Patent ID: 7840108

Claim:
A light branching optical waveguide, comprising: at least one incident light waveguide (A), including an optical waveguide (a), optically connected to one end of a multi-mode optical waveguide, the multi-mode optical waveguide having a geometrical central axis, and wherein light of a basic mode propagating in said optical waveguide (a) enters on the geometrical central axis of the multi-mode optical waveguide; and output light waveguides (B) larger in number than the at least one incident light waveguide (A), optically connected to the other end of the multi-mode waveguide, the light branching optical waveguide being characterized in that: an intensity distribution of light entering from said optical waveguide (a), of the at least one incident light waveguide (A), into the multi-mode optical waveguide at a connecting surface of the at least one incident light waveguide (A) and the multi-mode optical waveguide, is asymmetric with respect to a geometrical central axis of said optical waveguide (a), said optical waveguide (a), of the at least one incident light waveguide (A), having a curved structure, with light entering from said optical waveguide (a) into said multi-mode optical waveguide, and with light having a wavelength entering at least two of said output light waveguides (B) from said multi-mode optical waveguide, so as to branch said light from the multi-mode optical waveguide having the same wavelength into each of said at least two of said output light waveguides (B), a branching ratio between quantities of light branched into each of said at least two of said output light waveguides (B) being substantially equal; and an extended line of the geometrical central axis of said optical waveguide (a) does not coincide with a geometrical central axis of the multi-mode optical waveguide.