| 摘要 |
PROBLEM TO BE SOLVED: To obtain the grating coupler which can suppress waveguide loss due to wavelength variation of a light beam as much as possible without machining a waveguide layer specially. SOLUTION: The grating coupler is constituted by providing the optical waveguide layer 15 on a substrate 10 across an optical buffer layer 11 and a grating 16 formed on the surface of this optical waveguide 15 optically couples the optical waveguide 15 with the outside. In this case, the grating 16 propagates diffracted light of high-order mode to the optical waveguide layer 15. |
