Investigation of the influence of mode-mismatch errors on active coherent polarization beam combining system.

In this manuscript, we theoretically and experimentally investigate the influence of mode mismatch errors on active coherent polarization beam combining (CPBC) system. Firstly, by incorporating a piezo-mounted mirror (PMM) to generate artificial tilt phase aberrations, we design an experimental system to theoretically and experimentally investigate the influence of mode-mismatch errors induced by tilt phase aberrations on the combining efficiency of CPBC system. Further, by employing a spatial light modulator (SLM) to impose higher-order phase aberrations, the impact of mode-mismatch errors induced by higher-order phase aberrations on the CPBC system is also studied specifically. In the situation of adding each man-made aberration, experimental results correspond well with the theoretical ones. By theoretical and experimental analysis, we also show that the combining efficiency of the CPBC system is susceptible to the phase mismatch errors among different channels while has high tolerance on the intensity mismatch errors, which is compatible with the analysis in other CBC configurations. Besides, experimental results also show that the combining efficiency of the CPBC system is independent on the modulation frequency of dynamical tilt phase aberrations. Our analysis and designs provide useful approaches to diagnose the influence of mode-mismatch errors on CPBC system and optimize the whole CPBC system specifically.