Optical dissipative structures with a controlled spatial period in a nonlinear system and with a Fourier filter in a feedback loop

Abstract

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