Inelastic light scattering on two degenerated hypersonic waves: The switching effect

Inelastic light scattering by two hypersonic acoustic waves has been investigated theoretically. The calculated scattering efficiency shows a switching effect for a specific configuration, when both acoustic waves possess the same velocities and frequencies but have perpendicular polarizations. All the calculations were performed for both the hypersonic and the ultrasonic acoustic ranges in a LiTaO₃ crystal. Hypersonically measured elastic constants appear more relevant for investigating the effect that results from scattering photons on acoustical phonons near the origin of the first Brillouin zone.