Y. C. Tse

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

(Received 26 February 2013; published 20 May 2013)We present a detailed theoretical study of transverse exciton-polariton patterns in semiconductor quantumwell microcavities. These patterns are initiated by directional instabilities (driven mainly by polariton-polaritonscattering) in the uniform pump-generated polariton field and are measured as optical patterns in a transverseplane in the far field. Based on a microscopic many-particle theory, we investigate the spatiotemporal dynamicsoftheformation,selection,andopticalcontrolofthesepatterns.Anemphasisisplacedonapreviouslyproposedlow-intensity, all-optical switching scheme designed to exploit these instability-driven patterns. Simulations anddetailed analyses of simplified and more physically transparent models are used. Two aspects of the problemare studied in detail. First, we study the dependencies of the stability behaviors of various patterns, as well astransition time scales, on parameters relevant to the switching action. These parameters are the degree of built-inazimuthal anisotropy in the system and the switching (control) beam intensity. It is found that if the parametersare varied incrementally, the pattern system undergoes abrupt transitions at threshold parameter values, whichare 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 theproximity of unstable patterns. The second aspect is a classification and detailed analysis of the polaritonscatteringprocessescontributingtothepatterndynamics,givingusanunderstandingoftheselectionandcontrolof patterns as results of these processes’ intricate interplay. The crucial role played by the (relative) phases of thepolariton amplitudes in determining the gains and/or losses of polariton densities in various momentum modesis highlighted. As a result of this analysis, an interpretation of the actions of the various processes in terms ofconcepts commonly used in classical pattern-forming systems is given.DOI: 10.1103/PhysRevB.87.205307 PACS number(s): 71

Patterns and switching dynamics in polaritonic quantum fluids in semiconductor microcavities [Invited]

The occurrence of instability-driven polariton density patterns in semiconductor quantum-well microcavities has been predicted and demonstrated experimentally. Simulations have shown that different patterns can become dominant under variations of excitation and structural conditions. We have devised and analyzed low-dimensional models to help understand the physics underlying these patterns’ competition. This paper reviews the results of these model studies, mainly on optical switching of the patterns. We also present results on how the control beam strength required for switching and the time scale of switching vary with physical parameters.

Control of Polariton Patterns in Semiconductor Microcavities

Polaritons in semiconductor microcavities can form patterns analogous to conventional Turing patterns, including two-spot and hexagon far field patterns. We present theoretical concepts of pattern formation and control, together with experimental observations.