Temporal modulation instability, transition to chaos in non-feedback biased photorefractive media

This paper surveys the theoretical dynamic model of chaotic regime in optical delayed feedback system; chaotic control parameters of optical input intensity and externally applied bias electric field are investigated. It is also shown that quasi-periodic state identified as temporal modulation instability can be deeply considered as a route to chaos through the evolution equation. Numerical solution of nonlinear Schrödinger equation as the universal model of modulation instability approves such claim. Pre-experiment based on optical delayed feedback system confirms theoretical model results and clarifies the crucial role of critical frequency as the competition point between optical bistability and the chaotic regime. Then, the simple experiment of non-feedback chaos control in Lithium Niobate photorefractive medium without delay indicates that quasi-periodic state -implies on temporal modulation instability- is also attainable and thus chaotic control can be achieved. The causal explanation of such behavior in slow response time Lithium Niobate photorefractive medium is analytically discussed as the generation of the internal feedback inside the medium.