| 摘要 |
PURPOSE:To form a core layer and a clad layer at the same time, in the production of a preform by VAD process, by using a single concentric multiple-tube burner, mixing the glass raw material uniformly with a doping agent, and keeping the distance between the burner nozzle and the deposition surface to a specific level. CONSTITUTION:A uniform mixture of a glass raw material and a doping agent is ejected from the center nozzle of a multiple-tube burner into an oxy-hydrogen flame formed by the multiple-tube burner. The glass soot formed by the flame hydrolysis is blasted toward the tip of the rotating target while keeping the distance between the nozzle of the burner and the deposition surface to >=50mm.. The glass soot is deposited and grown along the axial direction. The core soot layer containing the doping agent and the clad soot is deposited and grown along the axial direction. The core soot layer containing the doping agent and the clad soot layer free from the doping agent can be formed at the same time by this process. The product is fused and made transparent to obtain a glass preform for an optical fiber free from refractive index irregularity and having transmission loss. |
