Experimental Phase Stabilization of a 397-Channel Laser Beam Array Via Image Processing in Dynamic Noise Environment

A phase-locking module is firstly validated for coherent beam combining (CBC) systems of near 400 laser beams in dynamic noise environment. It is based on a 2-dimensional image processing in the phase-locking module to calculate the piston phase of the laser array in the CBC systems. Through the designed phase-locking module, the piston phase distribution of the laser array can be corrected simultaneously, accurately, and rapidly as fast as ${\sim }$ 2000 Hz. Proof-of-concept experiment is demonstrated for coherent beam combining of up to 397 fiber laser emitters based on the designed phase-locking system to correct the phase noises measured from a real fiber amplifier below 1 kHz. The ratio of power in the Airy disk is as high as 59.51 % when the phase compensation is carried out for the piton phase noise measured in a kW-class fiber amplifier. The phase residue error in the close-loop is better than ${\lambda }$/31.