| 摘要 |
PURPOSE:To presicely controll the sectional form and dimensions of a core layer, etc. by successively lowering the softening temp. of glass for lower clad, core and upper clad layers to be laminated on a substrate in order. CONSTITUTION:On substrate 1 made of quartz glass GeO2-SiO2 glass layer 2 is deposited in a predetermined thickness, and the unnecessary part of layer 2 is removed by etching in accordance with a desired pattern. On layer 2, P2O5-B2O3- SiO2 glass layer 3 is then deposited in a predetermined thickness. The softening temp. of the P2O5-B2O3-SiO2 glass can be controlled without changing the refractive index by making the P2O5 and B2O3 contents about equal and changing the total amount of P2O5 and B2O3. Accordingly, the composition of upper coating glass having a lower softening temp. can be determined correspondingly to the composition of the core. |
