| 摘要 |
PURPOSE: To provide a rare earth element added multicore optical fiber preform high in refractive index and improved in amplification property and the producing method. CONSTITUTION: The rare earth element added multicore optical fiber preform is obtained by covering the outer periphery of plural cores 2 high in refractive index, which uses quartz as a main raw material and in which the rare earth element and Ge are doped, with a 1st clad 3 low in refractive index, which uses quartz as a main raw material and in which F is doped, and arranging a 2nd clad 8 composed of a pure quartz on the outer periphery thereof. The producing method is carried out by charging the plural core members 2 and the 1st clad member 3 into a pure quartz tube and collapsing the members 2, 3 and the quartz tube by heating with a burner to vitrify and integrate. |
