New noncollinear acousto-optic tunable filter using birefringence in paratellurite

Abstract

A new type of acousto-optic tunable filter was designed using anisotropic Bragg diffraction far off the optic axis in a TeO2 crystal. The acousto-optic figure of merit Me (n 6p 2/ρν3) of this filter is 1200 × 10−18 sec3/g. The filter properties are different for different values of the incident angle. For example, with 30°, tuning from 6500 to 4500 Å is obtained by changing the acoustic frequency from 72 to 117 MHz. At 6328 Å, the filter bandwidth is 8 Å and 100% transmission is obtained at an acoustic power of 170 mW for a square transducer.