Kinetics of two wave mixing gain for moving grating technique in photorefractive BaTiO_3 crystal

Abstract

We present analytic expressions for time-dependent space charge field and two wave mixing gain under the external applied field accompanying the grating translation. The variations of complex space charge field are analyzed in a complex plane, and the explicit expressions for the resonance and optimum frequencies (or moving grating velocities), which maximize the magnitude and imaginary part of space charge field, respectively, are also obtained. In addition, two wave mixing experiment was conducted with a grating translation technique without the external applied field in a BaTiO(3) crystal and the transient behaviors of measured gain look like damped harmonic oscillations, showing excellent agreement with the theory for the entire time range.

Anisotropic build-up of photo-induced waveguides in biased photorefractive media

“…In addition, the experimental use of a bias electric field (or the presence of an intrinsic photogalvanic effect) leads to an additional symmetry breaking that favors the charge transport in that particular direction with respect to the others. All this leads to a complex build-up dynamics of the space-charge distribution [12,13,14,15], which, will depend also on the spatial geometry of the writing beam.…”