Optical phase locked loop (OPLL) module for use as a 9 GHz source in phased array communications antennas

Coherent optical beamforming is particularly advantageous in multi-beam mobile phased array communications. Systems of this type employ a pair of phase locked optical carriers with a difference frequency equal to the required microwave signal. In this work a packaged diode-laser optical phase locked loop (OPLL) sub-system has been constructed for evaluation in a proof-of-concept optical beamforming system. The loop has been implemented with laser diodes, micro-optics and wide bandwidth electronics to give optimum phase noise performance.