Optical fiber preform, production method thereof, and optical fiber produced from the preform

摘要

An optical fiber preform having a low core noncircularity and eccentricity for producing an optical fiber having an improved polarization mode dispersion, a method for producing the preform, and an optical fiber produced from the preform. The optical fiber preform is produced by the following steps. Diameter-reduced portions 11a and 11b are formed in the vicinity of the ends of the glass pipe 11. A glass rod 12 is inserted into the glass pipe 11. The glass rod 12 is fixed to the glass pipe 11 at the diameter-reduced portion 11a. The glass pipe 11 and the glass rod 12 are heat-unified from the diameter-reduced portion 11b forward to the diameter-reduced portion 11a. The optical fiber preform has a core noncircularity of at most 1.5%. The optical fiber has a polarization mode dispersion of at most 0.15 ps/km1/2 at a wavelength of 1,550 nm.