Two regimes of wide angle acousto-optic interaction in tellurium dioxide single crystals.

The paper presents results of investigation of wide angle acousto-optic (AO) diffraction based on light beams propagating in birefringent crystals far away from optical axes and also close to the optical axes. A comparison of the two cases of wide angle interaction in tellurium dioxide crystal is carried out. Advantages and drawbacks of the far-off axis (FOA) diffraction are examined in the paper. Possibility of application of the FOA diffraction in imaging AO filters is discussed. Results of theoretical consideration of the problem are experimentally confirmed in a paratellurite filter using a slow shear acoustic wave propagating in the (11¯0) plane of the crystal at the angle α=10° relative to the axis [110].