Comprehensive investigation of LOCSET and SPGD algorithms in coherent beam combining applications

Locking of Optical Coherence by Single-Detector Electronic-Frequency Tagging (LOCSET) and Stochastic Parallel Gradient Descent (SPGD) algorithms, the main active phase control methods suitable for coherent beam combining (CBC) systems, are analyzed comprehensively under various noise conditions, and the impact of different parameters on control performance is studied, which reveals that the optimal parameters under dynamic perturbations deviate obviously from those achieved in static condition. Moreover, the problem of integration time susceptibility of LOCSET is addressed and high-speed LOCSET loop is prospected. Under the optimal parameter conditions, the channel scalabilities of the two methods are compared and the hardware requirements are discussed, indicating that LOCSET is more promising for large-scale CBC applications. This work may provide useful guidance for choosing a suitable algorithm and optimizing its parameters according to the real noise condition and system scale.