Integrated Self-Routing True Time-Delay for Optically Controlled Phased-Array Sensors

We propose to develop a new self-routing electronically tuned optically controlled true-time delay network based on the recirculating photonic filter concept. This feed architecture represents a major departure from conventional approaches that use the optical fiber merely as a delay line. This system achieves complete electrically tunable true-time delay which requires but one single frequency laser, thus eliminating the need for a fast tunable laser which is required in alternative approaches based on the Bragg fiber grating or dispersive fibers. Further, the total absence of any switches and associated switches and associated switch insertion loss is a key advantage that ensures easy scalability of this scheme to antenna arrays with high element count. The system we propose uses the waveguard grating in a unique recirculating configuration that enables the optical carrier wavelength to map to a particular true-time delay. In addition a totally novel self routed electrical tuning of the grating is proposed to switch the true-time delay. The unique choice of a silicon foundry compatible integrated optic waveguide technology(silicon-on-insulator) and IC compatible fabrication process promises reliable low-cost self routed time-delay chips. Our approach ensures, low-loss, broadband, scalable true-time delay architecture that can be easily extended to 2-D arrays. In addition the proposed technology is rugged. ultra compact, and low cost. In the phase I effort, we will design, fabricate and characterize a prototype 8-channel (3-bit) device.