Optical beamforming for receiver phased array systems using periodic slow-wave structures

In this paper an optical beamforming algorithm for receiver phased array antennas is proposed by tuning the group delay of cascaded ring resonators. A condition for maximally flat group-delay is derived to increase the useful optical bandwidth and take the most advantage of the squint-free beamforming. Using this condition the beamforming problem is stated as a constrained optimization problem with the objective of maximizing the received power by a phased array antenna. An iterative solution based on gradient estimation is proposed for the beamforming problem. It is shown that this algorithm converges rapidly with a negligible residual error.