| 摘要 |
PURPOSE:To decrease warpage of a Si substrate to be extremely small after a first clad layer is formed. CONSTITUTION:First, a groove 7 having width W2 and height H necessary to satisfy the optical characteristics to embed a first clad layer is formed in a Si substrate 1, and the first clad layer 2 comprising SiO2 glass having refractive index n0 is embedded in the groove 7. Then, the whole surface of the Si substrate including the first clad layer 2 is coated with a core glass film 3 having refractive index n1 (n1>n0). Then, a core waveguide 4 having an almost square cross section is formed by photolithography and reactive ion etching on the first clad layer 2. Further, a porous glass layer 5 of SiO2-B2O3-P2O5 is formed by flame deposition method on the whole surface of the Si substrate 2 including the core waveguide 4. The glass layer is sintered to the changed into a transparent glass to form a SiO2-B2O3-P2O5 glass having n0 refractive index as the second clad layer 6. |
