| 摘要 |
PURPOSE: To dispense with the increase of sintering temperature, and reduce bubbles without deforming a glass waveguide by changing the pressure in a sintering furnace, when a porous glass is sintered to form clad glass. CONSTITUTION: A core glass doped With titanium is formed on a quartz glass 3 by electron beam evaporation. A core waveguide 1 is successively formed by photolithography and etching. A porous glass is formed on the quartz glass base 3 having the core waveguide 1 formed thereon by frame accumulation. Thereafter, the porous glass is sintered to form a glad glass 2. At the sintering of the clad glass 2, deaeration is performed by changing the pressure in a sintering furnace. Namely, bubbles are removed at glass fusion by pressure reduction, and the bubbles are extinguished by pressurization. The change of the pressure is preferably set 3 times or more. Thus, the bubbles in the clad glass 2 are eliminated. |
