Phased array beam controller using integrated electro-optic circuits

Abstract

A photonic device for controlling phased array beam direction includes an electro-optic substrate; a plurality of waveguides formed in the substrate, each of which is capable of simultaneously propagating light signals with orthogonal polarizations; an input waveguide for inputting into each one of the plurality of waveguides a pair of copropagating polarized light signals having orthogonal polarizations and different frequencies; a plurality of electrodes on the substrate configured to phase shift the signals traveling through each waveguide by a different amount in response to applied voltages, thereby creating phase shifted polarized signals; and means for combining the phase shifted polarized signals within each one of the waveguides and propagating these combined signal to an antenna element. The basic operating principle of the invention is based on the differential phase shift between optical waves of orthogonal polarizations traveling in an electro-optic optical waveguide. This differential phase shift is directly proportional to the voltage applied to a control electrode and to the length of that electrode. If the two optical waves are slightly offset in optical frequency, they produce a beat frequency when photodetected whose phase shift equals the optical differential phase shift. An array of such phase shifters forms the basis for the photonic beam controller of the invention.