GLOBAL MAXIMA AND OPTIMAL GEOMETRY OF ACOUSTO-OPTIC INTERACTION IN TRIGLYCINE SULPHATE CRYSTAL

Abstract

The global maxima of the acousto-optic interaction are determined for monoclinic Triglycine Sulphate (NH₂CH₂COOH)₃H₂SO₄ (TGS) crystal by extreme surfaces method. As it is shown, the maximal value of the acousto-optic figure-of-merit M₂ is equal to 17.1×10^-15 s³/kg and is achieved in the case of isotropic i®i diffraction on the slow quasi-transversal acoustic wave. At that the incident light wave propagates in the direction determined by the angles q = 80^o, j = 135^o and polarized in q_m = 108^o, j_m = 48^o direction, the acoustic wave propagates along the direction q_a = 167.5^o, j_a = 160^o and polarized in q_f = 81^o, j_f =91^o one. The velocity of this wave is equal to 2313 m/s and the effective elastooptic coefficient p_ef is about 0.17. High values of the acousto-optic figure-of-merit and the transmittance in the spectral region down to 240 nm indicate TGS crystal as a promising material for acoutso-optic devices.