| 摘要 |
PROBLEM TO BE SOLVED: To provide a spot size converter and an optical waveguide coupler which, using a simple configuration, can reduce a coupling loss with a laser source that is flat in the horizontal direction regarding the optical waveguide coupler and a manufacturing method therefor.SOLUTION: On at least an optical input/output end face side, a first waveguide layer 3 of an optical waveguide having a laminate structure of first clad layer 2/first waveguide layer 3/second clad layer 4 is imparted a refraction index distribution in which the refraction index is the highest at center of the first waveguide layer 3 in the laminate direction of the laminate structure, and is provided with a concave-shaped protrusion 5, the cross section of which, that is orthogonal to the optical input/output end face and orthogonal to the principal surface of a substrate 1, has such a shape that the central part having the highest refractive index protrudes. |
