bluuebunny/crossref_metadata_2025 huggingface dataset:
Multistability, self-Oscillation and Chaos in Nonlinear Optics
Authors: Carmichael H.J. , Savage C.M. , Walls D.F.
Published: February 2023

We describe a system comprising two circularly polarized ring-cavity modes coupled via a J=½ to J=½ transition. Both modes are equally excited by a linearly polarized incident laser. The steady-state transmission of the cavity shows optical tristability and polarization switching as predicted by Kitano et al.(1) and recently observed.(2) We generalise the model of Kitano et al. with the inclusion of saturation and absorption. In addition to optical tristability we find quadrastability (four stable output configurations for the same input intensity), self-oscillation, and chaos.(3) We have studied the chaotic region numerically as the incident laser intensity and the detuning of the cavity modes is varied. The routes to chaos appear to be analogous to those in the Lorenz equations. For a decreasing incident intensity the passage to chaos involves a new period doubling sequence of periodic windows embedded in chaos, where in each periodic window conventional period-doubling of the Feigenbaum type is observed. We have estimated the experimental parameters required to observe chaos in this system and find that power requirements are modest, although the limitations imposed by the adiabatic elimination and single-mode assumptions used in our theory cause some difficulties -- chaos may well remain, however, when these theoretical restrictions are relaxed.
Non-linear Optical Associative Memories
Authors: Psaltis Demetri
Published: February 2023

A class of associative memories involving global linear transformations, local non-linearities and feedback will be discussed. The general structure of an optical memory of this type is shown in Figure 1. It consists of two major components: An optical system, lumped as a volume holographic element in the figure, and a two dimensional array of optical threshold units. The volume hologram provides global communication to the threshold elements through the optical feedback path. Information is stored in the optical interconnection network and the threshold elements provide access to the optical memory by associative addressing.
Fast All-Optical Switching at Extremely Low-Switching Energy in CdS Platelets
Authors: Dagenais M. , Sharfin W.F.
Published: February 2023

Using a laser slightly detuned from the I2 bound exciton resonance in CdS, we report the observation of the lowest switching energy (< 4 pJ) for an all-optical bistable device. The deconvoluted switching-on and -off times are evaluated to be less than 1 and 2 ns respectively. Even shorter switching times are expected, and we are presently improving our time resolution. Forward, degenerate four-wave mixing experiments were also performed near the I2 bound exciton, an exciton bound to a neutral donor. A four-wave mixing signal was observed with less than 50 W/cm2 incident on the sample.
Room Temperature Optical Nonlinearities and Bistability in CdHgTe and CdTe
Authors: Miller A , Craig D , Steward G
Published: February 2023

Semiconductors offer great promise as compact bistable elements for optical signal processing applications because of their strong interactions with laser light but the question of optimum material choice remains. The largest electronic nonlinearities are found in narrow gap semiconductors, while thermally induced nonlinearities in large gap materials would seem to be attractive for parallel processing.
White Light Switching of Visible Nonlinear Interference Filters and its Implications for the Design of a Spatial Light Modulator
Authors: Taghizadeh M.R. , Tooley F.A.P. , Mathew J.G.H.
Published: February 2023

Interest has been expressed in the development of a novel solid-state spatial light modulator (SLM) based on switching of arrays of intrinsic (ie all-optical) bistable elements. Our recent success in the demonstration of low-power optical bistability in thin film nonlinear interference filters using visible radiation suggests that they are attractive candidates for this role. The filters have the additional advantage of long-term steady state operation.
Dynamic gain of an optical transistor
Authors: Nardone P. , Mandel Paul
Published: February 2023

We study the semiclassical mean field limit equations describing an optical transistor in the case of dominant dispersive optical bistability/1/ where n is the field-induced refraction index, I the input intensity and θ the field-cavity detuning. All variables are scaled.
Dynamic Bistability in Parametric Resonance in Crystals
Authors: Gadomski W. , Ratajska-Gadomska B.
Published: February 2023

The bistable parametric resonance occurs in a crystal interacting with a biharmonic optical field if the difference between optical frequencies equals twice the vibrational frequency of a lattice mode [1,2].The square of the amplitude of the lattice vibrations, a, is resonantly enhanced and exhibits bistable behaviour with respect to both the difference frequency and the field amplitudes E and E'. The stationary dependence of a on E has the form of the unfoldings of pitchfork bifurcation [3], corresponding to different values of E' (Eig.1a). Although the pitchfork branches are separated we demonstrate the complex hysteresis loops linking those branches together (Fig.1b).
Optical Multistability and Oscillations in Hybrid Optical Bistable Systems with Short Delay Times
Authors: Muriel M.A. , Martin-Pereda J.A.
Published: February 2023

In a previous paper1an empirical and analytical study of instabilities in hybrid optical bistable systems was reported by us. At the end of that paper and in order to study the theory, a triangular voltage bias was added to the feedback, instead of the usual constant one. In that way the workline is displayed with the same slope, tg−1βIIN. Because the slope transmission

(

dT

dV

)

was negative, the output, for a constant input, was periodic oscillations having a delay time larger the material response time. The nomenclature is explained in ref. 1.
Bistability in intracavity resonant degenerate 4-wave mixing in Na vapor
Authors: Lange W. , Köster E. , Mlynek J.
Published: February 2023

Resonant degenerate 4-wave mixing (DFWM) has proven to be a powerful technique to generate phase conjugate (PC) wave fronts. In this contribution we consider the situation where the nonlinear medium is placed inside a Fabry-Perot cavity (Fig. 1). In this geometry, the intracavity pump intensity and, as a consequence, also the PC emission are expected to exhibit bistable switching /1,2/. With respect to practical applications, intracavity PC might be of interest, e.g., for probing an optical memory element or for Q-switching a resonator with a phase conjugating mirror. Only recently, however, first experimental studies on bistability in intracavity PC have been performed /3,4/.
Poincarré Analysis of a Hybrid Bistable Device
Authors: Vallée Réal , Delisle Claude
Published: February 2023

We present experimental results obtained with an acoustooptic bistable device described by the differential-difference equation: where µ is the dynamical parameter, τd is the time delay and τ the response time. We will describe the time evolution of X(t) by constructing a 3-D phase space with the variables X(t), X(t-τd ) and X(t-2τd). The figure 1 shows a projection of the attractor of the system onto the plane defined by X(t-τd) and X(t) for τd / τ = 6 and µ = 1.05.
Multimode Instabilities of Homogeneously Broadened Lasers
Authors: Chakmakjian Stephen , Hillman Lloyd W. , Koch Karl , Stroud C.R.
Published: February 2023

Recent progress on experiments studying multimode instabilities in cw ring dye lasers is reviewed. The multimode instability that was first observed by Hillman etal.1 is shown to occur over a wide range of laser parameters. Parameters studied include pump power, cavity dispersion, and cavity lifetime2.
Optical Bistability with Surface Plasmons beyond Plane Waves in Nonlinear Dielectric
Authors: Agarwal G.S. , Dutta Gupta S.
Published: February 2023

Wysin et al1 suggested that the local field enhancement near a metal surface which occurs if surface plasmons are excited in a metal film, can be useful for observing optical bistability arising from the nonlinearity of the Kerr medium. Other geometrical arrangements2 have also been suggested. These studies assume plane waves in the nonlinear medium and use the Fresnel formulae for reflection and refraction from a layered medium but with linear refractive index replaced by the nonlinear refractive index. This assumes that the fields in the medium are homogeneous. However if surface plasmons are excited, then the fields are inhomogeneous and one has the problem of reflection and refraction from an inhomogeneous layered medium. The inhomogeneity is to be determined self consistently. Thus a proper treatment of optical bistability with surface plasmons should use the nonlinear solutions of the wave equation in Kerr medium. This is what we do in this paper.
Frequency-pushing Hysteresis of Single-mode, Standing-wave Gas Lasers Containing a Saturable Absorber
Authors: Englund John C.
Published: February 2023

I have shown previously that the on-resonance steady states of tuned, single-mode, standing-wave gas lasers can be destabilized by frequency perturbations1 rather than amplitude perturbations2, and that the threshold of such instability coincides with a bifurcation to branches of frequency-pushed steady states. Above such thresholds, both intensity1 and frequency3 hysteresis, as functions of the cavity detuning, are expected.
Stability of a 2-photon bistable system in a standing wave cavity
Authors: Maize S. , Thompson B.V. , Hassan S.S.
Published: February 2023

In the one photon OB problem, McCalls method [1] gives an accurate solution for the stationary behaviour of the forward and backward field envelopes while the Fleck approach [2] has serious faults [3,4]. A linear stability analysis using truncation [5] predicts instabilities of self-pulsing type on the upper transmission branch for C > 60 (C is the cooperation parameter). We have repeated this investigation but using McCall’s method in order to test how useful the truncation method is for time dependent problems. We find that the upper branch is now stable for several values of C > 60.
Bistability in Nonlinear Optical Waveguides
Authors: Bertolotti M. , Sibilia C. , AnseImi I.
Published: February 2023

The field distribution inside a nonlinear planar guiding structure is studied, in the case in which the refractive index of the nonlinear guide is given by with the following condition: being M2 and u3 the refractive index of the cladding and the substrate, respectively.
Analytical Solutions and Intrinsic Instabilities for the Polarization in Nonlinear Isotropic and Anisotropic Optical Media
Authors: Gregori G. , Wabnitz S.
Published: February 2023

Recently, exact solutions have been presented for the polarization evolution in an isotropic nonlinear medium with an externally induced birefringence [1-2], and the occurrence of instabilities and bifurcations has been predicted[2]. Otsuka and Yumoto[3] have also predicted self-induced instabilities in nonlinear anisotropic crystals of cubic symmetry, but no analytical solution was provided.
Bistability and Self-Pulsing Using Input Couplers on Nonlinear Planar Waveguides
Authors: Lukosz W. , Aklin B. , Briguet V. , Pirani P.
Published: February 2023

We report on experimental and theoretical work on input couplers on nonlinear planar waveguides. We found bistability, and self-pulsing for CW input powers. We observed the part

p
−

p
′

=

(

1
−

η
^

)

p

of the incident power p which is not coupled into the waveguide (

η
^

= coupling efficiency).
Longitudinal Effects in Increasing Absorption Optical Bistability
Authors: Olbright G. R. , Gibbs H. M. , Peyghambarian N. , Schmidt H. E. , Koch S. W. , Haug H.
Published: February 2023

Koch et al.1 have solved for the laser light intensity and the excitation density as a function of time and space (in the beam direction) in a semiconductor doped glass that exhibits increasing absorption2 optical bistability under pulsed operation. A kink in the excitation density that propagates as a discontinuity in the beam direction and manifests itself as a sawtooth variation in the output intensity is predicted. Gibbs et al.3 reported the first experimental observation of kinks in a sharp cut color filter. Kinks that are an emphatic illustration of the local nature of increasing absorption optical bistability are presented. Furthermore, kinks demonstrate an intrinsic dissimilarity between increasing absorption optical bistability and bistability dependent upon external feedback, where a longitudinal discontinuity cannot occur. If the input is an increasing ramp, then the front part of the sample reaches the condition, carrier density, and temperature, for switching down before the remainder, whose light intensity is reduced by absorption in the front. The discontinuity in the excitation density develops as a consequence of competition between transverse thermal conduction and heating of the sample by increasing absorption in the shielded back part of the sample. The number of discontinuities is limited by the pulse rise time, sample length, and conduction time, which scale as the square of the beam radius.
The Photorefractive Effect for Optical Processing
Authors: Glass A. M.
Published: February 2023

Since the discovery of the photorefractive effect in LiNbO3 two decades ago, considerable effort has been devoted to understanding and optimizing the phenomenon for a variety of applications. It is now recognized that this effect offers a very versatile nonlinear optical mechanism for parallel optical processing. The studies and application to date have made use of oxide materials such as LiNbO3, K (TaxNb1-x)O3, BaTiO3 and Bi12SiO20. Most of these materials exhibit relatively slow relaxation times which limits the manner in which optical processing can be performed. However, we have recently found that high mobility electro-optic semiconductors including InP, GaAs and CdTe offer attractive alternatives for photorefractive image processing: (a) Their recording sensitivities are comparable to oxide photorefractors (b) They offer near infrared responsivity in the spectral region of importance for semiconductor lasers (c) The high mobility allows fast photorefractive response ranging from subnanoseconds to milliseconds and (d) The optical and electrical properties are readily tailored by doping to suit specific applications. The basic mechanisms giving rise to the photorefractive effect in electro-optic semiconductors will be described and the sensitivity and speed limitations will be contrasted with those of ferroelectric crystals. Four wave mixing experiments demonstrating submicrosecond writing and erasure with microjoule pulses of infrared radiation will be reported. This corresponds to information processing at -1012bits/sec with energies of ~ 1 picojoule/bit for high contrast images. Considerably lower energies are required for reduced contrast and considerably faster response can be achieved with a degree of parallelism.
Effects of Holding-Field Noise on Optical Switching
Authors: Filipowicz P. , Garrison J. C. , Meystre P. , Wright E. M.
Published: February 2023

When trying to operate optically bistable systems as logical switches, one is confronted with the question of stability against noise in amplitude and frequency of the holding laser beam. It is generally accepted that this problem is governed by scaling laws which are, to a large extent, independent of the detailed description of the nonlinear medium. Therefore, we consider the case of a purely dispersive medium whose nonlinear susceptibility satisfies a Debye relaxation equation. The cavity is taken to be of moderate finesse and large bandwidth (short round-trip time).
Optical Bistability Experiments Using Samarium Vapour
Authors: Sandle W. J. , Parigger C.
Published: February 2023

Experimental investigations of optical bistability (OB) for systems with degenerate lower states have up to now relied principally on atomic sodium [1-4]. The study of the influence of lower level coherence effects in OB [5] is greatly aided by the use of a nonlinear medium having a transition with integral electronic angular momentum character. A suitable choice upon which we report here is the 4f6 6s2 (7F1) to 4f6 6s6p (7Foo) 570.68-nm transition in SmI, driven by linearly polarized laser excitation in a near-concentric Fabry-Perot cavity. Unlike the case of the Na J = 1/2 to J = 1/2 D1 transition, for which polarization asymmetry in switching (PS) develops spontaneously [1-4], for the above transition we find that the symmetry in the polarization is conserved. No polarization differences of σ+ with respect to σ− develop in the output from the optical cavity. This behaviour accords with the theoretical expectation [6] that PS is suppressed by transverse optical pumping.
Critical Behaviour and Optical Bistability of the Tavis-Cummings Model in a Driven Low-Q Cavity
Authors: Bullough R.K. , Hassan S.S. , Puri R.R.
Published: February 2023

The Tavis-Cummings model1 is one of the few exactly solvable quantum models in nonlinear optics: it consists of N > 1 2-level atoms interacting with a single mode of the quantised radiation field. The N atoms occupy a single site as in the Dicke model2; but there is no coupling to other modes of the field and no conventional radiation damping. Since the single mode is quantised in a cavity of finite volume this can be thought of as a physical cavity of infinite Q.
Nonlinear Guided Wave Phenomena
Authors: Seaton Colin T. , Stegeman George I.
Published: February 2023

Integrated optics waveguides are ideal media for nonlinear optical interactions because high power densities can be maintained over centimeter propagation distances. Recent work in our laboratory, as well as that of other workers in the field will be reviewed. Liquid crystal media placed on top of thin films provide simple nonlinear waveguides in which optical bistability, all-optical switching and the modulation of one light beam by a another have all been demonstrated for different materials and different polarization conditions. The optical tuning of surface gratings on InSb thin film waveguides will be described. Recent experiments on nonlinear coherent directional couplers will be reviewed. If time permits, new materials for nonlinear integrated optics waveguides will be discussed, as well as new developments in the theory of nonlinear guided waves.
Optical Waveguides in Multiple Quantum Well Structures
Authors: Sarid Dror , Gibbons Wayne M. , Warren Mial E.
Published: February 2023

Nonlinear channel waveguides can serve as building blocks for all-optical processing devices such as directional couplers, Mach-Zehnder interferometers, and ring channels. An attractive nonlinear medium for such devices is an excitonic system such as a MQW structure, since the nonlinearity is large and the operating wavelength is compatible with solid-state lasers. In contrast to electronic or bandfilling nonlinearities, the calculation of the parameters of an excitonic system is complicated by the fact that the absorption as well as the nonlinear refractive index are a function of the local intensity and the detuning frequency. We have used a theoretical model of a MQW structure which takes into account the broadening and the bleaching of the exciton resonance line. We find that the conventional figure of merit, n2/α, is inadequate to describe the required parameters for designing a nonlinear channel waveguide. Rather, one should calculate the total phase shift

Δ
Φ
=

∫
0

L

(

I
π

)

k

Δ
n
[
(
I
(
x
)
]
d
x

where Iπis 1/e of the incident intensity. Taking into acccount the Urbach tail as the background absorption, one obtains realistic parameters for constructing a nonlinear channel waveguide in GaAs MQW structures. We have also calculated the nonlinear response of submicrometer spheres of GaAs or MQW structures embedded in a linear dielectric. Applications of the pure and diluted excitonic systems for nonlinear channel waveguide devices will be discussed, and their relative merits compared.
Polarization Instability and Bistability in Birefringent Nonlinear Media
Authors: Winful Herbert G.
Published: February 2023

This paper presents a coupled mode theory of self-induced changes in the polarization state of an intense light beam in a birefringent nonlinear medium. The analysis is relevant to the operation of recently demonstrated all-optical logic gates, pulse shapers, and intensity discriminators that rely on intensity-dependent polarization states in birefringent optical fibers.1-3
Models for Absorption-induced Optical Bistability in CdS and Multiple Quantum Well GaAs
Authors: Haus J. W. , Sung C. C. , Li Y. C. , Bowden C. M. , Cook J. M.
Published: February 2023

Mirrorless optical bistability has been established in CdS1 and in multiple quantum well (MQW) GaAs structures2. The mechanism responsible for the bistable behavior in these semiconductors is the coupling between the temperature distribution and the electric field intensity in the sample. In these semiconductors, the mechanism is simple enough that a quantitative analysis should be possible. However, a successful model of bistability in these systems must await a careful experimental analysis of the thermal boundary conditions3. With this caveat we have proceeded with the theoretical development. Steady-state results for CdS and MQW GaAs are presented.
Generation of Squeezed States in Optical Bistability
Authors: Holm D. A. , Sargent M. , Capron B. A.
Published: February 2023

Over the past three years we have developed a quantum theory of multiwave mixing designed to determine effects of quantum noise on laser and optical bistability instabilities, pump/probe saturation spectroscopy, AM and FM modulation spectroscopy, and phase conjugation. The theory treats a classical pump field and one or two quantum-mechanical sidemode fields interacting with one- or two-photon, two-level media. The theory1 produces a master equation for the reduced sidemode density operator able to describe all of the above phenomena in a uniform way closely related to the corresponding semiclassical theories. It has led to a number of significant predictions about the effects of spontaneous emission on laser spectroscopy and optical instabilities.
Period Doubling and Intermittency in the Transmission of a Na Vapor Filled Fabry-Perot
Authors: Cecchi S. , Giusfredi G. , Salieri P. , Arecchi F.T.
Published: February 2023

The transmission of a coherent beam interacting with sodium atoms in a Fabry-Perot resonator displays a complex stationary and dynamical behaviour. It follows from the presence of many degrees of freedom, arising from the atomic structure and from the "velocity group" subdivision of the atoms in the inhomogeneously broadened interaction with the field.
Transverse Optical Bistability and Instabilities
Authors: Gibbs H. M. , Derstine M. W. , Tai K. , Valley J. F. , Le Berre M. , Ressayre E. , Tallet A.
Published: February 2023

A transverse optical bistability would not occur with a plane-wave input; it is characterized by pronounced changes in transverse profiles, but not in total transmission.1 The systems studied here consist of a single feedback mirror and a nonlinear medium (Na vapor) sufficiently thin that diffraction is negligible during the nonlinear radially dependent phase encoding. With the input focused beyond (before) the Na and the mirror center of curvature on the input (output) side of the Na, self-defocusing (self-focusing) optical bistability is seen--but only when the feedback is nonconcentric, i.e., the feedback beam is displaced off-axis relative to the input beam. If cylindrical lenses are used to form an elongated focus in the Na, bistability is still seen. This suggests that one-transverse-dimension (ID) theories may be adequate to describe the system's steady-state and transient behavior. ID numerical simulations with nonconcentric feedback are under way.
Nonlinear Optical Properties of Small Semiconductor Particles
Authors: Ricard D. , Hache F. , Roussignol P. , Flytzanis C.
Published: February 2023

Nonlinear optical phenomena such as optical phase conjugation or optical bistability could lead to a large variety of applications in the data processing field. However, the implementation of practical devices strongly depends upon the availability of appropriate nonlinear materials having, among other properties, a large value for x (3) and a fast response. With this respect, man-made composite materials such as the semiconductor-doped glasses hold great promise.
Two-Photon Optical Nonlinearities in Semiconductor Quantum Dots
Authors: Banyai L. , Lindberg M. , Koch S.W.
Published: February 2023

Third-order optical nonlinearities of semiconductor quantum dots are investigated theoretically. Two quantum confinement regimes are analyzed: i) the situation in which both, electrons and holes are quantum-confined and Coulomb interactions may be ignored; and ii) the regime where only the electrons are quantum-confined and the much heavier holes move in the Coulomb field of the average electron charge.
Biexcitonic Nonlinearity in GaAs/GaAIAs Quantum Wells and Wires
Authors: Banyai L. , Galbraith I. , Haug H.
Published: February 2023

Recent theoretical calculations predict a large biexcitonic binding energy in both GaAs/GaAIAs quantum well wires (QWWs)1 and quantum wells (QWs)2,3 and we examine whether this gives rise to a large, exploitable, nonlinearity around the biexciton resonance.
Modulational Polarization Instability in Birefringent Fibers
Authors: Trillo S. , Wabnitz S.
Published: February 2023

A wave propagating in a nonlinear dispersive medium may be unstable with respect to weak modulations.1 This modulational instability (MI) has been recently observed in optical fibers in the anomalous dispersion regime of propagation.2,3
Gain/Feedback Approach to Optical Instabilities in Sodium Vapor
Authors: Valley J. F. , Khitrova G. , Gibbs H. M.
Published: February 2023

We use the gain-feedback approach1 to explain a number of instabilities observed in sodium vapor with the laser frequency vL tuned to the defocusing side of line center at v0. The gain curve, which includes motion of the atoms, predicts two regions of possible gain: Rayleigh gain for frequencies v just above vL and Raman gain for v ≅vL - vR, where vR is the on-resonance Rabi frequency; see Fig. 1.2 Lasing based on these two gain mechanisms has been seen in three different feedback configurations. The new observations are: Rayleigh-gain lasing with no external mirrors using the distributed feedback of counterpropagating pump beams, Rayleigh-gain lasing without a foreign gas, Raman-gain lasing in a ring cavity (see Fig. 2), and both Rayleigh and Raman lasing using a single feedback mirror.
Non-Symmetrical Solitons in a Femtosecond Dye Laser
Authors: Salin F. , Grangier P. , Roger G. , Georges P. , Le Saux G. , Brun A.
Published: February 2023

We report here the first experimental observation of non-symmetrical N=2 solitons. These pulses are produced by a passively mode-locked and dispersion controlled dye laser. As we have previously shown [1] this type of laser can produce high-order soliton like pulses. These pulses are characterized by a modulated pulse train envelope with the N-l characteristic frequencies of a N-soliton.
The Squeezing Spectrum in Optical Bistability
Authors: Lugiato L.A. , Vadacchino M. , Castelli F.
Published: February 2023

We study the spectrum of squeezing in the light transmitted by a system of two-level atoms in an optical cavity driven by a coherent field, as recently observed by Kimble and collaborators. Our analysis does not introduce any restriction on the detuning parameters or on the relative order of magnitude of the atomic and cavity relaxation rates. Using the dressed-mode formalism, we derive explicit analytic expressions for the spectrum of squeezing and for the second-order intensity correlation function. We describe how the spectrum depends on the various parameters of the system; this study provides general indications on how to optimize the conditions to observe squeezing in optical bistability. A special attention is devoted to the changes of the spectrum under variation of the detuning parameters or on the ratio of cavity to atomic damping rate. In all cases, the changes are continuous and smooth, with quantitative variations in the level of squeezing. This indicates the existence of a single avenue to squeezing in this system. The bad-cavity direction is identified as especially convenient to obtain a significant amount of squeezing.
Optical Nonlinearities in Semiconductors
Authors: Koch S.W. , Haug H.
Published: February 2023

The theory of transient and steady state optical nonlinearities in semiconductors is discussed. A unifying description of the physical processes underlying the nonlinearities is given. The discussion is focussed on the spectral region around the fundamental absorption edge, and the analysis covers two distinctively different time domains.
Direct Measuremet of the Nonlinear Refractive Index Cross-Section for InSb at 10.6 µm Wavelength
Authors: Chua P.L. , Ji W. , Kar A.K. , Walker A.C.
Published: February 2023

Large refractive index changes observed in the InSb-10 µm system, due to the generation of free electron-hole pairs by a two-photon excitation mechanism, has previously been exploited to demonstrate a number of nonlinear effects (i.e. optical bistability, optical power limiting, etc.) [1-2]. Using a photo-Hall technique, we have directly measured for the first time the refractive index cross-section σ = Δn/ΔN (i.e. the refractive index change contribution per generated electron-hole pair) by monitoring the transmission of an InSb etalon, to determine the index change Δn while simultaneously observing the photo-Hall signal resulting from the photogenerated carrier desity ΔN.
Investigation of All-Epitaxial GaAs/GaAlAs Nonlinear Etalons
Authors: Kuszelewicz R. , Azoulay R. , Michel J.-C. , Brandon J. , Oudar J.-L.
Published: February 2023

In recent years, considerable interest has arisen for the realization of bistable devices with low (milliwatt) holding power, and optical gates with low (picojoule) switching energies. One of the most promising ways of obtaining such characteristics is to combine the use of excitonic or band gap resonnant semiconductor optical nonlinearities, with the implementation of small-size devices to achieve electronic and optical confinement (1). Nonlinear Fabry-Perot étalons with integrated mirrors are quite interesting in this respect because their inherent simplicity facilitates their miniaturization , as recently demonstrated (2).
Optical Switching in Glass Fibers: Experiments
Authors: Smith P. W.
Published: February 2023

There is at present a growing interest in developing photonic switching and signal-processing devices for future communications and computing applications. Because some optical devices can function in times shorter than those possible with electronics technology, it is tempting to suggest that photonic devices will be used in future signa1-processing systems to eliminate the current "electronics bottleneck".
Optical Computing Architectures and Logic Units
Authors: Wherrett B.S.
Published: February 2023

Nonlinear interference filters offer the prospect of 2-D arrays of all-optical memory and logic functions. In order to test the feasibility of these devices for information processing a sequence of optical arithmetic and logic units and associated circuit architectures have been designed. The 2-D schemes involve a parallel pipelined architecture with grid or shuffle interconnects between planes of processing elements. A sequence of bistable plates acts as a 2-D set of shift registers or time-delays, thus allowing synchronous operation of iterative circuits. Architectures for numeric processing (addition, multiplication, discrete Fourier transform), based on a single-pixel full-adder; and for cellular logic image processing (edge extraction, image expansion) are described. The experimental implementation of prototype circuits, to date of limited parallelism, is discussed. The design features required of the individual optically bistable and nonhysteretic nonlinear components are brought out and anticipated processing powers, based on the potential of various nonlinear etalon systems, are summarised.
Nonlinear Optical Effects at the Fundamental Absorption-Edge of Wide-Gap II-VI Semiconductors
Authors: Henneberger F.
Published: February 2023

Previous studies [1,2] have shown that very strong and fast optical nonlinearities occur near the fundamental absorption edge of the wide-gap II-VI semiconductors at room temperature. They are related to many-body effects (screening, gap-shrinkage, bandfilling) in the carrier-system excited and make these materials good candidates for optical signal processing applications in the visible spectral range.
Nonlinearity and Switching Behaviour of Thermooptical Schottky SEED Devices
Authors: Jäger D. , Forsmann F.
Published: February 2023

We present novel theoretical and experimental results on thermooptical SEED devices, using Si Schottky diodes (Fig. 1) illuminated by a Nd-YAG laser with λo = 1.06 µm. Low power bistability and multistability [1] are observed, where the nonlinearity is largely enhanced by the electrical heating [2]. It is shown that the external resistance which controls the electrical power, gives rise to an additional, externally induced nonlinearity. This leads to novel operation characteristics: Bistability with vanishing hysteresis widths but high contrast ratios, characteristics with tunable differential gain and a new kind of multistability with two interlacing hysteresis loops are obtained. Additionally, switching from high to low values of the dissipated powers is observed even with increasing optical input power. The resistance can significantly reduce the temperature range and so the necessary dissipated power. Finally, as the most important result, it is shown for the first time that the additional nonlinearity can be used to switch the device ON and OFF (Fig. 2) by using optical input signals and a constant holding power within the region of bistability. Also NAND operation is demonstrated.
Optical Bistability in Molecular Beam Deposited ZnSe/BaF2 Multilayer Interference Filters
Authors: Miller A , Staromlynska J , Muirhead I T , Lewis K L
Published: February 2023

Semiconductor interference filters based on II-VI semiconductors show promise as large area, room temperature, optically bistable devices for applications in digital optical circuits using visible light [11]. These active filters, operating by opto-thermally induced changes in material optical constants, have generally been fabricated by thermal evaporation of multilayers of ZnSe or ZnS and some low index material. Evaporated filters are limited in thickness and tend to suffer from drift of operating point during use. In this work we have studied Fabry-Perot filters deposited entirely in an ultra-high vacuum (UHV) system using molecular beam techniques (MBE). UHV/MBE fabrication produces a highly dense film structure, free of porosity and with low contamination levels which should improve the stability of these devices.
Transverse Optical Bistability in Gold Colloid Due to Self-Focusing
Authors: Liming Wang , Chunfei Li , Zhongxiao Zhang , Yan Jia
Published: February 2023

We demonstrated transverse optical bistability in a red gold colloid[1] experimentally for the first time. The threshold of optical bistability is 300 milliwatts and the switching time is 0.1 milliseconds. The optical bistability is due to the self-focusing effect in the red gold colloid. Figure 1 shows a strong self-focusing effect.
Theoretical Analysis of Transverse and Crosstalk Effects in Thermooptic Absorptive Bistability
Authors: Oberlé J. , Bigot J-Y. , Daunois A.
Published: February 2023

Fast switching times in thermooptic bistable elements held by a cw laser beam and driven by an external pulse have been observed [1,2,3]. An overheating of the nonlinear material may occur during the switching. In this case, a complicated switching behavior is observed [4]. This dynamics can be understood if the temporal variation of the medium temperature is calculated [5]. Moreover, in the experiments with CdS platelets, the transport of heat is very important and the complete spatio-temporal dynamics must be taken into account.
Spatial Chaos and Optical Memory
Authors: Firth W.J.
Published: February 2023

Optically bistable devices have an intrinsic two-state memory capability, but practical applications are likely to require the integration of large numbers of bistable elements into arrays of "pixels".[1] The packing density of such pixels will be limited by cross-talk, which may be e.g. thermal, diffusive or diffractive or indeed any combination.[2] The basic requirement of a binary memory is that it have stable states uniquely representing all possible combinations of binary digits. This paper shows how the existence and stability of such states can be established for the case of a linear array with diffusive coupling. Further, an explicit expression is obtained for the minium pixel separation at which full memory function obtains.
Internal Feedback Mechanisms of Optoelectronic Bistability in Cadmium Sulfide
Authors: Bogdanov S. V. , Lyssenko V. G.
Published: February 2023

Optical bistability caused by thermal heating is observed when the CdS crystal is excited near the I2 bound exciton absorption line [1]. Impact ionization of free and bound excitons occurs in the crystal upon its illumination in electric field. The probability of impact ionization depends in a threshold way on exciton and free carrier concentration. At a certain field dependent carrier concentratiοn avalanche occurs, the electric current therewith increases the crystal temperature by 5-20 K [2] which is followed by a red I2 shift. The shift leads to an increase in absorption, carrier density and current. Therefore, feedback results from impact ionization current heating the crystal (Fig. 1).
Delay Time in Optical Switching of Bistable Tandem Lasers
Authors: Öhlander Ulf , Sahlén Olof
Published: February 2023

A bistable laser (BLD), Ref.1, was switched with an optical set pulse (electrical reset) from a master laser (MLD), both InGaAsP buried-heterostructure 1.3 μm laser diodes, as shown in FIGURE 1.
Increasing Absorption Bistability in Hybrid Silicon Devices and the Control of the Characteristics
Authors: Zhai H. C. , Iyechika Y. , Jäger D.
Published: February 2023

Increasing absorption optical and optoelectronic bistability in hybrid thermooptical Si devices (Fig. 1) are studied at 1.06 μm both theoretically and experimentally. The optical nonlinearity of such SEED devices is largely enhanced by the optoelectronically generated electrical power [1,2] and it is shown that the characteristics can easily be controlled by the applied voltage. Additionally, it is found that the external resistance R adds a further nonlinearity. As an important result, two hysteresis cycles can now occur in succeeding regions of the input power (Fig. 2). If R is replaced by a conventional photodetector or a second SEED element, interesting logic operations between two independent optical signals are possible. Au doped samples reveal that the bistability depends on the orientation of the electric field. Since Au traps control also the absorption we conclude finally that the device characteristics can largely be engineered.
Steady State Operation of a Non-linear Fabry-Perot for Oblique Incidence : Polarization and Beam Angle Dependence
Authors: Thienpont H. , Danckaert J. , Veretennicoff I. , Jäger D. , Forsmann F.
Published: February 2023

The aim of the paper is to study the modification in the steady state behaviour of a bistable Fabry-Perot when the angle of incidence, the width and/or the polarization of the beam, impinging on the system is changed. It can be easily shown that, according to the ratio of beam width and spotsize, several regimes of operation should be distinguished. In the two-beam regime (large spotsize or small angle of incidence), Miller's approach (1) can be generalised, leading to strikingly different transmission and reflection characteristics of the device, according to polarization and angle of incidence (Fig. 1a, 2a). These differences originate mainly from the modulation of the feedback mechanism by the latter parameters.
Cascadable Restoring Digital Optical Logic and Optical Circuits using Bistable Elements: Prospects for Significant Processing Rates
Authors: Smith S.D.
Published: February 2023

From the starting point of mW-power infrared-driven digital optical logic elements working from nonlinearity of electronic origin, simple 2-element circuits were demonstrated with the capability of sub-microsecond cycle rates but with difficulties in fabrication of parallel arrays. Current work has therefore concentrated on devices made with thin-film coating techniques in which both conventional thermal evaporation and molecular beam deposited layers have been used. At comparable device diameter, operating powers are typically a few milliwatts, similar to the infrared electronic case. The early devices have shown sufficient stability to demonstrate 'hold and switch' circuits operating continuously so that the results of a processing operation can be stored. Gain of up to 10 has been typically observed but the available output signal limits subsequent switching speeds. Off-axis address ensures standard logic levels and thus a 3-element 'optical classical finite state machine' has been demonstrated to show restoring logic operation over many cycles as well as the necessary inversion function.
Overview of Optical Instabilities
Authors: Lugiato Luigi A.
Published: February 2023

The last decade witnessed a remarkable research activity, both theoretical and experimental, on the unstable phenomena which arise in optical systems. The development of the theory of optical bistability in the seventies played a major role in stimulating the interest in this subject. Most of this research concerned the onset of spontaneous oscillations and/or chaotic behaviour, and I will review some general theoretical results and few experiments that confirm them.
Phase and Frequency Dynamics in a Bidirectional Ring Laser
Authors: Abraham N.B. , Hoffer L.M. , Lippi G.L.
Published: February 2023

Homogeneously broadened bidirectional ring lasers show alternation of the lasing direction induced dynamically by a long-lived population grating and slight detuning of the laser cavity from the atomic resonance1. We show that the mode switching is accompanied by abrupt jumps by pi in the total relative phase of the system2. Our analysis reveals that the carrier frequencies of the two modes are not equal even though the two unidirectional steady state solutions have the same frequency2. When one mode dominates and the other is suppressed, the dominant mode has the steady state frequency. However, a mode growing in strength has a frequency closer to the atomic resonance while a mode falling in strength has a frequency further from the atomic resonance. The dynamically induced mode-pulling and mode-pushing can be as much as 25 % of the steady state frequency detuning. The shifting frequencies of the modes indicate that the standing wave interference pattern rotates in the laser ring cavity, alternately moving clockwise and counterclockwise with nearly equal and constant speeds. The longitudinal spatial hole-burning pattern consequently also rotates in the ring tending to wash out the population grating and keeping it from developing an amplitude of much more than one percent of the spatially averaged population inversion.
Beam Propagation Analysis of Modal Properties of Nonlinear Optical Waveguides
Authors: Jakubczyk Z. , Jerominek H. , Tremblay R. , Delisle C.
Published: February 2023

The beam-propagation method (BPM) is an accurate numerical procedure for describing the propagation of an arbitrary incoming optical field through a given optical system. The method can be based on either the full scalar-wave equation (Helmholtz equation) for the electric field, or on the Fresnel equation that is valid for paraxial field propagation. In this paper we adopt the more general, Helmholtz equation formalism. Although the numerical solution generated by BPM emphasizes the beam properties of the field, it contains implicitly all the information necessary for a complete description of the field in terms of modes. The Fourier transform of the field with respect to axial distance z at a single transverse point (x,y) yields the totality of all mode eigenvalues βn, including those that correspond to leaky or decaying modes. It is also possible to determine from a propagating-beam solution the weights of the modes. We have done it with the aid of a correlation function formed by multiplying the conjugate of the complex field amplitude at z = 0, and the complex field amplitude for arbitrary z and integrating over the waveguide cross section. The numerical Fourier transform with respect to z of the complex correlation function, applied in conjunction with digital-filtering techniques, has given us values for both the mode weights and eigenvalues. Furthermore, once the eigenvalues have been determined, the mode eigenfunctions could be computed by evaluating the Fourier transform of the field for β = βn.
Corrugated waveguides used as bistable components
Authors: Akhouayri H. , Neviere M. , Vincent P.
Published: February 2023

Bistable optical systems are of considerable interest to produce high-speed optical signal-processing devices. Among them, those that use a nonlinear optical medium are attractive because they allow the lowest possible switching time. By the use of a suitable electromagnetic resonance, the bistability threshold can be lowered to a reasonnable value, for the incident power. Keeping in mind that a bistable optical system should be well adapted to optical integration in a planar geometry, one is naturally confronted to a corrugated waveguide filled with a nonlinear (Kerr) medium.
Instabilities in the Power Spectrum of Mode-locked Semiconductor Lasers
Authors: Baums D. , Serenyi M. , Elsäßer W. , Göbel E.O.
Published: February 2023

We have performed systematic studies of the optical power spectrum of an actively mode-locked semiconductor laser as a function of the detuning between the modulation frequency and the inverse photon round trip time in the resonator.
Regenerative Oscillations and Dispersive-Absorptive Optical Hysteresises with Peculiar Regions in Semiconductor Interferometers
Authors: Grigor’yants A.V. , Rzhanov Yu.A. , Balkarei Yu.I. , Elinson M.I.
Published: February 2023

We consider semiconductor Fabry-Perot interferometer (FBI) where interband free carriers photogeneration and heating due to recombination make a different sign contribution to the refractive index and temperature shift of band edge results in induced absorption. Such situation is realized in a number of semiconductors which demonstrate optical bistability (OB). Using the parameters of InSb /1,2/ we have numerically investigated transformation of steady input-output characteristic IO(Iin) under variation of initial detuning δo of FPI. Different δo leads to the following characteristics: dispersive-absorptive hysteresis of "butterfly"-type /3/; "butterfly"-type hysteresis with unstable regions corresponding to McCall’s regenerative oscillations (RO) /4/; single-valued characteristic with region of RO; as well as characteristic containing region of RO and absorptive OB with sharp decreasing of output intensity IO at forward switching. The limits of changing of input intensity Iin, δo and characteristic thermal time are found, where RO and OB of dispersive and absorptive type are exist.
Interpretation of Intracavity Instabilities in Terms of Dynamic Stark Effect
Authors: Frey Robert , Thedrez Bruno
Published: February 2023

Periodic pulsations taking place in two-level filled high Q uni-directional ring cavities have been connected to the dynamic Stark effect occuring in the two-level system itself.