| 摘要 |
In the optical fiber, the concentration of fluorine doped in the core portion (2) is made nonuniform in the radial direction to be greater at the center portion of the core portion (2) and less at the outer circumferential portion of the core portion (2). As a result, the distribution of the refractive index of the core portion (2) and the cladding portion (4) before the process of transparent glassification becomes a profile which is high at the outer circumferential portion of the core portion (2) and which is low at the center portion. The reduction of the refractive index at the outer circumferential portion of the core portion (2) due to the dispersion of the GeO2 etc., the oxide included in the core portion (2), in the cladding portion (4) in the transparent glassification processed is and as a result, the profile of the refractive index of the core portion (2) becomes one which sticks out in a step form with respect to the cladding portion (4). <IMAGE> |
