| 摘要 |
PURPOSE:To eliminate a structural defect such as oxygen defect and to decrease transmission loss by consisting a base material of the 1st core center layer consisting of high-purity quartz glass, the 2nd core layer contg. fluorine at a low concn. and exhibiting the refractive index lower than the refractive index of the 1st core center layer and a clad layer contg. the fluorine at a high concn. and exhibiting the refractive index lower than the refractive index of the 2nd core layer. CONSTITUTION:The base material is constituted by forming the core layer into two layers, forming the clad layer thereon and doping the fluorine at different concns. to both of the outside layer of the core part and the clad layer. A burner 3 for flame hydrolysis is moved laterally to deposit soot 2 for core on a quartz glass rod 1 while said rod is rotated. Soot 4 for forming the clad layer is deposited on the soot 2 in order to form the clad layer after the prescribed quantity of the soot for the core is deposited. The glass raw material compd. for the purpose of depositing the soot 4 for the clad is required to be of the compsn. having the refractive index lower than the refractive index of the core layer and therefore said compd. needs to be of the kind or compsn. with which the doping quantity of the fluorine increases. |
