Silica based optical waveguide and production method therefor

摘要

A silica based optical waveguide is described, comprising a substrate, a core waveguide formed thereon, and an over cladding part comprising a silica based glass with a refractive index lowering dopant and a refractive index increasing dopant added, formed on the substrate so as to cover the core waveguide, wherein a segregation layer with a higher concentration of the refractive index increasing dopant is formed in a part of the over cladding part in contact with the substrate and the core waveguide such that at least a part of the refractive index increase in the segregation layer provided by the refractive index increasing dopant with respect to the part of the over cladding part other than the segregation layer is offset by decline of the refractive index by increasing the amount of the refractive index lowering dopant added in the segregation layer and/or adding another refractive index lowering dopant.