Pattern control by pump beam detuning in a photorefractive single feedback system

Abstract

Photorefractive single feedback systems are known to exhibit a variety of transverse patterns [1]. In addition to predominant hexagonal patterns, stripes, squares and squeezed hexagons can be observed to coexist and compete, providing bistable parameter regions. Such co bistabilities offer the chance to directly investigate . techniques to control the pattern formation process. Ce Detuning of the counterpropagating pump beams is C known to change the linear stability [2] and can be aX employed to control the relative stability of patterns in a parameter range where a bistability between different patterns exists.-3 -2 -1 0 1 2 3We experimentally demonstrate deterministic switching between square and squeezed hexagonal patterns by pump beam detuning and investigate its suitability as a control Intensity of addressed pattern type method.(here: a squeezed hexagonal pattern) vs. control signal strength.We present an analysis of the effect of pump detuning on fundamental unstable modes under one transverse dimension and discuss its relevance for the control of twodimensional patterns. Experimental results are compared to predictions obtained by means of a linear stability analysis.