Analysis of multi-wavelength active coherent polarization beam combining system.

In this manuscript, the multi-wavelength active coherent polarization beam combining (CPBC) system is investigated theoretically and experimentally. The relationship between the combining efficiency and the optical path difference (OPD), wavelength number, and the spectral density of power of the amplifier chains is analyzed and validated by establishing a two-channel multi-wavelength CPBC system. Further, the relationship between the combining efficiency and the voltage signal of the photo-detector is developed and validated experimentally. Finally, the feasibility of the active CPBC technique with complex spectral structures is verified and as high as 96% combining efficiency is obtained based on all fiber delay lines to compensate the OPD between different channels, which is crucial for further power scaling of the CPBC system. Our theoretical analysis offers a useful approach to estimate the influence of OPDs, wavelength number, and the spectral density of power of the amplifier chains on multi-wavelength active CPBC system.