Numerical and experimental study on coherent beam combining of fibre amplifiers using simulated annealing algorithm

We present the numerical and experimental study onthe coherent beam combining of fibre amplifiers by means of simulatedannealing (SA) algorithm. The feasibility is validated by the MonteCarlo simulation of correcting static phase distortion using SAalgorithm. The performance of SA algorithm under time-varying phasenoise is numerically studied by dynamic simulation. It is revealedthat the influence of phase noise on the performance of SA algorithmgets stronger with an increase in amplitude or frequency of phasenoise; and the laser array that contains more lasers will be moreaffected from phase noise. The performance of SAalgorithm for coherent beam combining is also compared with a widelyused stochastic optimization algorithm, i.e., the stochasticparallel gradient descent (SPGD) algorithm. In a proof-of-conceptexperiment we demonstrate the coherent beam combining of two 1083~nmfibre amplifiers with a total output power of 12~W and 93%combining efficiency. The contrast of the far-field coherentlycombined beam profiles is calculated to be as high as 95%.