OPTICAL WAVEGUIDE AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To prevent the increase in transmission loss by precipitation of crystals in a glass film in forming a core layer. SOLUTION: Channel waveguides 3a are formed on a quartz substrate 1 and the surface thereof is covered with a clad glass layer 4. The respective channel waveguides 3a have upper and lower two-layered structures. The lower core glass layer 2 have 0.1 to 2μm thickness and contains at least >=2 kinds of additives among the respective additives of germanium, boron, phosphorus and titanium. The total content of the respective additives added thereto is regulated within a range of 13 to 20wt.%.