Real-time one-step phase locking with physics-informed phase estimator in multichannel coherent beam combining

Coherent beam combining (CBC) is an effective approach to surpass the power limitations of single fiber lasers, where precise phase control is essential. As the demand for higher power and more channels increases, achieving faster phase control becomes increasingly challenging for traditional methods. We propose a scheme termed physics-informed phase estimator (PIPE), which can be considered as a gray-box model merging locking of optical coherence by single-detector electronic-frequency tagging (LOCSET) and a well-trained neural network, that infers the phase differences between channels from the temporal intensity of the combined beam after assigning unique frequency tags to each sub-beam. Real-time one-step phase locking with a single photodetector is experimentally demonstrated in a four-channel CBC system by incorporating PIPE, achieving nearly an order-of-magnitude improvement in convergence time over LOCSET, with a residual phase of λ/45 and a combining efficiency of 98%. The results indicate that PIPE offers a promising solution for substantially enhancing phase control bandwidth in future CBC systems, especially for filled-aperture CBC systems.