Transition from spatio-temporal order to disorder in a single-feedback experiment

In a single-feedback setup with a Liquid Crystal Light Valve as optical non linearity, the formation of stationary hexagonal patterns can be observed. Under increase of pump power, the order of these regular patterns breaks do wn and a complex dynamics sets in. This transition is investigated for expe rimentally observed patterns in the self-focusing case with help of differe nt tools, namely time-average patterns, symmetry autocorrelation functions and temporal correlation functions. All methods indicate the existence of a second pump threshold, where order and dynamical properties of the pattern s change. (C) 1999 Elsevier Science Ltd. All rights reserved.