Novel acousto-optic systems for spectrum analysis and phased array radar signal processing

Citation

Riza, Nabeel Agha (1990) Novel acousto-optic systems for spectrum analysis and phased array radar signal processing. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/t6wf-tt49. https://resolver.caltech.edu/CaltechETD:etd-05302007-134330

Abstract

Novel acousto-optic systems for spectrum analysis and phased array radar signal processing are proposed. The pulsed source 2-D multiplicative time and space integrating spectrum analyzer is proposed and experimentally demonstrated. This architecture is simpler, physically smaller, and less sensitive to mechanical vibrations than the pulsed source 2-D additive Mach-Zehnder interferometer based spectrum analyzer. Simple and compact optical disk based systems for 1-D and 2-D spectrum analysis are presented. The high data packing density, angular motion, and parallel read out capability of optical disks is uniquely exploited to generate the very high time bandwidth product reference signals required for temporal spectrum analysis, that are otherwise difficult to generate using electronics. A continuous wave 1-D time integrating disk spectrum analyzer is successfully demonstrated in the laboratory. The limited dynamic range due to huge bias levels in interferometric time integrating processors is alleviated by using photorefractive crystals as real time bias removers. Continuous wave 1-D and 2-D bias free acousto-optic architectures for spectrum analysis are theoretically and experimentally investigated from a systems viewpoint.

Simple, compact, and powerful acousto-optic systems for control and signal processing in phased array radars are proposed that eliminate many system components like phase shifters, mixers, power dividers, and complex antenna feed networks, that are encountered in typical electronically controlled phased array radars. Via a single control parameter, namely frequency, the optical technique provides appropriately phased signals for transmission and reception in phased array antennas. The system is capable of continuous beam scanning, simultaneous multiple beam formation, and multi-target tracking, and can be integrated on a substrate to provide smaller and lighter phased array radars. Also, the system is resistant to electromagnetic interference (EMI), and signal phase shifts are independent of the radar carrier frequency employed. A 1-D linear phased array radar acousto-optic beam steerer is successfully demonstrated in the laboratory, and performance issues such as detector phase sampling error and phase linearity are highlighted. The linear array design is extended to planar and multiple linear arrays.

Thesis Files