| 摘要 |
Provided is an optical fiber base material having a trench type refraction index distribution shape with small structure denial. The present invention relates to a silica glass base material for optical fiber, comprising a core, an interlayer, a trench layer, and a clade layer. The core adds positive dopant which increases a refraction index to silica glass. The interlayer is adjacent to the outside of the radial direction of the core to surround the core. The trench layer is adjacent to the outside of the radial direction of the interlayer to surround the interlayer and adds negative dopant which decreases the refraction index to the silica glass. The clade layer is adjacent to the outside of the radial direction of the trench layer to surround the trench layer and is formed with the silica glass. The thickness of the radial direction of the interlayer is larger than the thickness of the trench layer. The positive dopant is added to an area which is close to the core of the interlayer. The negative dopant is added to an area which is close to the trench layer. |
