic figures surrounded by chromatic grid fields
Authors: Mizusawa Kiyoe
Published: February 2023

In both the Hermann and Speillman illusions, small gray spots are seen at the intersections of the white grid on the surrounding black grid field. The existing explanations of the illusions are of two types. The first explanation states that the gray depressed spots are caused by the excitatory regions of the human receptive fields having concentric on-center and off-center areas. Other investigators attribute this phenomenon to Ratliff’s theory on the effect of the secondary bipolar cell innovations. Although the process is not the same as the illusion described above, the present research systematically investigates the perception of the geometric figures consisting of black grids surrounded by high-frequency colored grids. Six different surrounding colored grid figures with five different densities of grid were tested. The subjects perceived a black grid figure as various reflecting colors complementary to the surrounding grid colors. The optimal visual angle for the illusion was 6–18 min of arc. The results were analyzed by the analysis of variance, and a few theoretical implications were discussed by comparing the theories described above.
Reading and color contrast
Authors: Knoblauch Kenneth , Arditi Aries , Szlyk Janet
Published: February 2023

While reading is generally optimal with a high luminance-contrast text, the role of color contrast in reading performance has not been quantitatively studied. We examined the influence of color contrast on the reading rate in normal observers for a range of character sizes spanning those of everyday reading. Text was presented on a CRT either in pages (several lines at once) or scrolled (drifting from right to left) on a white background of 48 cd/m2. Four conditions were examined: (1) high contrast (achromatic); (2) low contrast (achromatic); (3) low contrast (achromatic + chromatic); and (4) near equiluminant (chromatic). Chromatic contrast affected low (~0.12) contrast reading only for the smallest character sizes. This effect, the direction of which depended on the color of the text, could not be accounted for by focus errors to the chromatic stimuli. Reading rates for near equiluminant text (<0.01 contrast) were about half of those for a high-contrast text with medium width characters and worse for smaller characters but were, nevertheless, much higher than those reported by other investigators for the text of comparable luminance contrast in the absence of chromatic contrast.
Strain generated optical nonlinearities in certain II-VI quantum well systems
Authors: Jackson S. A.
Published: February 2023

In a piezoelectric material, strain gives rise to internally generated polarization fields. These electric fields can have profound effects on the optical properties of the material. In a lattice mismatched quantum well or superlattice system, pseudomorphic growth gives rise to strain in the layers. We calculated the lattice mismatch strain generated electric fields in CdTe/CdMnTe quantum wells and ZnTe/ZnMnTe quantum wells. We then calculated the nonlinear susceptibilities χ2 and χ3 in the presence of these fields, which show strong enhancements at certain frequencies. We have also calculated the effect of the strain generated electric fields on tunneling of the carriers between quantum wells. This affects the optical absorption probability.
Saturation of cathodoluminescence from single GaAs/AlGaAs quantum wires
Authors: Weiner J. S. , Pearton S. J. , Dolan G. J. , Watson Ibm T. J. , Dunsmuir J. , Gossard A. C. , English J. E.
Published: February 2023

We observe saturation of cathodoluminescence (CL) from GaAs/AlGaAs single quantum well wires (QWWs) at high excitation intensity. The GaAs/AIGaAs QWWs were fabricated by electron-beam lithography, selective gallium ion implantation, and annealing.1 Single QWWs were excited with a cw or pulsed 5-keV electron beam, and the resulting CL is detected by cw or subnanosecond time-delayed-coincidence photon counting. At 20 K and low excitation intensity the CL spectrum shows a peak at 1.65 eV due to the QWW and a weaker peak at 1.7 eV due to carriers excited in the surrounding implanted material. As the excitation intensity is increased, the lower energy peak broadens on the high-energy side and eventually saturates in intensity at a density of 8 × 1017/cm3, whereas the CL from the implanted or large masked regions saturates at the higher density of 4 × 1018/cm3. We attribute the saturation to band­filling. Time-resolved CL measurements are discussed. We report the first observation of CL from QWWs at room temperature. The CL intensity of the QWWs is comparable with that of the implanted regions. Both are an order of magnitude weaker than that of the unimplanted quantum well.
Analysis of diffraction anomalies due to guided wave excitation in overcoated low-efficiency gratings
Authors: Elson J. M. , DeSandre L. F.
Published: February 2023

An extinction theorem analysis is applied to calculate diffraction efficiency of multilayer over­coated low-efficiency gratings. The nominal efficiency of the –1 order, for example, may be 1-2%. However, in certain resonance conditions, the efficiency may jump to as much as 50 % with a corresponding reduction in the specular beam. Numerous numerical examples are presented. These include replicating and nonreplicating interface profiles. The nonreplicating examples may be a gradually varying shape from interface to interface or several planar interfaces and the profile at a single interface. The incident beam may be either a plane wave or a Gaussian. The effect of guided wave resonance on the reflected beam is presented.
Diffraction theory of interference coatings
Authors: Carniglia Charles K.
Published: February 2023

The question sometimes arises as to whether an interference filter affects the shape or the direction of propagation of a reflected or transmitted beam. The answer can be found by expressing the incident beam (which is assumed to be spatially and temporally coherent) in terms of its spectrum of angular plane wave components. The amplitude reflectance and transmittance of the filter act on each plane wave, and the shape and direction of the reflected and transmitted beams can be determined from the composite of all the waves. A 2-D theory is employed, and several elementary results are obtained. In particular, in regions of slowly varying reflectance amplitude, the derivative of the phase of the reflectance with respect to incident angle in related to a lateral translation of the reflected beam. The second derivative of the phase with respect to angle corresponds to a shift in focus of the reflected beam. The results for reflectors and narrow bandpass filters are presented. The theory is also consistent with the behavior observed in the case of wave guiding structures and surface plasmons.
Digital beam steering system using modules of ferroelectric liquid crystal and Wollaston prism
Authors: Karim M. A. , Cook D. , McManamon P. F.
Published: February 2023

A digital beam steering system is designed using a contiguous stack of multiple modules each consisting of a fast-responding ferroelectric liquid crystal (FLC) layer and a Wollaston prism. The FLC layer is organized to provide a halfwave retardation, which in combination with the Wollaston prism ensures a predetermined angular deflection, which in turn depends on the thickness, refractive indices, wavelength, and split angle of the prism. With each succeeding module designed to yield an angular beam deflection of 2
m
–1 x rad, where m is the number of module and x is the angular deflection of the first module, the total system can be designed to have high resolution, fast response, and good pointing accuracy. The problems such as those of ray walk-off, aperture adjustments, and imperfect addition of angles are considered in detail in designing the complete system.
Optical properties of ferroelectric smectic C* during the unwinding by means of a magnetic field
Authors: Benguigui L. , Abdulhalim I.
Published: February 2023

We present a theoretical study of the optical properties of a ferroelectric SmC* liquid crystal during the unwinding by an external magnetic field perpendicular to the helix axis. We used the 4 × 4 characteristic matrix method to calculate the selective reflection. Contrary to the case of the cholesteric, the unwinding process is not unique, but depends on the temperature. We present the results in the two following cases: very near Tc (the SmA–SmC* transition temperature) and far from Tc, for which analytic solutions exist.
Computer-generated holography using a high-resolution laser writer
Authors: Baber S. Charles
Published: February 2023

The Computer Imaging Branch of the Corporate Manufacturing Center at Texas Instruments has designed and built high-speed high-resolution laser writing systems since 1982. These systems have a range of effective pixel size from 10 down to 0.5 μm, with writing rates as high as 100 Mpixels/s. Although originally designed for circuit board and photomask application, these systems are well suited for the plotting of computer-generated holograms. Recently, an internal program was initiated to investigate the application of computer-generated holograms for the testing of diamond point turned aspheric optics. This presentation focuses on the description of our laser writers, the methods by which the holograms are computed from CO­DEV (TM) polynomial representations, and the results using the binary holograms for testing as-pheres.
Array generation with multilevel phase gratings
Authors: Walker Susan J. , Jahns Jurgen
Published: February 2023

Computer-generated gratings which produce a number of equal intensity diffraction orders have been of interest recently for various applications. One application is the distribution of light energy on 2-D arrays of optical logic devices in an optical computer. Different schemes to achieve high uniformity and high efficiency have been investigated. Our approach is an extension of Dammann’s theory of binary diffraction gratings.1 An increase in afficiency can be obtained by using more than two phase levels. Gratings were fabricated using quartz glass substrates and reactive ion etching techniques. We present a theory of multilevel phase gratings as array generators and show experimental results. The performance of binary and multilevel phase gratings is compared.
Encoding method for high-efficiency multiple-beam holograms using simulated annealing
Authors: Feldman Michael R. , Guest Clark C.
Published: February 2023

We have developed an iterative algorithm for generating the transmittance function of binary onaxis holograms. The hologram is divided into rectangular cells so that each cell imparts a phase delay of 0 or ϕ rad on the incident wavefront. An iterative optimization routine based on simulated annealing is used to determine (1) the binary state of each cell and (2) the value of the phase difference ϕ between cells of different states. The algorithm is similar to the direct binary search encoding method.1 In particular, this encoding method was applied to the design of multiple-beam holograms or holograms designed to reconstruct an M × N array of equally bright spots centered on the z axis. The encoding algorithm maximizes the diffraction efficiency for a specified allowed variance in intensity among the M × N signal spots. In addition the CGH transmittance pattern can be designed to compensate for phase mismatch problems (variations in the phase delay ϕ from the specified value due to fabrication process tolerances) at the expense of a reduction in diffraction efficiency and/or signal power errors. Theoretical results indicate that binary HOEs with diffraction efficiencies larger than 70% are possible. An experimentally fabricated hologram reconstructed a 3 × 3 array of spots with a diffraction efficiency of 59% and with less than a ±10% deviation in spot signal powers.
Estimation of aerosol optical properties from the Inversion of extinction measurements
Authors: Chu W. P.
Published: February 2023

This paper deals with the problem of estimating the optical properties of aerosols based on a finite number of extinction measurements. This kind of problem arises in many situations involving the remote sensing of aerosols with optical instrumentation such as radiometers for extinction measurements and lidar systems for backscattering measurements. A technique has been developed so that extinction measurements at a finite number of spectral regions can be inverted directly to yield either extinction or backscattering values at other wavelength regions without solving for the aerosol size distribution function. This technique is based on the inversion method developed by Backus and Gilbert. The approach has been successfully used in the retrieval algorithm for the SAGE II satellite measurements of aerosol and ozone vertical profiles. Extension of this method to the conversion of extinction measurements into backscattering values has been applied to the comparison of SAGE II aerosol extinction data with coincident lidar backscattering measurements.
Internal fields of two cooperatively scattering spheres
Authors: Fuller K. A.
Published: February 2023

A study is made of the fields that arise at points interior to a pair of spheres that cooperatively scatter electromagnetic radiation. These bispheres are composed of spheres ranging in diameter from about one to ten wavelengths of the incident radiation, and the effects of various orientations of the pair with respect to that radiation are discussed. The structure of the internal fields under resonant and nonresonant conditions is examined for refractive indices ranging from 1.3 to 2.0. The center-to-center separation between the spheres is allowed to vary from the sum of their radii to ~100 radii. This study is a theoretical treatment of the problem, and two methods are utilized. One treats the bisphere as a single particle and involves matrix inversion, whereas the other technique casts the problem into an order-of-scattering context and thereby obviates matrix inversion. This latter procedure has only recently been applied to the problem of cooperative scattering by two or more spheres and, in essence, decomposes the scattered field of the bisphere into discrete interactions between fundamental constituents. The contribution of specific orders of scattering to the construction of the internal fields is considered where appropriate.
Diffractive optical element for an optical servo system
Authors: Mokry Patricia A.
Published: February 2023

An embossed diffractive optical element (DOE) is used as an efficient planar inexpensive collimator for a point source light-emitting diode. The DOE, with a 1-mm diameter and 2.1-mm focal length, is installed in a 2.5-mm square read/write head on-axis with an 890-nm LED. This collimated beam emits through a magnetic-coated floppy disk, which includes a transmission diffraction grating, the grating pitch corresponding to the magnetic track width. A similar head on the opposite side contains a photodetector etched with lines of the same grating pitch. The detector output signal obtained provides a position error signal. This paper discusses the design, fabrication, testing, measurement, and operation of the diffractive optical element in this device. Throughput efficiency of >25%, full angle divergence of <1 mrad, and cross-sectional analysis featuring <3-μm linewidths are presented. Signal data obtained using the DOE are compared with that from a molded plastic collimating lens. In addition, results using the DOE with other light sources, such as red LEDs and laser diodes, are discussed.
Human ocular melanin assessed by imaging fundus reflectometry
Authors: Kilbride Paul E. , Pori Kathleen M. , Alexander Kenneth R.
Published: February 2023

Because of the possible role of melanin in various ocular pathologies, it is important to develop a noninvasive objective measurement of this ocular pigment. We have used imaging fundus reflectometry to assess the spatial distribution of melanin within the macular region. A microchannel plate-intensifier solid-state video camera viewed an area of the fundus (21° horizontally by 16° vertically) through the optics of a modified Zeiss fundus camera. A fiber-optic lightguide illuminated by a computer-controlled optical system replaced the normal Zeiss light source. Images of the unbleached and bleached fundus were obtained at thirteen wavelengths (460-700 nm). For the present study, digitally processed images of the bleached fundus obtained at long wavelengths (>620 nm) were used to provide an estimate of the spatial distribution of melanin in the macular region. In three Caucasian subjects, our measurements show a region of lower reflectance in these long wavelengths that is ~10° in diameter and centered on the fovea. This result is consistent with previous anatomic studies reporting that the melanin optical density is higher in the central macula than in the surrounding region.
Automated retinal image matching by segmentation
Authors: Nutter Brian S. , Mitra Sunanda
Published: February 2023

Spectral characterization of retinal images is a complex task because of the superimposed blood vessels in the retinal photographs. We have developed a segmentation technique based on a combination of edge detection and optimal thresholding operations so that the blood vessel structure can be removed from the retinal texture. The blood vessel removal method includes edge detection, tracing, and replacement with gray levels closely approximating the behavior of the background. The edge detection uses the (unsigned) first derivative of the image. The tracing routine is controlled by a mouse and follows the crests of the first derivative to trace out a length of edge. When the blood vessels are outlined, a search pattern based on finding a dark feature of given width in a light background locates those pixel elements that are clearly blood vessels. When the blood vessels are removed, they are replaced by a close approximation of the background. After the end point grey levels are determined, the vessel is painted over with a linear replacement operation, matching the background at both sides of the vessel. Spectral characterization and matching of the retinal texture can then be performed for automated detection of textural changes.
Three-dimensional measurement of the cornea
Authors: Zhuang Songlin , Xu Yiazhong
Published: February 2023

We propose a new optical method for measuring a 3-D profile of the cornea.
Observation of spatial ringing and internal beam fission in cw pumped pink ruby
Authors: Afzal Sohrab , Lawandy N. M.
Published: February 2023

Self-focusing and spatial ring formation have been predicted in strongly absorbing media of two-level atoms. The requirement for observation of this effect is that the absorption-length product must be greater than the ratio of the input intensity to the saturation intensity and both greater than unity. We have observed a spatial ring formation of an argon-ion laser beam traversing a sample of pink ruby pumped above resonance. In addition, we observed the development of on-axis nulls in the intensity profile. Experiments were also performed on the low-frequency side of the line with a rhodamine 6G dye laser. Ruby is a three-level system that can be modeled as a two-level system with a low saturation intensity because of the long lifetime of the Kramers doublet. The ruby sample was 7 cm long with an absorption coefficient of 0.75 cm−1. With an input intensity of 1 kW/cm2 we are ~2.5 times the saturation intensity of ruby, thereby satisfying both conditions where a spatial ring formation would be expected. We also observed intensity-dependent beam fission leading to an off-axis beam that tracked the c axis and was of the opposite polarization of the main beam. Experiments performed on a 1-cm sample of ruby exhibited no rings, and a second beam was not observed confirming the predicted conditions and excluding any interface effects.
Laser beam combining in atomic potassium vapor
Authors: Gruneisen Mark T. , MacDonald Kenneth R. , Boyd Robert W. , Harter Donald J.
Published: February 2023

When an atomic vapor interacts with an intense nearly resonant laser field, the ac Stark effect causes a profound modification of the weak-field absorption spectrum. Two of the induced spectral features can lead to amplification of a weak probe wave. We have previously measured in atomic sodium vapor high probe-wave gain (G = 38) due to the three-photon effect and a somewhat lower gain (G = 4) when the probe wave is detuned from the pump laser frequency by the inverse of the atomic response time.1 We present the results of an experimental and theoretical study of the energy coupling between two intense laser fields of comparable intensity through their interaction with an atomic vapor. In our experiments, a tunable alexandrite laser provides microsecond laser pulses of the required intensity that are nearly resonant with the 4s → 4p transition in potassium. We observed large energy transfer (50%) between the two waves at the nearly degenerate resonance and measured the intensity dependence of the coupling efficiency. Theoretical modeling of the interaction is based on a continued-fraction solution of the density-matrix equations of motion.
Effects of propagation on three-wave mixing spectroscopy
Authors: Guo Dandan , Sargent Murray
Published: February 2023

We study unidirectional three-wave spectroscopy for which one pump and two probe waves beat in a nonlinear medium at the frequencies ±Δ with respect to the pump. Field transmission spectra change as the fields propagate through the medium due to probe variations in both amplitude and phase. In a homogeneously broadened two-level system, the rates of change in sidemode amplitudes and phases are determined by the effectiveness of the population pulsations in coupling the fields. For cases in which the population difference lifetime T1 is comparable with the dipole lifetime T2, the strong coupling between the sidemodes and the pump leads to fast amplitude change, while strong coupling between the two sidemodes leads to fast phase change. When the pump Rabi flopping frequency Ω ≅ Δ and Δ ≅ 1/T1, the population pulsations couple the two sidemodes most efficiently, causing the sidemode phases relative to the pump phase to vary rapidly. When Ω ≅ 2Δ, the pump field scatters strongly off the population pulsations, thereby amplifying the sidemode fields. When Ω ≫ Δ, the population pulsations become too weak to couple the fields significantly, and phase, amplitude, and spectral features in general change very slowly.
On the transmission of optical pulses across a linear nondispersive/nonlinear dispersive Interface
Authors: Banerjee Partha P. , Chatterjee Monish R.
Published: February 2023

In a recent investigation, cw transmission through a linear nondispersive/nonlinear dispersive interface was studied using the nonlinear Klein-Gordon equation to model the latter medium. It was found that transmission in the nonlinear dispersive region is determined not only by the linear cutoff frequency but also by the transmitted wave amplitudes. The effective propagation constant and the transmission coefficient were evaluated; propagation and nonpropagation mode solutions were obtained, and their stabilities were studied. In this work, we generalize the cw case to include the effects of discrete and a continuum of sidebands around the carrier. The cubic nonlinearity is responsible for the coupling between the ' upper and the lower sidebands. The transmission coefficient and propagation constant are calculated as a function of the sideband and carrier frequencies and their amplitudes. Propagation and nonpropagation modes are also classified.
Transverse Solitary Waves in a Dispersive Ring Bistable Cavity Containing a Saturable Nonlinearity
Authors: Moloney J.V. , Newell A.C. , McLaughlin D.W.
Published: February 2023

Stationary and nonstationary solitary waves can gradually evolve when the incident Gaussian beam intensity exceeds threshold for switching to the high transmission branch of a ring bistable cavity. The number of transverse solitary waves scales as the square root of effective Fresnel number and as the incident laser amplitude.
Observation of Optical Hysteresis in an all optical passive ring cavity
Authors: Harrison R.G. , Emshary C. , Al-Saidi I.
Published: February 2023

We report the first observation of dispersive optical hysteresis in an all optical passive uni-directional ring cavity system. Ammonia gas is used as the non-linear medium for which a number of vibrational-rotational transitions (1) are in near coincidence with the step tunable emission from a TEA CO2 laser. Pronounced instabilities and optical hysteresis are found to occur over a gas pressure range commensurate with that for self-focussing A grating tunable hybrid TEA CO2 laser with amplifier, operating on a single mode, with a gain switched pulse duration of ~ 100 nsec was used. The laser output, sampled via a beam splitter, was coupled through a Ge flat (R = 36%) which formed one element of the three element ring cavity (cavity length ~ 3.5 m) comprising two plane mirrors and incorporating a 1 m long gas cell and beam splitter for sampling the cavity signal. Signals were recorded using photon drag detectors in conjunction with Tektronix 7904/7104 oscilloscopes.
Absorptive Optical Bistability in a bad cavity
Authors: Mandel Paul , Erneux T.
Published: February 2023

In a theoretical discussion of optical bistability, it is often necessary to resort to some approximation scheme to discuss time-dependent properties. The standard method consists in assuming a very good cavity (κ«γ⊥, γ11) Or a very bad cavity (γ11 <<κ1, γ⊥ ) and to perform an adiabatic elimihation of the fast varying variables. In the good cavity limit /1/ the atomic variables are eliminated and one is left with an equation for the field. In the bad cavity limit /2/ the field and the atomic polarization are eliminated and one is left with an eouation for the atomic inversion.
Critical Slowing Down and Magnetically-Induced Self-Pulsing in a Sodium-Filled Fabry-Perot Resonator
Authors: Mlynek J. , Mitschke F. , Lange W.
Published: February 2023

We report on the observation of critical slowing down and of self-pulsing in a Fabry-Perot resonator (FP) filled with sodium atoms under conditions of transverse optical pumping /1/. The experimental set-up (see Fig.1) is similar to the one used in steady-state bistability studies reported before /2/. The dye laser, optically isolated from the FP by means of a Faraday rotator (FR) is detuned from the Na D1-line by 10 to 20 GHz. The sodium sample (N ≃ 1013 cm–3, buffer gas: argon, p=200 mbar) is placed in a near confocal Fabry-Perot (Beam waist: 1 20 μm) and can be subjected to a transverse magnetic field B. The intensity of the laser beam can be switched by means of an electro-optic modulator(EOM), thus providing input-steps of variable height (power:5 – 50 mW). A polarizer P1 is used to either circularly or linearly polarize the input beam. The right– and left circular polarization components of the resonator output beam can be separated by means of a λ/4-plate and a polarizing beam splitter P2. A pair of photodiodes PDi is used for detection.
Multistability due to the helical optical distributed feedback in the cholesteric liquid crystals
Authors: Kukhtarev N.V.
Published: February 2023

It is shown that optical helical distributed feedback may cause the appearence of the multistability in transmission and reflection of the laser light by the cholesteric liquid crystal (CLG) (where helical distributed feedback laser was proposed /1/ and realized /2/) show that multistability may be realized with the intensities 1 kW/cm2 with response time 10–9 sec.
Bistable Injection Lasers
Authors: Harder Ch. , Lau K. Y. , Yariv A.
Published: February 2023

Semiconductor lasers with inhomogeneous current injection have been proposed nearly twenty years ago [1] as highly compact and efficient bistable devices. Recently, we demonstrated that a semiconductor laser with a segmented contact, as shown in Fig. 1, displays bistability without pulsations. The key to the proper design of such a bistable laser is the electrical isolation between the two segments which requires that the parasitic resistance (Rp in Fig. 2) between the two contacts be as large as possible. This can be achieved by doping the top cladding layer only slightly p-type.
Radiation Pressure Induced Optical Bistability
Authors: Dorsel A. , Meystre P. , Vignes E. , Walther H.
Published: February 2023

Over the last few years optical bistability has been predicted and/or observed in a number of configurations involving a nonlinear medium placed inside an interferometer and irradiated by a laser field1.
Advances in GaAs Bistable Optical Devices
Authors: Jewell J.L. , Tarng S.S. , Gibbs H.M. , Tai K. , Weinberger D.A. , Gossard A.C. , McCall S.L. , Passner A. , Venkatesan T.N.C. , Wiegmann W.
Published: February 2023

Bistable Optical Devices (BOD’s) using GaAs as the nonlinear medium are viable candidates for the achievement of fast (⩽ ns), room temperature,1 low-power (mW), externally controllable2 optical switches which are easily fabricated3 and operated. Advances have been made in all of these areas and efforts are in progress to improve performances in ways that are simultaneously compatible.
Zeeman Coherence Effects in Absorptive Polarization Bistability
Authors: Agrawal Govind P.
Published: February 2023

The phenomenon of optical bistability is usually treated within the framework of a single optical mode interacting with a two-level system. Recently, a number of authors1-5 have considered the two-mode case where the mode coupling gives rise to new interesting features such as optical tristability.2 In a specific case of particular interest, the coupling between orthogonally circular polarized modes arises from a two-photon resonance of the Zeeman sublevels.2,5 Bistability or tristability is then observed in the polarization characteristics of a single optical beam. Although Zeeman coherence effects are expected to play an important role, these have usually been neglected in a theoretical description of polarization bistability.2,4
Effect of Driving Laser Fluctuations on Optical Bistability
Authors: Willis Charles R.
Published: February 2023

We derive and analyze the master equation for absorptive and dispersive optical bistability in the high-Q cavity limit where the driving laser has both amplitude and phase fluctuations which are larger than the small amplitude and phase fluctuations caused by incoherent spontaneous emission in the cavity. We treat the amplitude and phase fluctuations of the driving laser as independent time dependent Gaussian processes. The causes of jitter and amplitude fluctuations will vary from laser to laser and the fluctuations need not be Gaussian. However, we use Gaussian processes for mathematical tractability and because we expect them to be qualitatively correct. Recently,1 we have shown in the case of absorptive optical bistability when the driving laser has phase fluctuations the fundamental process which determines the statistical properties of the internal field is the competition between locking of the internal field phase to the phase of the driving laser and the diffusion of the phase of the internal field as a consequence of the driving laser fluctuations. The driving laser fluctuations have little effect if the phase locking rate is larger than the phase diffusion rate caused by the driving laser’s fluctuations. However, when the diffusion rate becomes comparable to the locking rate we find the amplitude of the 2 internal field is reduced and the dimensionless parameter2 measuring the importance of transitions from one branch of the OB curve to the other due to fluctuations takes on a value which leads to an appreciable transition rate due to fluctuations.
Optical Bistability in Nonlinear Media: An Exact Method of Calculation
Authors: Band Y.B.
Published: February 2023

In a recent paper1 I formulated a method for calculating propagation through nonlinear media for a number of nonlinear optical phenomena. This method does not use the SVEA and can therefore solve nonlinear propagation problems when refraction and reflection at the boundary interfaces are important. Here, I report the first calculation using this exact (albeit numerical) method. For this first test of the utility of the method, I have chosen to study optical bistability in a thin film whose index of refraction is intensity dependent.
Multi-parameter universal route to chaos in a Fabry-Perot resonator
Authors: Abraham E. , Firth W.J.
Published: February 2023

We recently reported [1] preliminary investigations of positive-branch instabilities in nonlinear resonators in the Fabry-Perot (folded) configuration. We deal with the dispersive limit of the Maxwell-Bloch equations (Kerr medium). The finite longitudinal relaxation time (τ) means that diffusion of the excitation is possible, and we assume that the diffusion length greatly exceeds the wavelength.
Switching Behavior of Bistable Resonators Filled with Two-Level Atoms
Authors: Chang E. , Cooperman G. , Dagenais M. , Winful H.
Published: February 2023

A comprehensive numerical and analytical study of the switching dynamics of bistable optical devices is reported. The intracavity medium is modelled as an ensemble of two-level atoms which may be either homogeneously or inhomogeneously broadened. By allowing for arbitrary atomic detunings and cavity mistunings, both the absorptive and dispersive contributions to optical bistability are included. Standing waves are fully taken into account in the usual way through Fourier expansions.
Optical Bistability in Four-Level Nonradiative Dyes
Authors: Zhu Zhen Fu , Garmire E.
Published: February 2023

Most saturably absorbing dyes show a large unstaturable loss which removes the possibility of purely absorptive bistability. However, nonradiative dyes such as those used for Q-switching have an intensity-dependent phase shift which may allow bistability. We will show that this nonlinear refractive index comes from the population redistribution during saturable absorption.
Bistability in Optical Waveguides
Authors: Sibilia C. , Bertolotti M.
Published: February 2023

Using a treatment due to Bendow, Gianino and Tzoar (1) in which the electric field of a cw gaussian beam in a nonlinear waveguide is given utilizing the paraxial approximation, it is shown that a bistable behavior can occur in a cylindrically simmetric nonlinear waveguide in which the dielectric constant has a parabolic behavior in the radial direction.
The NMR Laser - A Nonlinear Solid State System Showing Chaos
Authors: Brun E. , Derighetti B. , Holzner R. , Meier D.
Published: February 2023

Pathways from simple to complex behavior of nonlinear systems is a topic of intense theoretical and experimental interest after J.M. Feigenbaum, J.P. Eckmann and others have demonstrated universal features of a sequence of period-doubling bifurcations leading to chaotic states.
Optical Nonlinearity and Bistability due to the Biexciton Two-Photon Resonance in CuCI
Authors: Peyghambarian N. , Sarid D. , Gibbs H. M.
Published: February 2023

It is well established that biexcitons can be generated directly by two-photon absorption in CuCI. The intensity dependent nonlinearity arising from this resonance can be used to obtain optical bistability. Recently, Koch and Haug(1) and also Hanamura(2) have predicted the possibility of a bistable operation in a CuCI Fabry-Perot etalon. Hanamura uses a density matrix formalism and predicts that the switching can respond in a picosecond time scale due to the virtual formation of biexcitons. Koch and Haug obtain the complex dielectric function from a Green's function formalism and suggest a bistable behavior for a thin CuCI slab. They use a constant value for the biexciton linewidth, γxx, and a zero value for the exciton linewidth, γx. Their results indicate that a 1-μm-thick CuCI etalon, with natural reflecting surfaces, can give rise to bistability with a switch-on intensity of about 0.1 MW/cm2. The biexciton resonance, however, is located on the tail of the exciton resonance, which acts as a background absorption.
Optical extinction theorem theory of optical multi-stability bifurcations and turbulence in the Fabry-Perot interferometer
Authors: Bullough R.K. , Hassan S.S. , Hildred G.P. , Puri R.R.
Published: February 2023

We have reported two different aspects of this work already [1,2]. Nevertheless as the point of view is unconventional we review it here strictly within the context of the theory of optical bistability and optical multistability. We are concerned to connect the envelope Maxwel1-Bloch equations with optical bistability (multistability) in a Fabry-Perot (FP) cavity in a rigorous and potentially quantitative way. One problem in this connection is an adequate statement about standing waves. We present methods which derive the standing wave equations of motion completely as a part of a comprehensive non-linear refractive index theory of multistabi1ity inside the FP cavity. The theory is a c-number one — but a comparable quantum theory seems possible. A key feature of the argument is generalisation of the famous 'optical extinction theorem' [1,2,3] to this non-linear regime. In practice it means we do not invoke any boundary conditions at the surfaces of the FP cavity — only conditions at infinity — and this offers advantages for the quantitative description as we show.
Optical Bistability from the Dicke Model
Authors: Puri R.R. , Hildred G.P. , Hassan S.S. , Bullough R.K.
Published: February 2023

We have reported a fairly complete analysis of the quantum Dicke model [1]. This consists of N 2-level atoms on the same site driven by arbitrary fields - coherent, chaotic, mixed coherent-chaotic. We also showed [2] in particular that it is easy to include, albeit in a rather formal way, the effects of a cavity on the Dicke model in abroad band chaotic field. The results agree well with those recently observed on high Rydberg Na atoms [3]. This suggests that a comparable analysis for a coherent driving field which also includes the effects of a cavity will provide a quantum theory of optical bistability. It also suggests that some of the consequences of the theory, primarily photon statistical properties, which, however, are calculated as interatomic correlations [2,3], might be observable in a suitable experiment.
Routes to Optical Turbulence in a Dispersive Ring Bistable Cavity Containing Saturable Nonlinearities
Authors: Moloney J.V. , Gibbs H.M. , Hopf F.A.
Published: February 2023

The transition to turbulence in fluid dynamical systems involves many different pathways depending on parameters such as the Reynolds number, aspect ratio of the fluid, etc. Remarkable progress has been made over the past 10 years in understanding qualitatively, transitions to low level turbulence in low aspect ratio, low Reynolds number systems by studying mappings of one and two dimensional nonlinear functions.1 However no quantitative relation appears to exist between fluid parameters (Reynolds #, Prandtl # etc.) and the parameters appearing in the mappings.
Optical hysteresis and bistability in the wave-front conjugation by electrooptic crystals
Authors: Kukhtarev N.V. , Semenets T.I. , Starkov V.N.
Published: February 2023

Analitical and numerical investigation of the wave-front conjugation in electrooptic crystals (LiNbO3, BaTiO3, SBN) show that noncavity optical bistability and hysteresis /1,2/ depends on the dominant mechanism of nonlinear responce (diffusion or drift) as on the orientation of the crystal C axis, and is strongly influensed by absorption or gain. Calculation show that critical effects may be observed for crystal length 0.1 cm (SBN, BaTiO3) and 1.5 cm (LiNbO3) for the optimal experimental geometry.
Nonlinear Optical Response of the Lowest Exciton Resonances in GaAs
Authors: Ulbrich R. G.
Published: February 2023

Summary not available.
Chaos in Dispersive Bistability
Authors: Schenzle Axel
Published: February 2023

Summary not available
The Physical Mechanism of Optical Instabilities
Authors: Silberberg Yaron , Bar-Joseph Israel
Published: February 2023

Nonlinear optical systems can transform a continuous wave input beam, if it is intense enough, into an oscillating light output. The system which has been most thoroughly studied is an optical resonator, usually of the ring type, containing either a Kerr medium1,2 or a two-level medium. Unfortunately, the mathematical approaches of these studies do not lend themselves to a tractable intuitive explanation of the self-pulsation phenomena, and do not identify the physical origin of instabilities. In this paper we consider a different approach, showing that optical instabilities stem from one source, namely, gain generated by four-wave mixing processes. This gain, together with feedback supplied by the resonator, leads to oscillation of sidebands of the input field. The beating between these sidebands and the input field causes the oscillating output intensity. The salient feature of our approach lies in its intuitive appeal, namely, it is possible to predict the behavior of the system for a wide range of parameters. Moreover, our model enables understanding of the system's evolvement beyond the first bifurcation, something usually not possible with the other approaches.
Connection between Ikeda instability and phase conjugation
Authors: Firth W J , Wright E M , Cummins E J D
Published: February 2023

Period-doubling to chaos (1) and phase conjugation are two nonlinear optical phenomena which have attracted enormous but largely independent interest in recent years. In this paper we establish a close connection between the two phenomena, both being forms of near-degenerate four-wave mixing.
Critical Quantum Fluctuations in Optical Bistability
Authors: Drummond Peter D.
Published: February 2023

Intrinsic optical bistable elements that have been investigated to date typically are either high-Q devices dominated by the interferometer relaxation, or else are fast switching devices dominated by relatively slow population transfers. In the case of the one-mode quantum theory of optical bistability with two-level atoms, these limits can be treated in a unified way with a single Fokker-Planck equation.
Fluctuations in Optical Bistability: Experiment with Shot Noise
Authors: McCall S. L. , Ovadia S. , Gibbs H. M. , Hopf F. A. , Kaplan D. L.
Published: February 2023

The behavior of an optical bistable system in which the fluctuations play the dominant role has been studied on the basis of a Fokker-Planck description by Schenzle and Brand.1 However, all the analyses so far approximate the fluctuations as arising from a constant external noise source described by a δ-correlated, Gaussian random process.2,3 In this paper intensity-dependent shot noise fluctuations of a bistable system are experimentally studied for the first time, using a hybrid bistable optical device, and analyzed by a simple “ladder" model that fits the data well.
Optical Bistability, Chaos in the Coherent Two Photon Processes:
Authors: Agarwal G.S. , Singh Surendra
Published: February 2023

The cooperative behavior of a system of atoms contained in a ring cavity is investigated under the condition that the fundamental atomic transition is a two photon transition1. Maxwell-Block equations are used to obtain the input vs. output relation by adiabatically eliminating all the atomic variables. The fundamental equation that results is a complex two dimensional map--which in the mean field limit reduces to the standard bistability equations. The characteristics of the two dimensional map are numerically investigated. Such a map is shown to lead to chaotic behavior following the Feigenbaum2 scenario. The sequence of events following first regime of chaos is a set of period halving bifurcations. The characteristics of the power spectrum in the region of chaos are presented. The effect of noise on the period doubling bifurcations in the present model, is also investigated and the connection with the theoretical predictions3 is established. The changes in the dynamical characteristics of the system when atomic inversion relaxes on the same time scale as the cavity round trip time will also be discussed in detail.
Turbulence and 1/F Noise in Quantum Optics
Authors: Arecchi F. T.
Published: February 2023

An exciting chapter of physics has been the study of fluctuations and coherence in lasers: how atoms or molecules, rather than radiating e.m. field independently, decide to "cooperate" to a single coherent field; then, for still higher excitation, how and why they organize in a complex pattern of space and time domains, with small correlations with one another (optical turbulence). Here we discuss these new features of quantum optical systems.