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

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 pro blem 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 tange ntial component of the electric field and the normal components of the elec tric flux and current) is obtained under steady-state conditions. For the c omplete time domain the differential equation is solved numerically under t he approximation that the Debye length is small relative to the film thickn ess. It is shown that under the effects of attenuation and detuning the per pendicular component of the space charge field may considerably increase, T he space charge wave excited gives rise: to a non-zero steady-state perpend icular component of the space charge field that may be comparable with the parallel component. (C) 2000 Elsevier Science B.V. All rights reserved.