Abstract

Coherent guided-wave optical systems offer significant advantages for use with phased-array drive and readout schemes. Single-side-band modulation of received fields allows for optical mixing of the microwave signals through Butler-matrix techniques with the attendant low loss and high resolution of optics. Such methods obviate the need for adaptive antenna processing and also produce a baseband signal at the output of an optical detector. Coherent drive allows for phase shifting to be performed at optical, rather than microwave, wavelengths, thereby allowing for compact, high- bandwidth true-time-delay, integrated-optical phase shifting. Heterodyning at the antenna-element end allows one to use a high-power locked local oscillator, thereby minimizing any need for at-element microwave amplification. Many of the elements necessary to realize such photonic array control schemes already exist and, in the near future, should become monolithically integrable, allowing for fiber-compatible modular construction of various drive schemes. We will discussion the performance of the various system elements, including those fabricated and tested in our laboratory as well as others for which data is available, and thereby project eventual system performance in terms of the standard phased-array performance measures.

© 1990 Optical Society of America