| 摘要 |
PURPOSE:To easily control the elliptical shape of a clad by forming the above optical fiber of the 4-layered structure consisting of a core, clad, stress imparting layer, and jacket layer and forming the clad to the approximately elliptical shape in section. CONSTITUTION:The optical fiber is formed of the 4-layered structure consisting of the core 1, the clad 2, the stress imparting layer 3, and the jacket layer 4 and the clad 2 is made into the approximately elliptical shape in section. The fine particles of glass contg. B and P are externally deposited by a VAD method on the outer peripheral part of the core rod formed by working the clad 2 to the elliptical shape. Further, the externally deposited core rod is sintered to obtain the base material formed with the stress imparting layer 3 on the outer peripheral part of the clad 2. This base material is fixed into a performed glass tube consisting of the same material as the material of the clad 2 to obtain the base material for the fiber. This base material for the fiber is drawn to obtain the polarization plane maintaining optical fiber. The easy control of the elliptical shape of the clad 2 is possible in this way and the polarization plane maintaining optical fiber having improved crosstalk characteristics and excellent transmission characteristics is obtd. The impartation of desired double refractiveness to the core is possible. |
