Anomalous diffusion in dynamic reflection grating recording in the photorefractive polymers

Summary form only given. Holographic grating recording in photorefractive polymers (PRP) is rapidly growing from proof-of-principle demonstrations to more practical schemes. The main obstacle for practical use of PRP is the necessity to apply a high electric voltage (5-7 kV) to 100-/spl mu/m thick polymer film to insure high-efficiency recording. A conventional scheme of recording is a transmission geometry with slant gratings when a bisector of two recording beams is tilted with respect to the normal to polymer film (and to the direction of the applied field). We suggest a new reflection-type geometry and experimentally show (with HeNe laser) that a diffraction efficiency up to 7% can be obtained without an external electric field in poly(N-vinyl carbazole) (PVK) based PRP. For interpretation of our experimental results we have developed a model of grating recording including local molecular polarization changes and two-dimensional diffusion.