| 摘要 |
PURPOSE:To easily manufacture the titled fiber by utilizing an external method and a VAD method being suitable for a mass production, by containing simultaneously a dopant and fluorine for raising a refractive index of quartz glass, in at least one area among areas except a core. CONSTITUTION:A core 50 is formed by only adding germanium. The addition quantity of fluorine is the same with respect to both a first clad layer 10 and a second clad layer 20 in the case of figures 1a, 1b, and also, the same extending from the first clad layer 10 to a third clad layer 30 in the case of figures 1c, 1d. Only the addition quantity of germanium is varied at every clad layer, and a refractive index distribution as shown in the upper stage of each figure is formed. In such a way, since the refractive index distribution which is varied up and down complicatedly in the diameter direction, the deterioration of a transmission characteristic is not caused, and by utilizing an external method and a VAD method, said fiber can be manufactured easily. |
