All fiber 7 \tiems 1 signal combiner with high beam quality for high power fiber

All-fiber signal combiner is a key component for augmenting the fiber laser power. Presently the reported 7 \times 1 signal combiners are all have output fibers with core diameters larger than 100 \mu m. In order to improve the beam quality of the combiner, a fiber with smaller core of 50 μm diamete