| 摘要 |
PROBLEM TO BE SOLVED: To obtain optical waveguide gratings of a substrate type having good production efficiency at a low cost by using a substrate type optical waveguide provided with a high germanium layer between a silicon substrate and a clad layer. SOLUTION: This substrate type optical waveguide is constituted by providing the surface of the substrate 11 with the high germanium layer 12, providing the surface of the layer with the clad layer 13 and providing the inside of the clad layer 13 with a core 14. Namely, the constitute obtd. by forming the clad layer 13 around the core 14 is adopted. The substrate 11 is a planar, for which the silicon substrate is adequately used. The high germanium layer 12 consists of SiO2 added with germanium oxide. The absorption effect of UV light is determined by the layer thickness of the high germainium layer 12 and the amt. of the germanium oxide to be added. In such a case, more than the needed increase of the thickness of the substrate type waveguide is undesirable and, therefore, the smaller thickness of the high germanium layer 12 is more preferable. |
