Photorefractive Nonlinear Optics

This program succeeded in developing several photorefractive devices. One is a distortion compensating phase conjugate interferometer for the measurement of thin film thickness, refractive index and absorption coefficients. Also, we have investigated achromatic volume holography for adaptive optics applications. We have been working also on a device for passive mode locking of semiconductor lasers and have shown self pumped phase conjunction at 1.32 micrometers, the longest wavelength to date at which self- pumped phase conjugation has been observed. An understanding now exists of temporal instabilities in photorefractive phase conjugate mirrors. We are beginning to understand the effects of reduced spatial coherence in photorefractive devices, and using concepts developed in that work, we have analyzed our observations of high diffraction efficiency femtosecond two beam coupling in photorefractive crystals.