Abstract

We derive the impulse-response function of two-beam coupling amplification in the linear regime. Beam loss from absorption and beam fanning are also included. For gains greater than e⁴, the impulse time response has a peak. The location of the peak in time and its height are functions of the gain, loss, and time constant. Analytic results are obtained for the case of zero-signal beam loss. The case that includes loss from absorption and beam fanning is somewhat more complex. We have made measurements on barium titanate, both in the time domain and in the frequency domain, to verify the theoretical predictions. Whereas measures of the grating time constant are often focused on the material aspects, the impulse time response provides a good and consistent measure of the time constant that is relevant to the optical circuit performance of the two-beam coupling amplifier.

© 1990 Optical Society of America