Tiled Aperture Coherent Beam Combining Using Spatial Filter and Stochastic Parallel Gradient Descent (SPGD) Algorithm

Abstract

Coherent beam combining (CBC) technique using a spatial filter and stochastic parallel gradient descent (SPGD) algorithm was proposed. Estimations of CBC bandwidth for different numbers of beams and clusters, iteration steps and phase modulator bandwidths were presented. An apparatus was constructed and proof of principle experiments for 5 beams (2 clusters) in tiled aperture geometry, were performed. For phase modulator bandwidth of 1 kHz, the phase control bandwidth was theoretically estimated to be 10 Hz. The convergence time from the out-of-phase state was determined experimentally to be about 2 s.