Acousto-optic frequency shifted comb laser-based micro-Doppler detection for moving target identification.

Abstract

We present a preliminary experimental demonstration of an acousto-optic frequency shifted (AOFS) comb laser-based micro-Doppler detection system for moving object identification. The AOFS comb laser was constructed by successively frequency shifting a single-frequency seed laser at 1063.8 nm using an acousto-optic modulator in an amplified fiber loop, which resulted in a stable pulse output with a pulse repetition rate around 150 MHz and pulse duration of about 200 ps. The AOFS comb pulse was amplified and then directed through a fiber circulator first and then an optical lens onto a moving object, which featured both linear translation and rotation. The micro-Doppler signal of the rotation was derived from the heterodyne detection of the pulse echo comb laser and the continuous-wave single-frequency local laser. It is believed that such an AOFS comb laser-based sensing system is of great potential for micro-Doppler detection of high-speed targets owing to its long-term stability and compactness.