Transverse optical instability patterns in semiconductor microcavities: Polariton scattering and low-intensity all-optical switching

Abstract

We present a detailed theoretical study of transverse exciton-polariton patterns in semiconductor quantum well microcavities. These patterns are initiated by directional instabilities (driven mainly by polariton-polariton scattering) in the uniform pump-generated polariton field and are measured as optical patterns in a transverse plane in the far field. Based on a microscopic many-particle theory, we investigate the spatiotemporal dynamics of the formation, selection, and optical control of these patterns. An emphasis is placed on a previously proposed low-intensity, all-optical switching scheme designed to exploit these instability-driven patterns. Simulations and detailed analyses of simplified and more physically transparent models are used. Two aspects of the problem are studied in detail. First, we study the dependencies of the stability behaviors of various patterns, as well as transition time scales, on parameters relevant to the switching action. These parameters are the degree of built-in azimuthal anisotropy in the system and the switching (control) beam intensity. It is found that if the parameters are varied incrementally, the pattern system undergoes abrupt transitions at threshold parameter values, which are accompanied by multiple-stability and hysteresis behaviors. Moreover, during a real-time switching action, the transient dynamics of the system, in particular, the transition time scale, may depend significantly on the proximity of unstable patterns. The second aspect is a classification and detailed analysis of the polariton scattering processes contributing to the pattern dynamics, giving us an understanding of the selection and control of patterns as results of these processes' intricate interplay. The crucial role played by the (relative) phases of the polariton amplitudes in determining the gains and/or losses of polariton densities in various momentum modes is highlighted. As a result of this analysis, an interpretation of the actions of the various processes in terms of concepts commonly used in classical pattern-forming systems is given.

Spatial multistability induced by cross interactions of confined polariton modes

“…The states are scanned back in opposite order from the ground state to the fifth excited state when the power is decreased. The spatial profile of the beam is therefore determined by the lateral confinement of the optical modes; this mechanism differs from the one based on spontaneous pattern formation due to transverse instability in a resonantly pumped planar microcavity, which was recently proposed [41,42]. Although the ordering in energy is respected, not all of the states appear when we increase or decrease the excitation power.…”

All-optical flow control of a polariton condensate using nonresonant excitation

“…Equation (1) describes the dynamics of the coherent polariton field and is of the type of a modified GrossPitaevskii equation. The coherent part can be derived from a microscopic semiconductor theory in mean-field approximation and parabolic approximation for the lower polariton branch [27]; spin degrees of freedom [28] are not considered here. Equations (2) and (3) (1) with = 0.000 25 μm −2 mimics a relaxation term as it drives the polariton system to, on average, lower kinetic energies in spatial regions where interaction with the reservoir densities n A and n I occurs [31].…”

Pseudospin dynamics of exciton-polariton patterns in a coherently driven semiconductor microcavity

“…Along with other classical issues of nonlinear dynamics, recently the formation of periodic patterns was studied in polaritonic systems, too [17][18][19][20]. In Refs.…”

“…In Refs. [17][18][19] the pattern dynamics of spinless exciton-polaritons was investigated. Unlike those works, the influence of the exciton spin on the pattern dynamics is in the focus of the present contribution.…”