Berlin 2001 – scientific programme

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Q: Quantenoptik

Q 16: Nonlinear Optics II

Q 16.3: Talk

Tuesday, April 3, 2001, 18:00–18:15, H 2013

Multiple pattern stability and noise-induced pattern transitions in a feedback system with photorefractive nonlinearity — •Philip Jander, Michael Schwab, and Cornelia Denz — Institut für Angewandte Physik, Technische Universität Darmstadt, Hochschulstr. 6, D-64289 Darmstadt, Germany

Photorefractive single feedback systems are known to produce a variety of different spatial patterns, among them hexagons, rolls, squares, rectangles or squeezed hexagons [1]. A multiple pattern region could be identified in experiment where different patterns were found for the same parameter values. Due to diffraction length variations effecting the feedback phase, these different patterns may alternate in time in a nonsystematic manner. We present detailed analysis of the probability for a specific pattern to appear in the multiple pattern region, depending on the photorefractive coupling strength, the mirror position and the transverse size of a circular Fourier filter in the feedback arm. We identified regions of bistability in our pattern forming feedback system and investigate the possibility to induce pattern transitions and transitions from homogeneous to patterned states by externally applied noise. Noise induced transitions in bistable systems constitute ideal candidates for the method of stochastic resonance. The prospects for an application of this method to our two-dimensional pattern forming system are discussed and an experimental realization is presented.

[1] M. Schwab, C. Denz, M. Saffman, Appl. Phys. B 69, 429–433 (1999)