Optimization of Diffraction Efficiency and Gain for Two-Wave Mixing in Cubic (111)-Cut Photorefractive Piezocrystals

The dependence of the diffraction efficiency of holograms and the effective gain of the signal wave on the polarization and orientation angles is investigated for two-wave mixing in transmission geometry in cubic (111)-cut photorefractive piezocrystals (classes 23 and 43 m). It is shown theoretically and experimentally that in 2.1 mm thick BSO crystals (class 23) the piezoelectric effect leads to an increase of the diffraction efficiency by 70% and of the gain by 30% for certain values of the polarization and orientation angles. Without the piezoelectric effect the diffraction efficiency does not depend on polarization and orientation angles in both optically active (BSO) and optically inactive (GaAs) crystals, whereas the effective gain depends on polarization and orientation angles while its maximum value remains constant. It is found that for thickness of BSO crystal 8.2 mm the diffraction efficiency and the effective gain do not depend on polarization of reading light. For the first time the experimental dependence of maximum diffraction efficiency of hologram in (111)-cut BSO crystal on the orientation angle θ is found. The results of the experiment confirm correctness of chosen physical model of the diffraction.

Keywords:

• Two-wave Mixing
• Photorefraction
• Piezoelectric Effect
• Optical Activity