Patent ID: 7333679

Claim:
A thermo-optic phase shifter comprising: a substrate; a heater; a clad layer provided directly or indirectly on said substrate; a bridge section clad layer formed apart from said substrate and said clad layer in a portion corresponding to said heater; and a core layer provided inside said bridge section clad layer, wherein said bridge section clad layer and said core layer form a bridge section optical waveguide in said heater corresponding portion, and said heater is provided inside or outside said bridge section optical waveguide apart from said core layer in said heater corresponding portion, and generates heat to change a phase of a light signal propagated in said bridge section optical waveguide, said clad layer is formed on said substrate through a sacrifice layer, said sacrifice layer is formed of material with an etching rate larger than that of said substrate, and said sacrifice layer is formed of the material with a thermal conductivity smaller than that of said substrate, wherein said sacrifice layer is formed of glass doped with phosphorus, and said clad layer is formed of glass doped with boron and phosphorus.