Noncollinear acousto‐optic filter with large angular aperture

A new type of noncollinear acousto‐optic filter with large angular aperture is described. By an appropriate choice of acoustic wave propagation direction, the momentum mismatch caused by the angular deviation of the incident light from the matching condition in a noncollinear interaction can be compensated by the angular change of optical birefringence. A TeO2 noncollinear acousto‐optic filter was constructed that had a half‐power bandwidth of 40 A at an f/4 (±7°) aperture. Tuning from 700 to 450 nm is obtained by changing the acoustic frequency from about 100 to 180 MHz. About 95% maximum transmission is obtained with an electrical power density of 1 W/cm2 applied to the transducer.