JPS57173820A - Optical switch - Google Patents

Abstract

PURPOSE:To obtain a thin and small-sized optical switch which is small in its propagation loss and is used for an optical IC, etc., by covering the surface of a substrate with a protective film, providing grooves meeting at right angles with each other, on the film, forming an optical waveguide in the grooves, providing a buffer layer on the crossing part of the optical waveguide, and also providing comb line electrode on said layer. CONSTITUTION:On a substrate 22 of a sapphire, etc., a film 231 of SiO2, etc. is formed, U-grooves meeting at right angles with each other are formed on the film 231, and an optical propagation medium 233 whose refractive index is larger than that of a substrate surface 221 and the film 231 is embedded in the grooves, by which an optical waveguide is formed. Subsequently, on a crossing part 24 of the waveguide 23, a buffer layer 25 is formed by use of SiO2, etc. After that, a pair of comb line electrodes 26 are formed by an Al film, etc. at an electrode interval satisfying the Bragg's condition. In this way, when a suitable electric field is applied to the electrodes 26, the refractive index of the medium 233 is varied, it does not travel straight but is propagated to other optical waveguide. It is possible to easily obtain a small-sized and thin optical switch 21 whose propagation loss is small.