Analysis of Delay Resolution for a True Time Delay Photonic Beamformer

摘要

The problem of obtaining a true time delay photonic beamformer has recently beena topic of great interest. This report examines the design, construction, and testing of a dynamic optical processor for the control of a 20-element phased array antenna operating at L-band (1.2-1.4 GHz). The approach taken here has several distinct advantages. The actual optical control is accomplished with a class of spatial light modulator known as a segmented mirror device (SMD). Optical splitting is efficiently accomplished using a diffractive optical element. The actual time delay is achieved using a single acoustooptic device for all the array elements. The topological configuration is an optical heterodyne system; hence high, potentially millimeter wave center frequencies are possible by mixing two lasers of slightly differing frequencies. Finally, the entire system is spatially integrated into a three dimensional glass substrate. Though the system is presently being configured as a beamformer, it has the ability to operate as a general photonic signal processing element in an adaptive (reconfigurable) transversal frequency filter configuration. Such systems are widely applicable in jammer/noise cancelling systems, broadband ISDN, and for spread spectrum secure communications.