Thermally induced optical bistability in PbTe at room temperature

Thermally induced optical bistability by continuous-wave CO₂ laser excitation is obtained for the first time in PbTe. Optical switching of the etalon atT=300K is achieved for input powers of tens of milliwatts. A theoretical analysis of the input-output characteristics is presented, where the temperature dependence of the free carrier absorption has been accounted for.     

Thermally induced optical bistability in a new polymeric blend at room temperature

The transition from the transmission to the reflection regime for an Ar⁺-laser beam propagating in the new polymeric blend PMMA-EVA at a nonlinear interface has been observed. A comparison between the experimental data and a calculation of the input optical intensity at which this transition should occur (1.45×10⁷ W m^–2) is presented using Kaplan's theory. The results suggest the presence of thermally induced optical bistability in PMMA-EVA.     

Optical bistability effects in a Tm,Ho:YLF laser at room temperature

We demonstrate strong optical bistability in a 2 microm continuous-wave Tm,Ho:YLF laser pumped by a 792 nm laser diode near room temperature. The bistable region is as much as 100 mW wide at 283 K and can be controlled by the temperature of the laser crystal. The influence of crystal temperature on the characteristics of optical bistability is obtained. The influence of the pump-to-mode ratio on the bistable characteristics of the laser is also discussed. To our knowledge this is the first report of optical bistability effects in Tm,Ho:YLF lasers.     

Optical bistability in a bidirectional ring cavity

We investigate the behaviour of a bistable absorber in a two-directional ring cavity. A hierarchy derived from the Maxwell and Bloch equations is used throughout without any truncation. In the stationary situation we recover the solution found by Bonifacio and Lugiato in the unidirectional ring cavity. Next, we consider the dynamics of the system when it is close to steady state. We find both the self-pulsing instability predicted by the afore-mentioned authors for the field propagating in the same direction of the injected signal, and a new instability originated by the counterpropagating field. Numerical results are given in the mean-field limit L1,T1.     

Optical bistability in a gaussian cavity mode

The mean field treatment of dispersive and absorptive bistability for two-level atoms in an optical cavity is extended to account for the gaussian envelope of the cavity mode. The principal modification to the plane wave cavity case is the raising of the critical threshold for absorptive bistability as compared to thresholds for dispersive bistability.     

Dispersive optical bistability in a ring cavity

Equations governing the behaviour of a single mode high-Q ring cavity are obtained for a coherent driving field (detuned to both cavity and atoms) and inhomogeneously broadened atomic transitions using a Hamiltonian approach. We find the region of bistability and critical points in the homogeneous broadening case. Numerical results including inhomogeneous broadening show that bistability is obtained more readily by detuning both the atomic transition and the cavity mode relative to the driving field.     

Dispersive optical bistability in a Fabry-Perot cavity

This is a numerical analysis of the steady-state Maxwell-Bloch equations in a Fabry-Perot cavity with standing waves, atomic detuning and cavity mistuning; the atoms are homogeneously broadened. In the Mean-Field Approximation (MFA) limit, the resulting output-input characteristics agree exactly with the analytical predictions for a ring cavity. This leads to the derivation of a state equation for the Fabry-Perot cavity in the MFA limit identical to that for a ring cavity. Agreement with the MFA within 4% are obtained when αL < 3, the mirror reflectivity is above 90%, and the cavity mistuning below 4% of its free spectral range. Simulations beyond the scope of the MFA are also made and the case of purely dispersive optical bistability is also considered.     

Optical bistability and multistability in a parametric region

We study the optical bistability (OB) and optical multistability (OM) behaviors in a five-level $\Lambda $ -type parametric region atomic system by two-photon resonant transitions. We find that the intensity threshold of OB and switching from OB to OM or vice versa can be controlled via quantum interference between different two-photon transitions pathways.     

Optical bistability based on the temperature dependence of the radiative recombination time: A new class of optical bistability components

The effect of the temperature dependence of the free-electron radiative recombination time on the onset of absorption optical bistability has been considered within the point-charge model. The existence of multistable states and the possibility of reducing by tens of times the switching temperatures and intensities and the differences between their corresponding values have been revealed. This permits one to reduce considerably the energy expended per switching event and, hence, to increase the speed of response of a bistable system.     

Stability conditions for two-photon optical bistability in a ring cavity

A stability analysis in the good-cavity and mean-field limits, of two-photon optical bistability arising when two beams at different frequencies interact with a nonlinear medium in a ring cavity, is presented. Another metastable state has been found to occur in the double-absorption case in certain circumstances, and the system may be described as exhibiting a form of tristability.     

Dissipative optical bistability in a Fabry–Perot cavity

From an interferometric point of view the bistable behavior due to a nonlinear absorptive material inside a Fabry–Perot cavity is studied. The effect of building standing wave and nonstanding wave on the bistable phenomena is discussed.     

Dispersive optical bistability in a nonideal Fabry-Pérot cavity

A stability analysis is performed for optical bistability in a Fabry-Pérot cavity with mirrors of arbitrary transmission coefficient. The mixed absorptive and dispersive régime is covered. In order to describe the system we use the Maxwell0Bloch equations formulated in terms of slowly varying envelopes. Standing-wave effects are completely taken into account by refraining from a truncation of the harmonic expansions for the polarization and the inversion density. We represent the solutions of the linearized Bloch hierarchy in terms of Chebyshev polynomials depending on the stationary electric field envelopes. In this way, we reduce the stability problem to a four-dimensional set of linear differential equations. Together with a couple of boundary conditions these equations govern the spatial behaviour of the deviations of the forward and the backward electric field envelopes. Our final stability problem becomes much simpler in the uniform-field limit and in the adiabatic limit. If we choose the stationary backward electric field equal to zero we recover results that were derived earlier for the case of a ring cavity.     

Optical properties of KCP at room temperature

A fit of the reflectivity data of KCP is given using the expressions of the small polaron theory. It is further shown that small polaron theory gives the same optical properties as either a two site model with a deformation coordinate and Franck Condon transitions between the sites or a Peierls subband model for nearly free electrons.     

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.     

Optical bistability through the cavity effect in a four-level open atomic medium

The optical bistability and multistability behavior in a ring cavity for the four-level open atomic system, driven by two coupling fields has been analyzed. It is shown that the presence of exit rate from cavity is having a dominant effect on generating the optical bi(multi) stability on the system. It is found that the effects of the injection rates can be used to control the threshold intensity. It is also found that optical bistability can convert to optical multistability or vice versa via the effect of intensity and detuning of the coupling fields.     

Effects of inhomogeneous broadening on optical bistability in a fabry-perot cavity

Dispersive optical bistability in a Fabry-Perot cavity is studied when the atomic transitions are inhomogeneously (Doppler and lorentzian) broadened. Exact numerical results are presented for both the steady state and the transient regimes. In the former case and for Doppler broadening, the atomic inversion shows “two-hole burning” into its velocity distribution. As the Doppler width increases, the bistability parameter has to be increased too in order to regain bistability as found in the ring cavity model. In the lorentzian case the bistable region tends to obliterate more markedly compared with the Doppler counterpart. In the transient regime, it is possible to generate thermal pulses by changing the temperature-dependent Doppler width harmonically with time. Hysteresis cycles are also generated with gaussian pulses. Multiple-valued behaviour of the transmitted light is exhibited in the Fabry-Perot cavity with inclusion of Doppler broadening.     

Controllable optical bistability of Bose-Einstein condensate in an optical cavity with a Kerr medium

We study the optical bistability for a Bose-Einstein condensate of atoms in a driven optical cavity with a Kerr medium. We find that both the threshold point of optical bistability transition and the width of optical bistability hysteresis can be controlled by appropriately adjusting the Kerr interaction between the photons. In particular, we show that the optical bistability will disappear when the Kerr interaction exceeds a critical value.     

Double-beam two-photon optical bistability in a Fabry-Perot cavity with polar molecules

Optical bistability in a micrometre-sized Fabry-Perot cavity, filled with appropriate polar molecules, is analysed after two incident beams (with frequenciesgw ₁ andgw ₂) produce in the system a two-photon resonance at frequencygw ₁ +gw ₂. One-photon resonances at the frequenciesgw ₁ andgw ₂ are discarded. It was not necessary to assume a particular relationship betweengw ₁ andgw ₂, and the single-beam two-photon optical bistability whengw ₁ andgw ₂ are of the same order or equal is emphasized.     

Dissipative optical solitons in the absence of bistability and modulation instability

Transversely one-dimensional localized field structures in a wide-aperture interferometer with inertialess nonlinearity of a threshold form are analyzed theoretically for the case when modulation instability of the transversely homogeneous field distributions is absent. It is shown that dissipative solitons exist even in the case of monostability (in the absence of bistability of the homogeneous distributions). In this case, the number of types of solitons turns out to be finite. The possibility of existence of pulsating solitons in an interferometer with inertialess nonlinearity is indicated.