MODULATION DEPENDENCE OF THE PHOTOREFRACTIVE RESPONSE WITH MOVING GRATINGS - NUMERICAL-ANALYSIS AND EXPERIMENT

The photorefractive response with moving gratings is investigated both numerically and experimentally under varied fringe-velocity and modul ation-depth (m = 0.002 to m = 1) conditions. The numerical analysis em ploys a finite-difference technique to model photorefractive grating d ynamics. The magnitude and the phase of the space-charge field are pre sented in detail as functions of modulation depth, fringe velocity, an d crystal parameters. Energy transfer and diffraction efficiency are f ound to exhibit different response characteristics with modulation and fringe velocity. Numerical results for two-wave mixing are generalize d through analytical expressions that approximate the numerical soluti ons. Illustrative experimental results are presented for Bi12SiO20.