Optical fiber of the optical fiber coupler for fiber-optic and coupler

摘要

PROBLEM TO BE SOLVED: To provide an optical fiber coupler whose excessive loss is sufficiently reduced.;SOLUTION: Optical fibers 10 and 20 used for the optical fiber coupler 1 have a specific refractive index difference Δn(r)≤Δn_peak[1-(r/a)3], where (r) is a radial distance from the center of the optical axis, An(r) is the specific refractive index difference at positions (r) in core parts 10a and 20a based upon the refractive indexes of clad parts 10a and 20b provided around the core parts 10a and 20a, and (a) is a core radius, providing that the specific refractive index Δn(r) has a peak value Δn_peak at a position r_peak. Further, the refractive indexes of the clad parts 10b and 20b gradually decrease radially outwards.;COPYRIGHT: (C)2003,JPO