Optical instabilities in the output light from a bistable optical device (BOD) with a delayed feedback was predicted by Ikeda . Gibbs et al.  gave the first experimental verification of this type of instabilities. From that time several groups have studied the instabilities of the BOD for different relations between the delay time tR and the time constant ح of the system. In a previous paper  an empirical and analytical study of instabilities in hybrid BOD was reported by us. The employed set up is shown in Fig. 1.