Optical grating recording in lossy photorefractive thin films: space charge waves in 2D geometry

Abstract

Dynamic grating formation in lossy PR thin films is investigated when the incident beams are detuned and the applied electric field is parallel with the grating vector. Starting with a two-dimensional formulation of the problem a differential equation, first order in time and fourth order in space, is derived for the parallel component of the electric field. An analytic solution of this equation subject to the boundary conditions (for the tangential component of the electric field and the normal components of the electric flux and current) is obtained under steady-state conditions. For the complete time domain the differential equation is solved numerically under the approximation that the Debye length is small relative to the film thickness. It is shown that under the effects of attenuation and detuning the perpendicular component of the space charge field may considerably increase. The space charge wave excited gives rise to a non-zero steady-state perpendicular component of the space charge field that may be comparable with the parallel component.