A METHOD FOR FABRICATING AN OPTICAL WAVEGUIDE

摘要

In the first step, a fuel and raw material gasses are fed to a burner (4) while flames from the burner scan a Si substrate (1). Synthesized glass fine particles are deposited on the substrate (1) to form a first porous vitreous layer (5) to be a under cladding layer. In the second step, the first porous vitreous layer (5) is heated by the flames. A bulk density of an upper part of the first porous vitreous layer (5) is raised to 0.3 g/cm<3>. This upper part with a raised bulk density functions as a shield layer against GeO2. In the third step, a second porous vitreous layer (6) to be a core layer is deposited uniformly on the first porous vitreous layer (5). In the fourth step the first and the second porous vitreous layers (5, 6) are sintered. In this case, the shield layer with a higher bulk density hinders the GeO2 component which has evaporated from the second porous vitreous layer (6) from diffusing into the first porous vitreous layer (5).