Study on the effect of nonuniform polarization angles on coherently combined fiber lasers

The effect of nonuniform polarization angles on coherently combined fiber laser beams is analyzed numerically by using statistical methods. Beam propagation factor (BPF) is used to evaluate the quality of the combined beam. The numerical analysis shows that the reduction in beam quality caused by nonuniform polarization angles is relatively small for a phased fiber laser array. The effect of the nonuniform polarization angles and the vacancy factor are decoupled. Enlarging the array number does not weaken the influence of polarization-angle fluctuation. The results above are valid for an array with a large number of lasers or an array consisting of lasers with polarization-angle fluctuation. The mechanism of beam quality degeneration due to nonuniform polarization angle is also discussed.