ACOUSTOOPTIC SYSTEM FOR THE GENERATION AND CONTROL OF TUNABLE LOW-FREQUENCY SIGNALS

An optically efficient interferometric acousto-optic architecture for the tunable generation and control of low-frequency signals is propose d using two radio frequency (rf) or microwave band Bragg cells in an i n-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 optical detector. Tunable 1- to 15-MHz ultrasonic band signal generat ion is demonstrated with rf Bragg cells, showing high (107 dB/Hz) carr ier-to-noise ratios. This free-space interferometric acousto-optic sys tem with two collinear output beams with a relative color shift is req uired for making a compact, lightweight, and powerful optical platform for baseband/low-frequency optical signal processing and control func tions, such as required in advanced phased-array systems used in sonar , medical, and industrial applications. (C) 1996 Society of Photo-Opti cal Instrumentation Engineers.