The transfer function and impulse response of photorefractive two-beam coupling

The transfer function and impulse response of photorefractive two-beam coupling are derived in the undepleted pump approximation. For sufficiently strong coupling Gamma L, the impulse response features a broad delayed output pulse. In the limits of negligible and strong absorption alpha L, this coupling threshold reads Gamma L/sub thr/=4 and Gamma /sub thr/=2 alpha , respectively. The time delay and pulse height are functions of the coupling Gamma L, the photorefractive time constant tau , and the effective absorption alpha L. Experiments on a BaTiO/sub 3/ crystal measuring the absoluted square of its transfer function and the impulse response are used to determine the coupling and time constant.>