FUNDAMENTAL SPACE-CHARGE FIELDS FOR APPLIED ALTERNATING ELECTRIC-FIELDS IN PHOTOREFRACTIVE MATERIALS

The fundamental component of the space-charge field in a photorefracti ve crystal is studied in the presence of an applied alternating electr ic field. A general equation for the amplitude of the fundamental spac e-charge field is derived, and a solution in integral form is given fo r the linear-modulation approximation. Exact and approximate analytica l solutions are presented for the case in which the applied field vari es in time as a square and a sine wave, respectively. The temporal var iation of the amplitude of the space-charge field is investigated for both waveforms of the applied field, and the oscillation amplitude dep endence on repetition frequency and interbeam angle is studied.