Tapered optical waveguide, waveguide type optical head using same and optical waveguide

摘要

A tapered optical waveguide is disclosed, which comprises a substrate having a plane surface for forming a waveguide layer, whose refractive index is higher than that of the substrate, which substrate is transparent with respect to guided light, and a waveguide layer formed on the plane surface of the substrate, in which light taken out on the substrate side is focused so as to form a small spot at a position distant from the interface between the waveguide layer and the substrate.