| 摘要 |
PURPOSE:To facilitate manufacture, and to reduce loss and couple convergent type optical fibers with high efficiency by mixing gaseous raw material which forms a core layer and a gaseous raw material which forms a clad layer, and forming the core layer while varying their mixing ratio gradually. CONSTITUTION:A gaseous raw material and O2 are admitted into a diffusion furnace 10 and oxidation is carried out to deposit particulates of the 1st clad layer 2 on a quartz glass substrate 1 in a deposition area 30. Then, the gaseous raw material filling the diffusion furnace 1 is not purged, and a gaseous raw material for forming a core layer 3 is admitted. The gaseous raw materials are mixed and the ratio of the gaseous raw material for the core layer 3 increases gradually to deposit particulates of the core layer 3. Then, a gaseous raw material is admitted on the same condition with the formation of the 1st clad layer 2 without purging said gaseous raw material gas. The gaseous raw materials are mixed again and the ratio of the gaseous raw material for the 2nd clad layer 4. Annealing is performed in an electric furnace to obtain transparent glass. |
