Space-charge field induced in a photorefractive crystal with an applied square-wave electric field for large contrast of an interference pattern

In the quasi-static approximation, the nonlinear equation for the space-charge field Esc formed in a photorefractive crystal with an applied square-wave voltage under the action of light with an inhomogeneous transverse intensity distribution is derived. The spatial spectrum of the field Esc induced in a Bi12TiO20 crystal with typical values of the acceptor density NA and of the product of the electron mobility by the recombination time μτR is analyzed. An approximate analytical solution of the nonlinear equation is derived in the case in which the amplitudes of spatial harmonics of the spectrum Esc form a nonmonotonic sequence. The spatial distribution of the induced electric field is calculated numerically for crystals with different parameters NA and μτR. © 2001 Plenum Publishing Corporation.