LIGHT-DIFFRACTION BY HIGH-FREQUENCY ULTRASOUND, POLARIZED WAVE ALONG THE CRYSTAL AXIS

The problem of light diffraction by high frequency ultrasound in uniaxial crystals of 4mm, 42mBAR, 422, 4/mmm symmetry classes and corresponding classes of hexagonal systems is solved. The case is considered when sound propagates in the basal crystal plane, but sound vibrations are polarized along the crystal axis. It is shown that ordinary incident light wave do not at all diffract by sound wave of such configuration and diffraction of extraordinary incident wave takes place without rotation of the polarization plane. Dispersion law and amplitude of the first diffraction component are calculated. In Bragg resonance this amplitude has the same order-of-magnitude as the incident wave amplitude. But in the considered case the Bragg resonance is sharper than in the known cases of light diffraction by sound polarized wave in the basal crystal plane.