Patent ID: 8923658

Claim:
An optical waveguide device comprising a Mach-Zehnder type waveguide formed on a substrate, wherein two waveguides input to an optical coupler on an output side of the Mach-Zehnder type waveguide have parallel linear parts arranged parallel to each other, a length of the parallel linear parts is not less than 100 μm and not more than 500 μm, and a gap between the parallel linear parts is not less than 0.5 μm and not more than 1 μm, wherein a waveguide of the optical coupler after being coupled by the optical coupler is a multi-mode waveguide, and wherein a waveguide which is output from the optical coupler is a three-branched waveguide including an output main waveguide and two output sub waveguides interposing the output main waveguide therebetween.