| 摘要 |
PURPOSE: To provide a production method of an optical fiber preform uniformalized in a refractive index distribution in a side core. CONSTITUTION: A burner for composing the side core part 3 of a porous preform 1 is made in a square multiple pipe structure, and a gaseous starting material charging layer disposed at a center of its blow-off port is made in a rectangle having a major axis in a direction along a deposition axis, and this gaseous starting material charging layer is divided into plural layers in the major axis direction, and a gaseous starting material of glass is charged from each of divided layers 33, 34 and 35, and also, dopant gas is added to the gaseous starting material at more than two divided layers and gaseous hydrogen is added to the gaseous starting material at more than one divided layers. |
