Optical fiber and optical transmission path

摘要

Under condition that a non-circularity ratio is 5% or lower and a thermal expansion coefficient of a glass which forms the core is α1 and a thermal expansion of a glass which forms the cladding is α2, the difference of coefficients is controlled such that a formula -2.5×10-7/°C ≤ α1-α2 ≤ 1.0×10-7/°C is satisfied so as to maintain a polarization mode dispersion to be 0.03 ps/km0.5 or lower. The difference of coefficients is further controlled such that a formula -1.5×10-7/°C≤ α1-α2 ≤ 0/°C is satisfied so as to maintain a polarization mode dispersion to be 0.015 ps/km0.5 or lower. By doing this, birefringence is reduced by adjusting the thermal expansion coefficient in a core and a cladding; thus providing an optical fiber, and an optical transmission path using the optical fiber, having preferable PMD for high speed transmission.