| 摘要 |
PURPOSE:To decrease the fluctuation in fiber diameter by specifying the refractive indices of the core, inside clad, outside clad and stress imparting parts and forming the stress imparting parts so as to have the coefft. of thermal expansion larger than the coefft. of thermal expansion of the inside clad and the outside clad. CONSTITUTION:The core 1, the inside clad 5 which encloses the core and has the diameter of <=10 times the diameter of the clad, the outside clad 6 which encloses the inside clad 5 and 2 pieces of the stress imparting parts 7 which are provided in the position symmetrical with the center of the core 1 between the outside diameter of the core 1 and the outside diameter of the outside clad 6 and have the refractive index lower than the refractive index of the outside clad 6 are provided. The refractive index of the core 1, designated as nc, the refractive index of the inside clad 5, as n1, the refractive index of the outside clad 6, as n2, and the refractive index of the stress imparting parts, as n3, are specified to nc>n1, nc>n2, and n3>n2. The coefft. of thermal expansion of the stress imparting parts 7 is so determined as to be larger than the coefft. of thermal expansion of the inside clad 5 and the outside clad 6. The absolute single polarization optical fiber which decreases the fluctuation in the fiber diameter and has the low loss, low crosstalks and a wide band is thereby obtd. as desired with good reproducibility. |
