Acousto-optic multifrequency modulators: reduction of the phase-grating intermodulation products

Abstract

The multifrequency acousto-optic modulator efficiency is limited mainly by the two-tone, third-order intermodulation products. We show here that a suitable anisotropic interaction can greatly reduce this undesirable effect. Numerical computations have been drawn for a paratellurite acousto-optic cell, and it is shown that a reduction of ~ 16 dB can be reached, limited by the acoustic nonlinearity intermodulation products. A specific method for experimental validation, based on optical heterodyning on a photodetector, is presented. The experimental results agree well with the theoretical ones.