Abstract

One of the most important parameters for applications of photorefractive crystals is the speed of the photoinduced grating build-up time. This time constant depends on the reduction state of the photoactive defects. One is primarily interested in a rapid redistribution of photoinduced charge carriers. This is the case in materials having a small concentration of trapping centers N_A where the drift length L_d= φµτe is large (comparable to the grating fringe spacing; µ: carrier mobility, τ=(γ_rn_a)⁻¹carrier life time, γ_R carrier recombination constant, E electric field). The relative concentration of donor (N_D) and acceptor centers (N_A) can be influenced by reduction treatment in oxygen octahedra ferroelectrics such as KNbO₃.

© 1987 Optical Society of America