Effect of plasticization on the performance of a photorefractive polymer

A systematic study of the effect of plasticization on the photorefractive performance of a poly(N-vinylcarbazole) (PVK) based polymer composite is presented, It is shown that N-ethylcarbazole (ECZ) can be used as an efficient plasticizer, leading to a large increase of the gain coefficient and the diffraction efficiency, which arises sorely due to an improvement in the orientational mobility of the dispersed nonlinear optical molecules. Phase separation, which is observed at samples with a high ECZ concentration, sets the upper limit. The steady state and the kinetics of the photorefractive gratings in the plasticized samples are discussed. The measurements suggest a high value of the saturation field and a response time that is Limited by photogeneration. A configuration is described, when prisms are employed to couple light into and from the sample, resulting into a higher two-beam coupling gain and diffraction efficiency.