Photonic phase and time delay-steered arrays

Abstract

A switching unit for a photonic phased array for use in the microwave frequency bands uses lasers and other photonic devices to perform various functions in the phased array such that signals can be carried to the antenna elements on a single optical fiber. In one embodiment of the invention, a set of fixed phase shifters generates signals each having different phases. In the switching unit, each resulting signal, which is of a particular phase, modulates a laser of a different color. Each different laser color is thus associated with a given phase. Alternatively, time-delay units produce signals of different time-delay states which signals are then associated with lasers of different colors. The lasers are then used for selection of the signals to be applied to each element in the array. The laser signals are combined and carried on a single optical fiber to an optical network of tunable optical filters which can be located at the element level. The single optical filter allows the phase shifters and lasers to be located remotely from the antenna elements. Using an associated beam steering controller, the optical filters are tuned such that each element in the array has a predetermined signal to thereby adjust the time gradient across the array to steer the beam.