RIDGE TYPE OPTICAL WAVEGUIDE

摘要

PURPOSE:To increase light confinement at the right and left sides of a ridge type optical waveguide and to reduce transmission loss by laminating an optical thin film whose refractive index is equal to or smaller than that of a substrate and smaller than that of a ridge type optical waveguide on the ridge of the ridge type optical waveguide. CONSTITUTION:The optical waveguide layer 2 which has a little bit larger refractive index than the optical substrate is formed on the optical substrate 1 and then worked in a ridge shape to form the ridge type optical waveguide 3. Further, the optical thin film 4 whose refractive index is equal to or larger than that of the substrate and smaller than that of the optical waveguide is formed on the ridge. Consequently, the equivalent refractive index of the ridge part 3 becomes larger and the difference in the refractive index from the periphery of the ridge also increases.