| 摘要 |
PURPOSE:To obtain the title fiber having an excellent transmission characteristic in good yield by externally depositing the fine glass particles contg. B and P on the outer periphery of the core rod consisting of a Ge-contg. core and a silica clad, sintering the material, and then drawing the sintered material. CONSTITUTION:The core rod 3 consisting of a Ge-doped core 1 and a silica clad 2 is ground into the shape having an elliptic cross section. The fine glass particles contg. B and P is then externally deposited on the outer periphery of the worked core rod 3 by a VAD method. At this time, the deposition is carried out so that the outer diameter after sintering is controlled to about 50mm. In addition, the molar concn. of B is controlled to about 8mol.%, the concn. of P is set so that the refractive index of the deposited part is controlled to the same value as that of silica, and doping is carried out. The core rod 3 thus externally deposited is sintered, and a fiber base material wherein a supporting layer 4 is formed on the outer periphery of the clad 2. The fiber base material is drawn to produce a polarization plane maintaining optical fiber. |
