All-fiber 7 × 1 signal combiner with high beam quality for high-power fiber lasers

All-fiber signal combiner is a key component for augmenting the fiber laser power. Presently the reported 7 × 1signal combiners are all have output fibers with core diameters larger than 100 μm. In order to improve the beam quality of the combiner, a fiber with smaller core of 50 μm diameter is chose to be the output fiber. An all-fiber7 × 1 signal combiner is fabricated with measured power transmission efficiency around 99% for each port. The beam quality is improved and the measured M2 are around 6 which are matched well with the theoretically calculated results.