| 摘要 |
An optical fiber having a sufficiently large effective cross sectional area while suppressing an increase of the dispersion slope in the 1.55 mu m wavelength band. The optical fiber comprises an inner core where a core region extends along a predetermined axis and an outer core provided on the periphery of the inner core and having a refractive index lower than that of the inner core. Specifically, the relative index difference DELTA n1 of the inner core to the reference region in the clad region provided on the periphery of the core region, the relative index difference DELTA n2 of the outer core to the reference region, the ratio a/b of the outside diameter (2b) of the outer core to the outside diameter (2a) of the inner core, outside, and the outside diameter (2b) of the outer core are all adequately determined according to the structure of the clad region. |
