Optical Field Transmission Analysis of an All-Fiber Signal Combiner With a Dumbbell Shape

In this paper, the optical field transmission characteristics of an all-fiber signal combiner with a dumbbell shape and its application in laser beam combining are analyzed theoretically. Based on the three-layer waveguide model, the mode characteristics of a tapered multi-core fiber and a tapered single core fiber are analyzed respectively. On this basis, the working principle of an all-fiber signal combiner with a dumbbell shape is introduced from the perspective of mode evolution. The finite-difference beam propagation method is used to numerically analyze optical field envolution process in the combiner. Influences of the waist diameter, taper length and geometric arrangement are analyzed in detail. The calculation results show that an all-fiber signal combiner with a dumbbell shape can realize high brightness laser beam combining and the beam quality can reach the theoretical limit.