Study on optical heterodyne detection with photorefractive adaptive crystal

Abstract

A photorefractive adaptive optical heterodyne detection system is proposed. Its principle is introduced and typical numerical calculation is illustrated, which includes the reference beam output power and minimum detectable signal power versus system global power ratio, the effect of crystal coupling strength on reference beam output power and minimum detectable signal power, and the minimum detectable signal power versus nonlinear coupling strength. Several key factors which affect the system characteristics strongly are pointed out. In the proposed system, only one photorefractive crystal is used to attain optical heterodyne detection. The system features simple structure, low noise and high responsibility. It also answers two key questions of heterodyne detection: 1) phase distortion; 2) coherent length of light source.