Research on Phase-detecting Method for Coherent Beam Combining of Fiber Laser Array

Aiming at phase-detecting of each individual beam in coherent beam combining of fiber laser array,a new method based on Fast Fourier Transform(FFT) was developed to detect the phase shift between individual array leg and reference beam.It takes advantage of the movement of fringe-pattern and no frequency-shift component for reference beam is required in the system.Meanwhile,presented is a method that tailored acquisition interferogram to a multiple of fringe.It could reduce the effect of energy leakage on the phase detecting precision of FFT and thus improve the phase-detecting precision.Basic principle of the new phase-detecting method was described in detail.And simulating results show that the error of phase-detecting is less than λ/1000.