| 摘要 |
PURPOSE:To reduce the insertion loss of an optical waveguide, and also, to decrease the dispersion of the insertion loss by forming a high refractive index layer in a substrate material by a proton exchange method, and then subjecting the layer to anneal treatment. CONSTITUTION:A material to be treated, containing a substrate material consisting of a electro-optic crystal is subjected to proton exchange treatment at 190-200 deg.C for 10-40 minutes, and subsequently, subjected to anneal treatment under the condition showing in the following inequality. (-1/20)T+21.5<=(t)<=(-4/25)T+64.4, 320<=T<=380 (where, (t) (time), and T( deg.C) denote an anneal treatment time, and an anneal treatment temperature, respectively). |
