Optical waveguide element and method of manufacturing the same
An object of the present invention is to provide a manufacturing method of an optical waveguide element whose DC drift is suppressed, and to provide a manufacturing method of an optical waveguide element, capable of adjusting DC drift in the middle of manufacturing processes so as to improve a fabrication yield. The method of manufacturing an optical waveguide element comprises a step of forming an optical waveguide in a substrate having an electro-optic effect, a step of forming a buffer layer, and a step of forming an electrode, in which one stage or a plurality of stages of an interface diffusion layer heat adjustment step (S 1 , S 2 ) for adjusting a concentration distribution of a specific substance in the buffer layer by heating is included after the buffer layer is formed.
1. An optical waveguide element comprising:
a substrate having an electro-optic effect;
an optical waveguide formed in the substrate;
a buffer layer formed on the optical waveguide and made mainly from SiO 2 ; and
a modulation electrode formed on the buffer layer and modulating light waves which propagate through the optical waveguide,
wherein the buffer layer has a region which contains Li of 1×10 21 (atoms/cm 3 ) or more at a substrate side of the buffer layer, and
a thickness of the region which contains Li of 1×10 21 (atoms/cm 3 ) or more in the buffer layer is a quarter or more of a thickness of the buffer layer.
2. The optical waveguide element according to claim 1 , wherein the buffer layer is doped with at least one of In and Ti.