| 摘要 |
PROBLEM TO BE SOLVED: To provide a single-mode optical fiber in which faulty part in transmission loss can be easily specified through OTDR measurement from only one end of an optical fiber, and also to provide a preform for producing such optical fiber as well as its evaluation method. SOLUTION: The preform for a single-mode optical fiber is constituted of a columnar core and a cylindrical clad surrounding the core. The preform is characterized by having a variation of 6% or below as to the specific index differenceΔn in the longitudinal direction, assuming the index of refraction is n1 and n2 for the core and the clad respectively. |
