OPTICAL COUPLER, LASER DEVICE, AND TAPER FIBER

摘要

PROBLEM TO BE SOLVED: To implement an optical coupler in which NA of light emitted from a taper fiber is smaller than that in conventional optical couplers.SOLUTION: A taper fiber 13 has a high-refractive index region 131 which is formed in a core having a refractive index nand has a refractive index larger than n. An emission end surface 12b of each GI fiber 12 and an incidence end surface 13a of the taper fiber 13 are joined so that at least a part of the emission end surface 12b of the GI fiber 12 overlaps a cross section of the high-refractive index region 131.SELECTED DRAWING: Figure 1