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Photonic crystals are prime candidates for photonic integrated circuit applications, for instance in the field of optical telecommunications and optical computing. In this thesis we experimentally investigate the optical nonlinear behavior of single and coupled nanoresonators on a waveguide in a photonic crystal membrane. Photonic crystal resonators typically have small mode volume and high quality factor, which optimizes the optical nonlinearity crucial for active photonic devices. Our photonic crystal is designed for near-infrared light (~1550nm). Thermo-optical nonlinearity is the dominating nonlinearity in these InGaP photonic crystal waveguides. We measure the thermo-optical timescale in the system and find that the decay time of a mode is related to its mode profile. Additionally, we present a nonlinear mode mapping technique to measure the mode profile. We use an out-of-plane blue pump beam to spatially scan the surface of the photonic crystal and probe the mode. The pump light is absorbed and serves as a local heat source. Nonlinear effects, caused by free carrier absorption of infrared input light, significantly improve the resolution with respect to linear mode map techniques. This provides a non-invasive far-field imaging technique. Lastly, we look at two coupled nanocavities that give rise to optical multistability in the nonlinear regime. We investigate the phase space of the system by exciting the system with a puls of the out-of-plane pump beam. It turns out the pump pulse triggers a state change that remains stable after the pump is turned off. In this way we, find different energy branches of the multistable system, where the position of the pump pulse determines the thermo-optical state the system stabilizes in. Using this effect we demonstrate a programmable multistable all-optical switch, where we walk through the multistable phase space of the system, addressing several thermo-optical stable states in the system by lowering or raising the intern

Recent developments in nanofabrication have opened opportunities for strong light-matter interactions that can enhance optical nonlinearities, both classical and non-classical, for applications such as optical computing, quantum communication, and quantum computing. However, the challenge lies in integrating these optical nonlinearities efficiently and practically with fiber-based and silicon-based photonic circuits on a large scale and at low power. In this thesis, we aimed to achieve this integration of classical and quantum optical nonlinearities with fiber-based and silicon-based photonic circuits.For classical optical applications, optical bistability is a well-researched nonlinear optical phenomenon that has hysteresis in the output light intensity, resulting from two stable electromagnetic states. This can be utilized in various applications such as optical switches, memories, and differential amplifiers. However, integrating these applications on a large scale requires low-power optical nonlinearity, fast modulation speeds, and photonic designs with small footprints that are compatible with fiber optics or silicon photonic circuits. Thermo-optic devices are an effective means of producing optical bistability through thermally induced refractive index changes caused by optical absorption. The materials used must have high absorption coefficients and strong thermo-optic effects to realize low-power optical bistability. For this purpose, we choose high-density semiconductor quantum dots as the material platform and engineer nanobeam photonic crystal structures that can efficiently be coupled to an optical fiber while achieving low-power thermo-optical bistability. For applications that require non-classical nonlinearities such as quantum communication and quantum computing, single photons are promising carriers of quantum information due to their ability to propagate over long distances in optical fibers with extremely low loss. However, the efficient coupling

The optical Stark effect is a tell-tale signature of coherent light-matter interaction in excitonic systems, wherein an irradiating light beam tunes exciton transition frequencies. Here we show that, when excitons are placed in a nanophotonic cavity, the excitonic Stark effect can become highly nonlinear, exhibiting multivalued and hysteretic Stark shifts that depend on the history of the irradiating light. This multistable Stark effect (MSE) arises from feedback between the cavity mode occupation and excitonic population mediated by the Stark-induced mutual tuning of the cavity and excitonic resonances. Strikingly, the MSE manifests even for very dilute exciton concentrations and can yield discontinuous Stark shift jumps of order meV. We expect that the MSE can be realized in readily available transition metal dichalcogenide excitonic systems placed in planar photonic cavities at modest pump intensities. This phenomenon can provide new means to engineer coupled states of light and matter that can persist even in the single exciton limit.

The optical Stark effect is a tell-tale signature of coherent light-matter interaction in excitonic systems, wherein an irradiating light beam tunes exciton transition frequencies. Here we show that, when excitons are placed in a nanophotonic cavity, the excitonic Stark effect can become highly nonlinear, exhibiting multivalued and hysteretic Stark shifts that depend on the history of the irradiating light. This multistable Stark effect (MSE) arises from feedback between the cavity mode occupation and excitonic population mediated by the Stark-induced mutual tuning of the cavity and excitonic resonances. Strikingly, the MSE manifests even for very dilute exciton concentrations and can yield discontinuous Stark shift jumps of order meV. We expect that the MSE can be realized in readily available transition metal dichalcogenide excitonic systems placed in planar photonic cavities at modest pump intensities. This phenomenon can provide new means to engineer coupled states of light and matter that can persist even in the single exciton limit.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing., We study the optical response of a coupled asymmetric semiconductor quantum dot-spherical metal nanoparticle structure. The asymmetric quantum dot has permanent electric dipole moments that also interact with light. We derive the density matrix equations for the system including the modification of the electric field and the exciton-plasmon coupling. We emphasize on the effects of the nonlinear optical rectification and controlled optical bistability and analyze these phenomena for different values of the light intensity and different distances between the quantum dot and the metal nanoparticle. We show that when the system is set in a situation where optical bistability can be produced, the optical rectification of the hybrid system is bivalued. We also analyze the slow-down to reach the steady state when the system is driven close and far from the turning points., Ministerio de Ciencia e Innovación (MICINN), Universidad Complutense de Madrid/Banco de Santander, Sección Deptal. de Óptica (Óptica), Fac. de Óptica y Optometría, TRUE, pub

Injection locking is a nonlinear phenomenon in which two (or more) selfsustained oscillators can synchronize their oscillations, i.e., their operating frequencies and phases, provided that there exists some kind of coupling between them. This phenomenon can be observed in diverse disciplines such as mechanics, physics, engineering, even biology, psychology, etc. With development of electronics, injection locking has been used in a number of engineering applications comprising oscillators such as electrical or microwave, while recent breakthroughs in photonics paved the way for injection locking to be employed in optical systems such as lasers. Semiconductor lasers represent a kind of electrically driven self-sustained oscillators, which support electromagnetic oscillations inside the resonator cavity. By using various feedback mechanisms, the number of supported oscillations or modes can be controlled, providing single- or multi-mode operation of the laser. One of the sophisticated methods to control oscillations in one laser indeed relies on synchronization with another laser, i.e., on the technique of injection locking. In the case of injection-locked lasers, light from one, which is referred as “master” laser, is injected into the cavity of another (“slave”) laser, to provide for the coupling of the two oscillators. Under certain conditions, the slave laser can become stably locked to the frequency of the master one. In this technique, successful synchronization, i.e., stable locking of the two lasers, depends on injection parameters, which are the number of injected photons, (injection power), and the frequency detuning between the free-running frequencies of the master and slave lasers. The technique of injection locking has been proven to benefit laser dynamics, by increasing side-mode-suppression-ratio, thus providing single-mode operation, damping the relaxation oscillations, increasing the modulation bandwidth, reducing the linewidth and frequency chirping, Injekciona sinhronizacija je nelinearni fiziˇcki fenomen u kome dva (ili viˇse) oscilatora mogu da sinhroniziju svoje frekvencije i faze, ukoliko postoji odred¯ena sprega izmed¯u njih. Ovaj fizicˇki fenomen prisutan je u raznim sferama nauke, od mehanike, fizike i inˇzenjerstva, preko biologije, ˇcak i do psihologije, itd. Sa razvojem elektronike, injekciona sinhronizacija poˇcinje da nalazi svoje mesto u oscilatornim elektriˇcnim i mikrotalasnim sistemima, dok poslednja otkri´ca na polju fotonike pruˇzaju priliku da ova tehnika bude primenjena i u optiˇckim oscilatornim sistemima, poput lasera. Poluprovodniˇcki laseri su vrsta elektricˇno pobud¯enih oscilatora koji podrzˇavaju elektromagnetne oscilacije u laserskom rezonatoru. Postoje razni tipovi mehanizama na bazi povratne sprege koji se koriste za kontrolu podrˇzanih modova oscilacija, ˇcime je mogu´ce posti´ci monomodni ili multimodni rad lasera. Jedna od naprednijih tehnika se upravo bazira na efektu injekcione sinhronizacije sa drugim laserom, tj. svetlost iz jednog (vode´ceg) lasera se injektuje u rezonator drugog (pratec´eg) lasera, koji u slucˇaju da su ispunjeni odred¯eni uslovi, postaje stabilno sinhronizovan prema frekvenciji i fazi prate´ceg lasera. Uspeˇsnost injekcione sinhronizacije zavisi od parametra injekcije, na prvom mestu od koncentracije injektovanih fotona, tj. injektovane snage kao i od frekvencijske razdeˇsenosti dva lasera. Pokazano je da ova tehnika moˇze da doprinese poboljˇsanju dinamike lasera, tako ˇsto povec´ava potiskivanje nezˇeljenih modova i obezbed¯uje monomodni rezˇim rada, prigusˇuje relaksacione oscilacije u prelaznim reˇzimima prate´ceg lasera, pove´cava propusni opseg, smanjuje ˇsirinu linije i frekvencijski ˇcirp, itd. Zbog pomenutih prednosti, injekciono sinhronizovani laseri predloˇzeni su za primenu u modernim arhitekturama optiˇckih mreˇza, poput pasivnih optiˇckih mreˇza sa multipleksiranjem po talasnim duˇzinama, u kojima bi mogli da zamene daleko skuplje i sloˇzeni

We study polarization switching and hysteresis in a vertical-cavity surface-emitting laser (VCSEL) subject to an orthogonal optical injection, such that the polarization of the injected light is perpendicular to that of the free-running VCSEL. We use the framework of the spin-flip model to characterize the polarization state of the VCSEL as a function of the frequency detuning. With appropriated injection conditions, the orthogonal polarization turns on and locks to the injected field. Increasing and decreasing the detuning across the two locking boundaries results either in narrow or wide hysteresis cycles, or even in irreversible switching. These results are in a good agreement with recent experimental observations., Peer Reviewed, Postprint (published version)

We report experimental evidence of bistable phase locking in nonlinear optics, in particular, in a photorefractive oscillator emitting in few transverse modes. Bistable phase locking is a recently proposed method for converting a laserlike system, which is phase invariant, into a phase-bistable one by injecting a suitable spatially modulated monochromatic beam, resonant with the laser emission, into the optical cavity. We experimentally demonstrate that the emission on the fundamental TEM00 mode becomes phase bistable by injection of a beam with the shape of the TEM10 mode with appropriate frequency, in accordance with recent theoretical predictions [K. Staliunas et al., Phys. Rev. A 80, 025801 (2009)]. The experimental observations are supported by an analytical study of a few-transverse-mode photorefractive oscillator model., Postprint (published version)

The paper describes theoretical and experimental results that enabled the authors to proof optical bistability behavior of a specially modified bistable semiconductor laser diode (BLD) created on a structure with a saturable absorption section. A mathematical model of the light-current characteristic, condition for bistability and the basic parameters of the hysteresis loop were derived by solving a system of three rate equations. That system was used for simulation of the light-current characteristic and conditions of bistability of the realized BLDs. For selected operating points of the simulated light-current characteristic the parameters of hysteresis loop and element values of the BLD electrical equivalent circuit for small signal variations were calculated. The bistability was experimentally measured by the new time method devised for impulse bistability verification (IBV). The basic measured and calculated parameters of the hysteresis loop of the BLD light-current characteristic were compared.

Porous silicon (PSi) has been shown to be a material with varieties of nonlinear optical properties. These properties have been discussed in terms of its nature of photoluminescence mechanism such as quantum confinement, surface states and the role of impurities. PSi has also been shown to be a useful material for optical devices, and have potential applications in fields such as bio-sensing and efficient lighting. In the following thesis, I present my theoretical and experimental results in studying a nonlinear optical property, known as optical bistability, in mesoporous silicon microcavity devices.The results show significant optical hysteresis in the transmission and reflection properties of mesoporous silicon microcavities when illuminated with a 150 nanosecond pulsed laser at 532 nm. The optical hysteresis is shown to be transient in nature and the properties are strongly dependent on the porosity of the cavity layer. The onset and damage threshold intensity are also shown to be porosity dependent. Modeling suggests that the observed effects are due to changes in the nonlinear refractive index and the transient lifetime increases with increasing porosity. The role of surface states was also investigated on influencing the bistable process by passivating the internal porous surface with hydrosilylation chemistry.The role of the number of periods in the cavity structure is also studied. The cavity is doped with quantum dot to improve its switching intensity. The optical bistable property of the cavity was also investigated by using a 532 nm continuous wave (CW) laser with maximum power of 10 mW, modulated by an optical chopper. The only sample that yields significant hysteresis is the sample doped with quantum dot, with millisecond respone time. The results show that the sample doped with quantum dot shows both electronic and thermal process in forming optical hysteresis.Finally, I develop a theoretical model to study the transient hysteresis shape. The model su

The paper describes theoretical and experimental results that enabled the authors to proof optical bistability behavior of a specially modified bistable semiconductor laser diode (BLD) created on a structure with a saturable absorption section. A mathematical model of the light-current characteristic, condition for bistability and the basic parameters of the hysteresis loop were derived by solving a system of three rate equations. That system was used for simulation of the light-current characteristic and conditions of bistability of the realized BLDs. For selected operating points of the simulated light-current characteristic the parameters of hysteresis loop and element values of the BLD electrical equivalent circuit for small signal variations were calculated. The bistability was experimentally measured by the new time method devised for impulse bistability verification (IBV). The basic measured and calculated parameters of the hysteresis loop of the BLD light-current characteristic were compared.

The paper describes theoretical and experimental results that enabled the authors to proof optical bistability behavior of a specially modified bistable semiconductor laser diode (BLD) created on a structure with a saturable absorption section. A mathematical model of the light-current characteristic, condition for bistability and the basic parameters of the hysteresis loop were derived by solving a system of three rate equations. That system was used for simulation of the light-current characteristic and conditions of bistability of the realized BLDs. For selected operating points of the simulated light-current characteristic the parameters of hysteresis loop and element values of the BLD electrical equivalent circuit for small signal variations were calculated. The bistability was experimentally measured by the new time method devised for impulse bistability verification (IBV). The basic measured and calculated parameters of the hysteresis loop of the BLD light-current characteristic were compared.

The paper describes theoretical and experimental results that enabled the authors to proof optical bistability behavior of a specially modified bistable semiconductor laser diode (BLD) created on a structure with a saturable absorption section. A mathematical model of the light-current characteristic, condition for bistability and the basic parameters of the hysteresis loop were derived by solving a system of three rate equations. That system was used for simulation of the light-current characteristic and conditions of bistability of the realized BLDs. For selected operating points of the simulated light-current characteristic the parameters of hysteresis loop and element values of the BLD electrical equivalent circuit for small signal variations were calculated. The bistability was experimentally measured by the new time method devised for impulse bistability verification (IBV). The basic measured and calculated parameters of the hysteresis loop of the BLD light-current characteristic were compared.

The paper describes theoretical and experimental results that enabled the authors to proof optical bistability behavior of a specially modified bistable semiconductor laser diode (BLD) created on a structure with a saturable absorption section. A mathematical model of the light-current characteristic, condition for bistability and the basic parameters of the hysteresis loop were derived by solving a system of three rate equations. That system was used for simulation of the light-current characteristic and conditions of bistability of the realized BLDs. For selected operating points of the simulated light-current characteristic the parameters of hysteresis loop and element values of the BLD electrical equivalent circuit for small signal variations were calculated. The bistability was experimentally measured by the new time method devised for impulse bistability verification (IBV). The basic measured and calculated parameters of the hysteresis loop of the BLD light-current characteristic were compared.

Summary: The synchronization of coupled semiconductor lasers with delay is investigated by numerical simulations of the nonlinear dynamic models complemented by a stability analysis of the linearized system. The equations used in the dissertation are based on the well known "Lang-Kobayashi" model modified to include unidirectional and bidirectional coupling. Stability diagrams are calculated and supplemented by numerically integrated time series. Synchronization is determined and quantified by computing the cross-correlation function. It is found that synchronized states are achievable for a wide range of coupling constants and delay times. These findings have implications for experiment and technological applications, notably in cryptography., by Michael S. London., Thesis (Ph.D.)--Florida Atlantic University, 2011., Includes bibliography., Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web.

In this paper, we experimentally demonstrate continuously tunable pulse propagation in SOI microring resonators with mutual mode coupling, which is induced by nanosized gratings along the ring sidewalls. In the presence of the mutual mode coupling, dispersion-induced group delay is investigated in single-waveguide and double-waveguide coupled single-ring resonators, respectively. In particular, pulse propagation in the drop channel of a double-waveguide coupled resonator is observed and exhibits continuously tunable delay and advancement features in the experiment. Delayed pulses are also obtained at the reflection port of a single-waveguide coupled resonator due to the existence of backward whispering gallery mode (WGM)., QC 20100525

We report double-notch-shaped microdisk resonators for silicon nonlinear-optic applications with direct in/out coupling via the microdisk notches. We measure optical bistability and resonance wavelength rcdshifts induced by the notch-coupled pump light. (C) 2008 Optical Society of America

We report double-notch-shaped microdisk resonators for silicon nonlinear-optic applications with direct in/out coupling via the microdisk notches. We measure optical bistability and resonance wavelength rcdshifts induced by the notch-coupled pump light. (C) 2008 Optical Society of America

We report double-notch-shaped microdisk resonators for silicon nonlinear-optic applications with direct in/out coupling via the microdisk notches. We measure optical bistability and resonance wavelength rcdshifts induced by the notch-coupled pump light. (C) 2008 Optical Society of America

The bistability in a thin-film cavity system including a layer with the quasi-resonant polarization is considered. Bistability in reflection frequency dependence and arising phase drift can be applicable for creation of chirping mirrors for laser pulses transformation.

The bistability in a thin-film cavity system including a layer with the quasi-resonant polarization is considered. Bistability in reflection frequency dependence and arising phase drift can be applicable for creation of chirping mirrors for laser pulses transformation.

In this paper we analyze in detail the secondary bifurcations of stationary hexagonal patterns in a prototype model of nonlinear optics. Hexagonal pattern solutions with all allowed wavenumbers are computed and their linear stability is studied by means of a Bloch analysis. Depending on the wavenumber of the selected pattern we predict and numerically observe phase instabilities, amplitude instabilities, both stationary and oscillatory, and oscillatory finite wavelength bifurcations. The results presented here illustrate a typical bifurcation scenario for patterns with different wavenumbers in self-focusing systems.

We theoretically investigate the polarization-resolved dynamics of two vertical-cavity surface-emitting semiconductor lasers that are mutually coupled through coherent optical injection. We find a sequence of bistable polarization switchings that can be induced by either changing the coupling strength or the optical propagation phase. The successive polarization switchings are correlated to the creation of new compound-cavity modes when these parameters are continuously varied. The switching dynamics and the role of asymetries are also discussed.

We demonstrate that electromagnetic waves can transmit with unit transmittance through a slab of negative-permittivity media sandwiched between two identical slabs with high permittivity, although each single slab is nearly opaque. This type of transparency is accompanied by high magnetic fields, and is robust against incidence angles. Microwave experiments, in excellent agreement with finite-difference-time-domain simulations, are performed to successfully realize this idea.

We demonstrate that electromagnetic waves can transmit with unit transmittance through a slab of negative-permittivity media sandwiched between two identical slabs with high permittivity, although each single slab is nearly opaque. This type of transparency is accompanied by high magnetic fields, and is robust against incidence angles. Microwave experiments, in excellent agreement with finite-difference-time-domain simulations, are performed to successfully realize this idea.

Contents Introduction; 1. Reduction of the Maxwell–Schrödinger equations; 2. Parameter swept across a steady bifurcation I; 3. Parameter swept across a steady bifurcation II; 4. Optical bistability: constant input; 5. Optical bistability: variable input; 6. Multimode optical bistability; 7. Free running multimode lasers; 8. Antiphase dynamics; 9. Laser stability; 10. Second harmonic generation; 11. Saturable absorbers; 12. Transverse effects in optical bistability., info:eu-repo/semantics/published

Contents Introduction; 1. Reduction of the Maxwell–Schrödinger equations; 2. Parameter swept across a steady bifurcation I; 3. Parameter swept across a steady bifurcation II; 4. Optical bistability: constant input; 5. Optical bistability: variable input; 6. Multimode optical bistability; 7. Free running multimode lasers; 8. Antiphase dynamics; 9. Laser stability; 10. Second harmonic generation; 11. Saturable absorbers; 12. Transverse effects in optical bistability., info:eu-repo/semantics/published

We demonstrate that electromagnetic waves can transmit with unit transmittance through a slab of negative-permittivity media sandwiched between two identical slabs with high permittivity, although each single slab is nearly opaque. This type of transparency is accompanied by high magnetic fields, and is robust against incidence angles. Microwave experiments, in excellent agreement with finite-difference-time-domain simulations, are performed to successfully realize this idea.

We study the polarization response of a vertical-cavity surface-emitting laser, driven simultaneously by noise and two (or more) weak periodic signals. In the bistable regime, we observe experimentally the occurrence of stochastic resonance at a frequency that is absent in the input driving signal. The presence of this so-called ghost resonance is confirmed theoretically.

Truly bistable twisted nematic liquid crystal display has been fabricated using photoalignment. This display can be switched between the -22.5degrees and 157.5degrees twist states by breaking the anchoring condition on one of the substrates. The application of a photoalignable polymer SDA-1 was able to achieve the weak anchoring energy necessary for switching. Both theoretical and experimental results show that this mode has excellent contrast ratio and wide viewing angles. (C) 2003 American Institute of Physics.

Truly bistable twisted nematic liquid crystal display has been fabricated using photoalignment. This display can be switched between the -22.5degrees and 157.5degrees twist states by breaking the anchoring condition on one of the substrates. The application of a photoalignable polymer SDA-1 was able to achieve the weak anchoring energy necessary for switching. Both theoretical and experimental results show that this mode has excellent contrast ratio and wide viewing angles. (C) 2003 American Institute of Physics.

Truly bistable twisted nematic liquid crystal display has been fabricated using photoalignment. This display can be switched between the -22.5degrees and 157.5degrees twist states by breaking the anchoring condition on one of the substrates. The application of a photoalignable polymer SDA-1 was able to achieve the weak anchoring energy necessary for switching. Both theoretical and experimental results show that this mode has excellent contrast ratio and wide viewing angles. (C) 2003 American Institute of Physics.

Theory and experiments of single-mode ridge waveguide GaAs-AlGaAs semiconductor ring lasers are presented. The lasers are found to operate bidirectionally up to twice the threshold, where unidirectional operation starts. Bidirectional operation reveals that just above threshold, the lasers operate in a regime where the two counterpropagating modes are continuous wave. As the injected current is increased, a new regime appears where the intensities of the two counterpropagating modes undergo alternate sinusoidal oscillations with frequency in the tens of megahertz range. The regime with alternate oscillations was previously observed in ring lasers of the gas and dye type, and it is here reported and investigated in semiconductor ring lasers. A theoretical model based on a mean field approach for the two counterpropagating modes is proposed to study the semiconductor ring laser dynamics. Numerical results are in agreement with the regime sequence experimentally observed when the injected current is increased (i.e., bidirectional continuous-wave, bidirectional with alternate oscillations, unidirectional). The boundaries of the different regimes are studied as a function of the relevant parameters, which turn out to be the pump current and the conservative and dissipative scattering coefficients, responsible for an explicit linear coupling between the two counterpropagating field modes. By a fitting procedure, we obtain good numerical agreement between experiment and theory, and also an estimation for the otherwise unknown scattering parameters.

The calculus of variations is applied to electromagnetic fields in a layered nonlinear structure supporting a guided wave. The system also includes a phase-conjugate mirror (PCM). By introducing a variational dimension and using a collection of plane waves as a trial function, we approximate the exact solution of the nonlinear Kerr-Maxwell equation. The formalism is new, and it involves the nonlinear interference of multiple plane waves. A simple analytical expression for the nonlinear field in the presence of the PCM is derived, and the fact that the scattered intensities may become bistable when the angle of incidence is varied is demonstrated. In particular, our theory predicts the angular bistability in the backscattering direction, where the effect of the guided waves is subtle. Our numerical results are also in good agreement with other theoretical approaches and with the experimental data., QC 20100525

We investigate a new scheme for driving reflective bistable cholesteric displays. It relies on fast switching from the planar to the focal conic state. We show that 1 ms per line scanning speed is possible using conventional passive matrix drivers. In addition, there is no optical delay in the switching process.

The brightness and contrast ratio of bistable twisted nematic displays are studied using the parameter space approach. By plotting the contrast ratio as a function of the twist angle and birefringence of the display, regions where the bistable twisted nematic display shows the best contrast ratio are clearly shown. We also studied the switching mechanisms of such displays.

The brightness and contrast ratio of bistable twisted nematic displays are studied using the parameter space approach. By plotting the contrast ratio as a function of the twist angle and birefringence of the display, regions where the bistable twisted nematic display shows the best contrast ratio are clearly shown. We also studied the switching mechanisms of such displays.

We investigate a new scheme for driving reflective bistable cholesteric displays. It relies on fast switching from the planar to the focal conic state. We show that 1 ms per line scanning speed is possible using conventional passive matrix drivers. In addition, there is no optical delay in the switching process.

Contents Introduction; 1. Reduction of the Maxwell–Schrödinger equations; 2. Parameter swept across a steady bifurcation I; 3. Parameter swept across a steady bifurcation II; 4. Optical bistability: constant input; 5. Optical bistability: variable input; 6. Multimode optical bistability; 7. Free running multimode lasers; 8. Antiphase dynamics; 9. Laser stability; 10. Second harmonic generation; 11. Saturable absorbers; 12. Transverse effects in optical bistability., info:eu-repo/semantics/published

Contents Introduction; 1. Reduction of the Maxwell–Schrödinger equations; 2. Parameter swept across a steady bifurcation I; 3. Parameter swept across a steady bifurcation II; 4. Optical bistability: constant input; 5. Optical bistability: variable input; 6. Multimode optical bistability; 7. Free running multimode lasers; 8. Antiphase dynamics; 9. Laser stability; 10. Second harmonic generation; 11. Saturable absorbers; 12. Transverse effects in optical bistability., info:eu-repo/semantics/published

We investigate a new scheme for driving reflective bistable cholesteric displays. It relies on fast switching from the planar to the focal conic state. We show that 1 ms per line scanning speed is possible using conventional passive matrix drivers. In addition, there is no optical delay in the switching process.

The brightness and contrast ratio of bistable twisted nematic displays are studied using the parameter space approach. By plotting the contrast ratio as a function of the twist angle and birefringence of the display, regions where the bistable twisted nematic display shows the best contrast ratio are clearly shown. We also studied the switching mechanisms of such displays.

A new kind of resonator based on a nonlinear directional coupler with feedback is presented. The steady states are found and the map of the system is iterated, showing the existence of bistability, period doubling and chaos. The dependence of the dynamic features is discussed in terms of the parameters of the two different schemes of feedback studied in this work. A new device based on one of these schemes of feedback suitable as a routing unit is proposed., Peer Reviewed

The three-waveguide nonlinear directional coupler switching characteristic is studied using the eigenmodes of the structure (i.e. supermodes). This model, which is more exact than the one used in previous works, has allowed to confirm the three waveguide configuration as an alternative to the two waveguide nonlinear coupler. Moreover, an analytical expression for the critical power at which the switching between the output branches occurs has been found., Peer Reviewed

The optical switching capabilities of Distributed Bragg Reflector (DBR) structures, including Vertical Cavity Surface Emitting Lasers (VCSELs) are examined. Reflectivity switching is demonstrated using both thermal and carrier generated effects to alter the DBR/VCSEL layers' refractive indices. Optical bistability is demonstrated at room temperature, under CW photopumped excitation. The optical bistability hysteresis is controllable by spectral location of the pump on the stop band edge. In the VCSEL, reflective bistability is also evidenced; additionally, this bistability is accompanied by a bistability in the VCSEL lasing output intensity, spot size, and wavelength. Modeling of the DBR/VCSEL thermally induced bistability was accomplished using an iterative, three dimensional Green's function solution to the laser induced heat equation. The model predicts thermally generated bistability, indicating a wavelength dependence, reflectivity jump, self focusing induced spot size change, and wavelength jump commensurate with the experimental data. Reflectivity switching due to carrier effects is also demonstrated, the DBR and VCSELs exhibiting subpicosecond switching speeds and contrast ratios of 3:1. Carrier heating, two photon absorption, and thermal components of the reflectivity switching capabilities are examined and found to be consistent with measured nonlinear response characteristics for the refractive index in AlGaAs.

Utilizing laser diode or light emitting diode hybrid bi-stable circuit composites, optical multistability and optical XOR logic gates as well as R-S flip-flops have been obtained. This type of optoelectronic logic circuitry and very large scale integrated (VLSI) technology are fully compatible. Because this is the case, it is hoped to apply it to optical information processing, optical signals, and optical computing. (AN), Trans. of Guangxue Xuebao (China) v9 n11 p983-988, Nov 89.

Trans. of Keji Ribao (China) n228 p9 1991.

In this work we analyze two different behaviors in a nonlinear passive fiber ring cavity with a synchronously pulsed pump iterating the infinite-dimensional Ikeda map. First, we show optical bistability with normal and anomalous dispersions. The obtained numerical results are compared with the cw pump case. Secondly, these cavities are subject to a temporal symmetry-breaking instability with anomalous dispersion. This instability is described and the range of parameters for its appearance is shown and discussed. © Taylor & Francis Group, LLC., SCOPUS: ar.j, info:eu-repo/semantics/published

In this work we analyze two different behaviors in a nonlinear passive fiber ring cavity with a synchronously pulsed pump iterating the infinite-dimensional Ikeda map. First, we show optical bistability with normal and anomalous dispersions. The obtained numerical results are compared with the cw pump case. Secondly, these cavities are subject to a temporal symmetry-breaking instability with anomalous dispersion. This instability is described and the range of parameters for its appearance is shown and discussed. © Taylor & Francis Group, LLC., SCOPUS: ar.j, info:eu-repo/semantics/published

Passive fiber cavities are basic nonlinear optical systems that are described by simple models - however they have a rich spectrum of complex behaviors (optical bistability, period-doubling bifurcations, chaos, modulational instability). From a practical point of view their study would have direct implications in the understanding of more complex cavity-based optical devices such as fiber lasers, Fabry-Perot lasers or APM lasers. Moreover, passive fiber cavities have potential applications in telecommunications as ultra-short pulse generators and as optical memories using their bistable behavior. This work is a contribution to the study of this bistable behavior with pulsed input, so that the device studied could be used for pulsed optical memory storage., Peer Reviewed, Postprint (published version)