Patent ID: 6644870
Filing Date: 2003-11-11
Classification: G02B

Abstract:
An optical fiber transmission line comprising:a first optical fiber having a core region doped with a 10 mol % or more of Ge and the Peterman II mode field diameter with a first minimum value of 7 &mgr;m or less at a wavelength of 1550 nm; and a second optical fiber having one end fusion-spliced to that of said first optical fiber, said second optical fiber having a core region doped with 10 mol % or more of Ge and the Peterman II mode field diameter with a second minimum value of 7 &mgr;m or less at the wavelength of 1550 nm, a difference between the first and second minimum values being 1 &mgr;m or less; wherein the Peterman II mode field diameter of said first optical fiber, at a position separated by at least 2 mm from a fusion-spliced position between said first and second optical fibers, is enlarged so as to reach a value of 110% or more of the first minimum value, and the Peterman II mode field diameter of said second optical fiber, at a position separated by at least 2 mm from said fusion-spliced position between said first and second optical fibers, is enlarged so as to reach a value of 110% or more of the second minimum value.