OPTICAL WAVEGUIDE, OPTICAL MODULE AND OPTICAL SYSTEM USING THE SAME

摘要

An optical waveguide comprises an anhydrous synthetic silica glass substrate which contains less than a predetermined concentration of hydroxyl group, a core waveguide having a rectangular cross-section being formed on the substrate, and a cladding layer having a lower refractive index than the core waveguide and which covers the core waveguide . The concentration of hydroxyl group contained in the synthetic silica glass substrate of the optical waveguide or the optical device is essentially less than 300 ppm, preferably less than 100 ppm, more preferably less than 50 ppm.