All-fiber active coherent combining via a fiber combiner

We present a new approach for an all-fiber coherent beam combining by active phasing a fiber combiner. The combined advantages of all-fiber format and large output core of the fiber combiner provide a robust performance and higher power handling capability for coherent beam combining. The active phase control and beam cleanup technique are implemented to convert a continuously changed and diverged output multimode beam into an in-phase mode and near-diffraction-limited beam. Experimental results show that the quality evaluation function of the combiner’s output beam is increased from 1.02 to 3.7. Meanwhile, the power in the bucket has increased more than a factor of 2.28. This proof-of concept experiment validates the feasibility of all-fiber and active coherent beam combining using a fiber combiner for high power together with high beam quality.