Two-dimensional optical beam-forming networks

This paper presents recent advances toward the experimental demonstration and the far field pattern characterization of an optically controlled phased array antenna operating at 3 GHz. The 2D optical architecture is based on polarization switching by N (N equals 6) spatial light modulators of pxp pixels (p equals 4). It provides 2N-1 time delays values and an analog control of the 0 to 2(pi) phase for each of the pxp microwave signals actuating an active antenna. These signals originate from the coherent detection of a dual frequency laser beam obtained with an acousto-optic frequency shifter. Furthermore, we also present the principle of a new photodetector based on the synchronous drift of photogenerated carriers with a moving interference pattern. This moving pattern results from the interference of the two components of the dual frequency optical carrier of the microwave signal used in the above architecture. It provides a large detection volume which could yield a high saturation intensity. A theoretical analysis is detailed and followed by an experimental demonstration in GaAs at a frequency f equals 210 MHz.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.