| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical fiber including an alkaline metal element and capable of reducing Rayleigh scattering loss.SOLUTION: An optical fiber 1 includes a core 11 composed of silica glass and a clad 12 surrounding the core, having a refractive index lower than a refractive index of the core and composed of silica glass containing fluorine. Further, the core 11 includes a first dopant group composed of any one of Na, K and a compound of the elements at an average concentration of 0.2 ppm or more and a second dopant group which is dopant for reducing viscosity of silica glass and of which the diffusion coefficient at any one temperature of temperatures of 2000 to 2300°C is 1×10cm/s or more and smaller than a diffusion coefficient of the first dopant group at an average concentration of 0.2 ppm or more.SELECTED DRAWING: Figure 1 |
