Collinear acousto-optic filter on the base of paratellurite crystal

The effect of collinear diffraction of a bounded optical beam by ultrasonic wave has been observed in paratellurite crystal in direction [110] that is forbidden for acousto-optic interaction in the case of plane waves. It has been found that the efficiency of the diffraction increases with the growth of the divergence of light. The dependences of the intensity of the diffracted light on acoustic amplitude and frequency have been also investigated. The ratio of the carrier frequency of the diffraction and the frequency bandwidth gives a resolution value R ∼ 3000. A complicated transversal structure of the diffracted optical beam has been also examined in the paper. The carried out calculations showed that the decrease of ultrasound in TeO₂ crystal at the frequencies about 150 MHz influences strongly the parameters of the collinear diffraction. It results in the decrease of the efficiency of diffraction and in the broadening of the bandwidth of the device. The attenuation coefficient in paratellurite has been found experimentally.