EFFECTS OF SATURATION ON THE NONLINEAR INCOHERENT-ERASURE JOINT-TRANSFORM CORRELATOR

A photorefractive nonlinear joint-transform correlator based on the in coherent-to-coherent conversion is presented and analyzed. The nonline arity of this incoherent-erasure joint-transform correlator (IEJTC) is tunable from the classical-matched to the phase-extraction limit. Cor relation peak intensity, sharpness, and discrimination ability increas e with the incoherent beam intensity. At easily achievable incoherent- to-coherent beam intensity ratios the IEJTC has its optimal performanc e, at which the IEJTC approaches the performance of the inverse filter for clean inputs and surpasses the inverse filter performance for noi sy inputs. We examine this nonlinearity by using the transform method of analysis and computer simulations. Our study focuses on the effect of saturation on the correlation ability. Our results provide an expla nation of why extending the severity of saturation by increasing the i ncoherent-to-coherent intensity ratio beyond a turning point results i n lower optical efficiency, degraded correlation peak, and increased h igher-order harmonics. (C) 1996 Optical Society of America