Efficient acousto-optic crystal, TlInS₂: acoustic and elastic anisotropy

We have studied experimentally the acoustic wave velocities for TlInS₂ crystals and determined all components of their elastic stiffness and compliance tensors. It has been found that TlInS₂ reveals small elastic anisotropy with respect to normal mechanical stresses. The compliance components S₄₄ and S₅₅ are very large, thus suggesting that the TlInS₂ crystals are extremely compliant to the shear stresses in the cleavage plane. We have also revealed that the velocities of some of the quasi-transverse waves are very low (∼725  m/s), leading to extremely high acousto-optic figures of merit (∼2200-9000×10^-15  s³/kg). This implies that the crystals under study can prove to be a very efficient acousto-optic material.