Multi-wavelength laser active coherent combination

A seed laser oscillating at different frequencies is proved to have the potential to mitigate the stimulated Brillouin scattering (SBS) effect in a fiber amplifier, which may increase the emission power of a coherent beam combination (CBC) system greatly. In this study, a basic mathematical model describing the multi-wavelength CBC is proposed on the fundamentals of CBC. A useful method for estimating the combination effect and analysing the feasibility and the validity of the multi-wavelength coherent combination is provided. In the numerical analysis, accordant results with four-wavelength four-channel CBC experiments are obtained. Through calculations of some examples with certain spectra, the unanticipated excellent combination effect with a few frequencies involved is explained, and the dependence of the combination effect on the variance of the amplifier chain length and the channel number is clarified.