OPTICAL DISSIPATIVE STRUCTURES WITH A CON TROLLED SPATIAL PERIOD IN ANONLINEAR-SYSTEM AND A FOURIER FILTER IN A FEEDBACK LOOP

A nonlinear optical system with a spatially distributed feedback is co nsidered. The phase-amplitude transformation is performed in this syst em by a phase plate located in the Fourier plane of a confocal two-len s analyser. It is shown that introduction, into the feedback loop, of a geometric field transformation such as specular reflection of the fe edback distribution results in self-excitation of spatial structures i n the form of one-dimensional gratings. Experimental investigations ar e reported of the dependences, on the parameters of the problem, of th e following characteristics of the excited gratings: their amplitude, spatial frequency, and phase shift relative to the centre of the apert ure. The experimental results are compared with a theoretical analysis of the problem carried out in the first approximation.