Acousto-Optic Signal Processing For Radar Applications

Real-time convolvers and correlators having time-bandwidth products of about 10,000 have been achieved by utilizing the acousto-optic Bragg interaction. The large time-bandwidth products were achieved by using specially-designed large-bandwidth transducer arrays deposited onto large (~ 15-cm length), carefully polished crystals of lithium niobate (LiNbO3) and bismuth germanium oxide (BG0). A correlator in which a "live" signal is correlated with a previously stored acoustic signal, by use of the acousto-optic interaction, also has been demonstrated by using a new process for storing acoustic images in LiNbO3. Storage results from the interaction between a high-intensity, short-duration green laser pulse and a surface acoustic wave propagating in the material.