Switched-Grating Devices for Phased Array Radar Applications

Novel true-time-delay optical beamforming networks for phased array antennas are devised using nonlinear high efficiency grating technology for free space switches. The switchable gratings are formed using nonlinear volume phase diffraction grating composites. The resulting optical time delay networks include both addressable free space delay lines and uniform delay switching fabrics to route optical channels through desired members of an array of guided wave optical delay devices. An additional nonlinear device is added that selectively absorbs weak signals that leak through nonselected channels due to imperfect diffraction efficiency, scatter, etc. while transmitting the signal in the selected path with minimal attenuation. After refining initial device designs, a computer model of these devices is constructed using volume diffraction and nonlinear optics theory. A prototype network is designed and the model is used to demonstrate feasibility of the concept and design. Experiments are included to study improved material systems. Resulting networks are expected to possess advances in switch isolation (thus lower signal distortion) and insertion loss (yielding greater radar dynamic range). Government markets include radar beamforming networks and private sector opportunities exist for the technology as reconfigurable interconnects.