ACOUSTOOPTIC MULTIFREQUENCY MODULATORS - REDUCTION OF THE PHASE-GRATING INTERMODULATION PRODUCTS

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