Acousto‐optic system for the generation and control of tunable low‐frequency signals

Abstract

An optically efficient interferometric acousto-optic architecture for the tunable generation and control of low-frequency signals is pro- posed using two radio frequency (rf) or microwave band Bragg cells in an in-line configuration. Critical beam deflection optics, such as a dove prism, ensure that the interfering beams are collinear and stationary, thus providing the high heterodyning efficiency required at the fixed op- tical detector. Tunable 1- to 15-MHz ultrasonic band signal generation is demonstrated with rf Bragg cells, showing high (107 dB/Hz) carrier-to- noise ratios. This free-space interferometric acousto-optic system with two collinear output beams with a relative color shift is required for mak- ing a compact, lightweight, and powerful optical platform for baseband/ low-frequency optical signal processing and control functions, such as required in advanced phased-array systems used in sonar, medical, and industrial applications. © 1996 Society of Photo-Optical Instrumenta- tion Engineers. Subject terms: acousto-optics; phased arrays; low frequency; ultrasonic signals; control.