Real-time image processing by degenerate four-wave mixing in polarization sensitive dye-impregnated polymer films

Abstract

A real-time optical image processing scheme is described using degenerate four-wave mixing in thin films of polymethylmethacrylate thacrylate doped with the azo-based dye disperse red 1. A saturable optical nonlinearity based on the formation of polarization gratings caused by rotation of dye molecules within the polymer matrix is exploited. Selective erasure of spatial frequencies in the back focal plane of a Fourier-transform lens by a high intensity processing beam allows simple optical processing operations to be performed. Edge enhancement and bandpass filtering are demonstrated for amplitude objects, and a technique analogous to darkground illumination in microscopy enhances the visibility of a phase-object.