SYSTEMATICS OF 2-WAVE MIXING IN A PHOTOREFRACTIVE POLYMER

The high-performance photorefractive polymer composite PVK:PDCST:BBP:C -60 is investigated in detail by use of optical two-wave mixing charac terization measurements in conjunction with the grating translation te chnique for determination of the photorefractive phase shift. A large effective trap density of N-eff = 1.5 x 10(17) cm(-3) is estimated fro m the dependence of the phase shift on the grating spacing and the app lied electric field. The theory of orientational enhancement is succes sfully used to explain the observed photorefractive response, and in t his low-glass-transition temperature system the modulation of the refr active index is shown to stem primarily from the spatial modulation of the birefringence. (C) 1998 Optical Society of America.