Absorption optical bistability in semiconductors under the action of an external electric field

The conditions for the realization of absorption optical bistability under the simultaneous action of two (radiative and nonradiative) mechanisms of recombination of free charge carriers are investigated. It is shown that, in the diffusion mechanism of stream of free electrons from the beam axis, the temperature dependence of radiative recombination does not expand the temperature range of the thermostat in which the optical bistability occurs. A scheme is proposed with application of an external transverse electric field, which makes it possible to realize absorption optical bistability at any ambient temperature. An important advantage of this scheme is the conservation of the state of a bistable system after the action of a light pulse and a significant decrease in the energy spent on cooling of the medium.     

Tunable double-beam optical bistability in an asymmetric double quantum-well system

We have proposed a scheme for double-beam optical bistability in a tunnel-coupled asymmetric double quantum-well driven by two optical fields circulating inside two independently unidirectional ring cavities. In contrast to the single-cavity case where single-photon saturated absorption and self Kerr-nonlinearity are dominant, the two-photon absorption and cross phase modulation can be enhanced via tunneling induced interference and have an important influence to the formation of bistability. The bistable behavior can be controlled effectively via the system parameters such as the input and detuning of control field, the detuning of the probe field, Fano interference strength and cooperation parameter. Furthermore, the proposed scheme has the ability to manipulate the outputs of two optical cavities simultaneously. Due to the flexible design of semiconductor quantum well, our scheme is more practical than atomic system, therefore it can be utilized to achieve dual all-optical switching which has application in optical communication and computing.     

Optical bistability induced by quantum coherence in a negative index atomic medium

Bistability behaviors in an optical ring cavity filled with a dense V-type four-level atomic medium are theoretically investigated. It is found that the optical bistability can appear in the negative refraction frequency band, while both the bistability and multi-stability can occur in the positive refraction frequency bands. Therefore, optical bistability can be realized from conventional material to negative index material due to quantum coherence in our scheme.     

Ultra-Low Threshold Optical Bistability and Multi-Stability in Dielecrtric Slab Doped with Semiconductor Quantum Well

A scheme for switching of the optical bistability (OB) and multi-stability (OM) in a dielectric slab doped with a three-level ladder-configuration n-doped semiconductor quantum well is simulated. It is shown that the bistable behavior of the system in dielectric slab can be controlled via amplitude or relative phase of applied fields. This optical system may provide some new possibilities for test the switching process.     

Optical bistability using quantum coherence in a microwave-driven four-level atomic system

The behavior of the optical bistability (OB) is investigated in an optical system which consists of a four-level atomic system with a microwave drive field and an optical cavity. It is found that the optical bistability can be accomplished by adjusting different physical parameters in both steady and transient process. Due to the existence of the microwave drive field, the optical bistability can be also obtained even under weak coherent coupling field condition. Since the intensity and phase of microwave drive field can be conveniently modulated, this optical system provides a new experimental method to test the optical bistability theory.     

非相干泵浦过程对光学双稳的影响

研究了低能级偶极子的非相干泵浦过程环形腔中双稳行为的影响，结果表明，耦合系统的双稳机制为非相干泵浦过程的干涉性，双稳迟滞环与非相干泵浦场有严格的对应关系，在一定条件下，甚至出现多稳态，可以利用非相干泵浦的干步性能控制光学双稳。     

Modified Bloch Equations for Subsystems of Two-Level Atoms

Modified Bloch equations that describe the interaction of high-power optical radiation with a dense resonance medium consisting of two subsystems of different two-level atoms of high density are obtained. It is shown that, unlike the one-component resonance medium in which the effect of internal optical bistability manifests itself on the red wing of the absorption line, in the two-component system it appears on the blue wing of one component of the system. The switching of the two subsystems from one steady state to another occurs at the same points of rotation of the hysteresis dependence of the population differences of resonance atomic levels on the radiation intensity that varies adiabatically slowly. The influence of the processes of upconversion on the spectral-threshold characteristics of the effect of internal optical bistability is investigated.     

Controllable optical bistability and multistability in a rare-earth-ion-doped optical fiber

We investigated the optical bistability and multistability in an Er³⁺-doped ZrF₄–BaF₂–LaF₃–AlF₃–NaF optical fiber inside an optical ring cavity. It is found that the optical bistability and multistability can be easily controlled via adjusting properly the parameters of the corresponding system. Our scheme may provide some new possibilities for technological applications in optoelectronics and optical-fiber communication.     

有三重态的四能级系统的光学双稳态

对一种有着单重态和三重态的典型的有机物的四能级系统的光学双稳进行了研究。由密度矩阵的速率方程近拟推导出了光学双稳的状态方程。对单重态和三重态吸收或色散情况下的双稳情况用数值解的方法进行了讨论。文中分析了单重态和三重态的合作参数、原子失谐参数和腔失谐参数对双稳的影响。     

Optical bistability due to virtual formation of biexcitons in semiconductors

Intrinsic optical bistability is theoretically investigated in a coherent photon-biexciton system. It is shown that bistability due to virtual two photon-biexciton transitions could occur if the system were pumped by a single external field. The conditions for the appearance of the bistability are determined.     

A study of optical properties of a four-level atomic system via vacuum-induced coherence effects

This paper studies the effects of vacuum-induced coherence(VIC) in a four-level atomic system.The effects of VIC lead to the coherent hole burnings exhibited in the system at some certain points of the Rabi frequency.This is also the reason for the enhancement of the coherent population trapping.In addition,optical bistability occurs in the evolution curves of absorption versus the phase of Rabi frequencies.     

FP腔中光驱动微悬臂的双稳效应的研究

研究了高灵敏度悬臂梁与光纤端面构筑的低精细度FP型光腔中光驱动的悬臂梁振动的双稳效应。通过改变输入到光腔内的激光功率,检测与之相应的悬臂梁的形变。在实验中发现悬臂梁的形变随激光功率的改变呈现非线性变化的关系,在激光功率增大到一定闽值时可以诱导产生光力双稳效应。通过改变光腔初始腔长成功实现了对产生光力双稳效应阈值的调节。     

Multiple bistability in an optical fibre double-ring resonator by using degenerate two-wave mixing

A theoretical study is presented of multiple bistability in a single-mode optical fibre double-ring resonator using an all-fibre scheme involving degenerate two-wave mixing. Two successive bistable hysteresis loops (one is a normal type and another an inverting type) are formed in the input-output transmission curve. The dependence of the multiple bistability on major parameters of the fibres and the couplers is investigated.     

Controlling the optical bistability via interacting dark-state resonances

We analyze the behavior of optical bistability in a four-level mercury atomic system driven by a cavity and two external coherent fields by means of a unidirectional ring cavity. We find that without interacting dark resonances and for large intensity of coupling field, the optical bistability disappears. So, the double dark resonances could significantly establish the optical bistability. Moreover, we demonstrate that the double dark resonances can dramatically reduce the threshold of optical bistability.     

Low-threshold bistable reflection assisted by oscillating wave interaction with Kerr nonlinear medium

Owing to the enormously enhanced oscillating wave, a minute variation of the incident light intensity will give rise to a change in the dielectric constant of the Kerr nonlinear medium and lead to a bistable reflection with an ultra-low threshold intensity, which is closely related to the angle of incidence and the thickness of the Kerr nonlinear medium. The criterion for the existence of optical bistability is derived. Our bistability scheme is simple and not limited to the TM-polarization.     

Thin CdS platelets — a model case for the study and optimization of thermally induced absorptive and dispersive optical bistability

Thermally induced optical bistability of thin CdS platelets is shown to be a highly suitable model case for the study of interactions between absorptive and dispersive switching mechanisms. Beyond previous studies concerning this type of bistability, systematic investigations were necessary to obtain a set of optimization criteria concerning a desired hysteresis feature. Despite the fact that thermally induced bistability of CdS may exhibit too long switching times for application in optoelectronics, it is a valuable system for the investigation of general features of bistable processes in a very detailed manner and for the development of reliable quantitative models. The appearance of different forms of thermally induced optical bistability in CdS is discussed in dependence of switching power, temperature, shallow-impurity concentration, and of system as well as of sample configuration.     

Pure Dispersive Optical Bistability of Four－level System in a Fabry－Perot Cavity

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Optical bistability and multi-stability in a four-level atomic scheme

We investigate the optical bistability (OB) and optical multi-stability (OM) in a four-level Y-type atomic system. It is found that the optical bistability can strongly be affected by intensity and frequency detuning of coupling and probe fields. The effect of spontaneously generated coherence on phase control of the OB and OM is then discussed. It has also been shown that the optical bistability can be switched to optical multi-stability just by the quantum interference mechanism and relative phase of applied fields.     

Optical bistability via quantum interference from incoherent pumping and spontaneous emission

We theoretically investigate the optical bistability (OB) in a V-type three-level atomic system confined in a unidirectional ring cavity via incoherent pumping field. It is shown that the threshold of optical bistability can be controlled by the rate of an incoherent pumping field and by interference mechanism arising from the spontaneous emission and incoherent pumping field. We demonstrate that the optical bistability converts to optical multi-stability (OM) by the quantum interference mechanism.     

Dynamical coupling between a Bose–Einstein condensate and a cavity optical lattice

A Bose–Einstein condensate is dispersively coupled to a single mode of an ultra-high finesse optical cavity. The system is governed by strong interactions between the atomic motion and the light field even at the level of single quanta. While coherently pumping the cavity mode the condensate is subject to the cavity optical lattice potential whose depth depends nonlinearly on the atomic density distribution. We observe optical bistability already below the single photon level and strong back-action dynamics which tunes the coupled system periodically out of resonance.