Anisotropy of an acousto-optic figure of merit for NaBi(MoO4)2 crystals

We develop a technique for analyzing the anisotropy of an acousto-optic figure of merit for crystals belonging to tetragonal symmetry groups 4/m, 4, and (4) over bar. The technique is based on phenomenological relations that describe anisotropies of the effective elasto-optic coefficients and the acoustic wave velocities. Our approach is verified on the example of NaBi(MoO4)(2) crystals for all possible types and geometries of acousto-optic interactions. We list and characterize the acousto-optic interaction geometries at which the maximal acousto-optic figures of merit are reached for both isotropic and anisotropic interaction types. Finally, we show that the acousto-optic efficiency of NaBi(MoO4)(2) originates mainly from large elasto-optic coefficients. (C) 2016 Optical Society of America