Investigation Of Beams Coupling In BSO Crystal Of The Sillenite Family

Bi₁₂SiO₂₀ (BSO) crystal is photorefractive material. Most of applications have relation with beam-coupling in photorefractive crystals. The character of the two-beam coupling and the four-wave coupling in BSO is investigated in this thesis.However, due to presence of optical activity, the electrooptic, piezoelectric and photoelastic effects in BSO, it is difficult to get the analytical results. For this reason, most previous works have ignored the effects of optical activity. We study beam-coupling in this paper considering the optical activity, the electrooptic, piezoelectric and photoelastic effects in BSO. By programming, we solve coupled-wave equations.Studying two-beam coupling, we get the gain curve of the signal beam in three cut planes in BSO when the polarization of signal and reference beams are parallel or not parallel. We take into account the change of the signal gain with the different beam intensity ratio. To the optimum polarization angle, we get the optimizing thickness of BSO and the angle of grating vector.Studying four-wave mixing, we get the phase-conjugate reflectivity in three cut planes in BSO when the polarization of signal beam and pump beam are parallel or not parallel. We take into account the change of the phase-conjugate reflectivity with the different pump beams intensity. At the same time, we get the optimizing thickness of BSO and the angle of grating vector to the optimum polarization angle.