| 摘要 |
PURPOSE:To inhibit the generation of unnecessary mode other than transmission mode in the cores of an optical fiber by specifying the difference in refractive index between the stress applying parts and the jacket and the difference in refractive index between the stress applying parts and the clads. CONSTITUTION:A single-polarization optical fiber is composed of cores, clads having a lower refractive index than the cores, stress applying parts for applying axially asymmetric stress to the cores, and a jacket surrounding them, and the difference in refractive index between the stress applying parts and the jacket and the difference in refractive index between the stress applying parts and the clads are specified to <=0.05%. In order to control unnecessary mode of the optical fiber, dopants in the stress applying parts are regulated as folllows. (1) When Ge and B are used, the mol% of B2O3 is made 4.0-4.1 times the mol% of GeO2. (2) When P and B are used, the mol% of B2O3 is made 2.0-2.1 times the mol% of P2O5. (3) When Ge and F are used, the mol% of GeO2 is made 3.5-3.6 times the mol% of F. |
