Patent ID: 9429706
Filing Date: 2016-08-30
CPC Classification: G02B

Claim Text:
1. An optical waveguide coupler, comprising: a substrate; and an optical waveguide of a multi-layer structure of a first clad layer/a first core layer/a second clad layer, at least, on an end surface side of an optical input and output provided on the substrate, characterized in that the first core layer has such a distribution of the refractive index that the refractive index is the highest at the middle of the first core layer in a stacking direction of the multi-layer structure, the refractive index of the first core layer in a portion contacting with the first clad layer and the second clad layer is lower than the refractive index of the middle of the first core layer, and the first core layer has such a protrusion in a convex form that the center portion having the highest refractive index protrudes in a cross section that is perpendicular to the end surface of the optical input and output and perpendicular to the main surface of the substrate.