| 摘要 |
PURPOSE:To prevent axial shift of a linearly polarized wave and deterioration of degree of polarization, by providing a hollow part in a clad except for a stress applying part. CONSTITUTION:A core 1 consists of glass whose refractive index is higher than that of glass for clad, and a stress applying part 3a and 3b consist of glass whose refractive index is lower than that of the glass for clad and also, whose coefficient of thermal expansion is high. The applying parts 3a, 3b and hollow parts 4a, 4b are in an axial symmetry position centering around the core 1, and also, an axis for connecting the center of the applying parts 3a, 3b and the core 1 and an axis for connecting the center of the hollow parts 4a, 4b and the core 1 are provided in positions being orthogonal to each other. In this state, due to existence of the hollow part 4a and 4b, a difference is generated in the moment required for bending, depending on the direction for bending the fiber. Accordingly, by bending easiness of the fiber, an axis of a fiber section can be decided, and also, the fiber which has been started to be wound in the easily bendable direction once generates no axial shift (variation in the winding direction). |
