Collinear acousto-optic interaction of divergent beams in paratellurite crystal

Abstract

Theoretical and experimental investigation of collinear diffraction of divergent optic beams by ultrasonic waves near by the direction [110] of paratellurite crystal has been carried out. The diffraction has been examined in direction [110] forbidden in TeO2 for acousto-optic interaction in the case of plane waves. It has been shown that the collinear diffraction along this direction exists only for divergent light and sound waves while efficiency of the diffraction increase with the growth of the divergence. The effect has been examined at the acoustic frequency f≈ 149 MHz and the wavelength of the non-collimated light λ=633 nm with the optical spreading up to 4°. A collinear acousto-optic filter on paratellurite applying the diffraction has the length of interaction l=2.7 cm. It has been proved the acoustic attenuation causes a decrease of efficiency of the diffraction and a broadening of a bandwidth of the device. The spectral resolution value as high as R~3000 has been obtained a λ=633 nm. The diffraction efficiency I1/I0≈0.8 and the wide angle aperture Δφ≈4° give perspectives to use the collinear diffraction in filters on the base of TeO2 crystals.