Simulation analysis of influence of tilt phase error on coherent beam combination

A 4-channel model of coherent beam combination is established according to Fraunhofer diffraction theory, and the influence of tilt phase error on coherent beam combination with different duty ratios is studied. By using Eulers rotation, tilt angles of sub-beams are transformed into tilt phase errors, and then introduced into the combination model. Far-field intensity distribution of the combined beam with different duty ratios and tilt angles is calculated, and the influence of duty ratio and tilt angle is analyzed. Simulation results show that far-field intensity in the Airy disk decreases with increasing tilt angle, which means degraded combination effect. The dependencies of power in the bucket (PIB) and factor on tilt angle with different duty ratios are calculated. It is demonstrated that both of the two criteria degenerate when tilt angle increases. It is concluded that to reach the required criteria, tilt angles of sub-beams should be reduced within certain limit by utilization of correction component such as fast steering mirror.