Optical trap activation in a photorefractive polymer

Optical trap activation has been observed to increase the steady-state diffraction efficiency by a factor of 3 in a photorefractive (PR) polymer, poly(methylmethacrylate):(l,3-dimethyl-2,2-tetramethylene-5-nitrobenzimidazoline) (PMMA:DTNBI). The increased diffraction efficiency is accompanied by an increase in the PR storage lifetime but also by an increase in the characteristic grating growth time of the PR grating. The optical activation of the deep trapping sites is observed to be a sublinear function of the optical irradiation power. Both spatially uniform trap activation and spatial patterning of the photorefractive response of the material are demonstrated. © 1994 Optical Society of America.