The role of bistability in stochastic resonance

We consider stochastic resonance in a continuous cyclostationary one dimensional process. For an appropriate choice of the control parameters (e.g., as the result of an underlying higher dimensional dynamics) the stationary probability density of the process may grow bimodal even in the absence of an energetic barrier: this is no sufficient condition for stochastic resonance to occur.     

Optical bistability in semiconductor lasers

Optical and Quantum Electronics -     

Optical bistability in a three-level semiconductor quantum-well system

Optical bistable behavior in a unidirectional ring cavity (or a Fabry–Pérot cavity) containing a semiconductor quantum well, described as a three-level ladder-type system with similar transition energies, has been studied. The system interacts with a strong driving field which is in two-photon resonance with the intersubband transition and thus simultaneously drives all three levels into phase-locked quantum coherence. The threshold for switching to upper branch of the bistable curve is found to be reduced due to the presence of quantum interference. Such system can be used for making efficient and fast all-optical switching devices. PACS 78.67.De; 42.50.Hz; 78.20.Bh     

Hysteresis and memory of the magnetic resonance of conduction electrons in solids. From bistability to stochastic resonance

The magnetic resonance line of conduction electrons in solids may exhibit bistable hysteresis if several conditions are fulfilled. Its mechanism is presented and the manifestation of bistability in the ESR of conduction electrons in single crystal and polycrystalline samples is discussed. The characteristics of the dynamics of the bistability show that bistable resonance can be assimilated to one-dimensional overdamped motion of the spin system in the nuclear field space, driven by a bistable potential. It is shown for the first time that noise acting on this bistable resonance can create order, by the phenomenon of stochastic resonance.     

Absorptive and dispersive bistability in semiconductor injection lasers

Recent progress in the study of both absorptive and dispersive bistability in semiconductor injection lasers is reported. Inhomogeneously excited semiconductor lasers as an absorptive case, and laser diode optical amplifiers and optical injection locking systems of laser diodes as dispersive cases, are described. Applications of bistable semiconductor lasers, such as optical memories, optical regenerative amplifiers and all-optical switching, are also discussed.     

Phase-dependent optical bistability and multistability in a semiconductor quantum well system

We theoretically investigate the hybrid absorptive-dispersive optical bistability and multistability in a four-level inverted-Y quantum well system inside a unidirectional ring cavity. We find that the coupling field, the pumping field as well as the cycling field can affect the optical bistability and multistability dramatically, which can be used to manipulate efficiently the threshold intensity and the hysteresis loop. The effects of the relative phase and the electronic cooperation parameter on the OB and OM are also studied. Our study is much more practical than its atomic counterpart due to its flexible design and the wide adjustable parameters. Thus, it may provide some new possibilities for technological applications in optoelectronics and solid-state quantum information science.     

Frequency bistability of a semiconductor laser under a frequency-dependent feedback

The emission frequency of a diode laser submitted to a frequency-dependent optoelectronic feedback is observed to have more than one stable operation point together with a stable power emission. This is, to our knowledge, the first observation of bistability exclusively in the frequency of an optical system. The experiment was carried out with a semiconductor laser coupled to the cesium D2 line by an orthogonally polarized frequency-sensitive optical feedback.     

Current bistability in resonant tunneling through a semiconductor quantum dot

We discuss resonant tunneling through quantum dot energy levels considering the charging energy of the dot. The hamiltonian of the system is reduced to a form of the Anderson hamiltonian of resonant tunneling. The mean-field approximation is applied and current–voltage characteristics are evaluated. The self-consistent solution is investigated for the low tunneling rate case in the low-temperature condition. The current bistability and the related current hysteresis are pointed out. The Coulomb staircase is shown in the current–voltage characteristics. These features are all due to Coulomb repulsion within the dot.     

Optical bistability of a layered semiconductor in the exciton absorption region

The effect of specific features of the exciton and phonon spectra of layered semiconductors on the conditions of realization of optical bistability in the exciton absorption region has been theoretically investigated by the Green’s function method. By the example of the 2H polytype of PbI₂, it is shown that effective exciton scattering from low-energy bending-wave vibrations leads to a blue shift of the frequency range of bistability realization and its narrowing; expansion of the temperature range of bistability observation; and a shift of the hysteresis loop to higher intensities, accompanied by a decrease in its height and width. The possibility of observing polarization optical bistability, which is related to the dependence of the exciton energy spectrum on the propagation direction of a light wave in a crystal, is also substantiated.     

Ferromagnetic resonance and bistability field in a uniaxial magnetic film

Peculiarities of ferromagnetic resonance (FMR) corresponding to bias along the “hard” magnetic axis of a film with 2D uniaxial anisotropy are studied based on numerical solution of magnetic moment dynamics equations. It is shown that an additional resonance peak is formed in the FMR spectrum in the vicinity of “bistability field” H _b . The dependence of this field on the amplitude of the microwave field and damping parameters is analyzed.     

Magnetooptical bistability of a layered semiconductor in the region of exciton absorption

The effect of weak external magnetic fields on the conditions for implementing optical bistability in the region of exciton absorption of layered semiconductors has been theoretically investigated. By the example of the 2H polytype of lead diiodide, it is shown that, changing the strength of an external magnetic field, one can form conditions for implementing bistability and effectively control the position and sizes of the hysteresis loop of exciton absorption.     

Tunable all-optical bistability in a semiconductor quantum dot damped by a phase-dependent reservoir

We propose a method of frequency and phase control of optical bistability in a unidirectional ring cavity containing a semiconductor structure which is characterized as a ladder three-level system. The system interacts with a coherent probe field, and a control field which consists of a strong coherent field and a weak amplitude-fluctuating stochastic field. A perturbative solution of the master equation of the system allows to eliminate the stochastic field and provides a physical picture in terms of correlation properties of the stochastic field. We find that the bistable response can be modified strongly by means of the amplitude, the frequency and the phase of the stochastic field. In order to illustrate the feasibility of the results, we use parameter values corresponding to an semiconductor quantum dot (QD). This investigation may be used to optimize and control the optical switching process in the QD solid-state system, which is much more practical than that in atomic systems.     

Tunable asymmetrical Fano resonance and bistability in a microcavity-resonator-coupled Mach-Zehnder interferometer

We propose a simple microresonator scheme for a Mach-Zehnder interferometer in which a microresonator is side coupled to one arm and a phase shifter is introduced into the other arm, to produce an asymmetric Fano-resonance line shape. In this system, a phase shifter is used to control the variation of the asymmetric line shape, with another reverse resonance next to a resonance minimum over a very narrow frequency range, which results from the interference between a direct channel and a high-Q resonance indirect channel. We also theoretically investigate the novel bistability characteristic based on these shapes.     

Optical bistability in a triple semiconductor quantum well structure with tunnelling-induced interference

We study the behavior of optical bistability (OB) in a triple semiconductor quantum well structure with tunnelling-induced interference, where the system is driven coherently by the probe laser inside the unidirectional ring cavity. The results show that we are able to control efficiently the bistable threshold intensity and the hysteresis loop by tuning the parameters of the system such as laser frequency and tunnelling-induced frequency splitting. This investigation can be used for the development of new types of nanoelectronic devices for realizing switching process.