Abstract

Organic polymeric photorefractive materials are of current interest since it is possible to obtain materials with high electro-optic coefficients and low dc dielectric constants, yielding potentially high diffraction figures of merit, n³r_eff/ε. However, the process of geminate recombination can become very efficient in materials with low dc dielectric constants, limiting the rate of photogeneration of charges and thereby causing the buildup of the photorefractive grating to be slow. To address this problem, we have studied the process of geminate recombination on a picosecond time scale in a model polymeric photoconductor system using polarization-selective, field-dependent transient grating measurements. We describe our results from using a four-level model that includes the rates of geminate recombination, charge hopping, and field-assisted charge separation.

© 1992 Optical Society of America