OPTICAL BRANCHING CIRCUIT

PROBLEM TO BE SOLVED: To facilitate easily adjustment of a light axis and to prevent lowering in yield of an optical branching circuit which is connected with a light output end face of an optical waveguide circuit or the optical branching circuit, and branches an input light. SOLUTION: The optical branching circuit has an input optical waveguide 4 which outputs a light input from a light input end face S1to the light output end face S2, a taper optical waveguide 5 whose end face is connected with the light output end face S2and whose width spreads in a predetermined angle, and branch optical waveguides 6 and 7 connected with the other end face of the taper optical waveguide 5 at a predetermined branch angle. When a propagating constant of a leakage mode is βL, a propagating constant of a fundamental mode is β0and a meandering cycle is Λa, and Λ=2π/(β0-βL), an optical waveguide length L from a position causing an occurrence of leakage mode to the light output end face S2is set to almost an integer number times of Λ/2. COPYRIGHT: (C)2004,JPO