METHOD OF MEASURING DISTRIBUTION OF BENT LOSS IN LONGITUDINAL DIRECTION OF OPTICAL FIBER AND OPTICAL FIBER LINE, METHOD OF TESTING OPTICAL LINE, AND METHOD OF MANUFACTURING OPTICAL FIBER

摘要

PROBLEM TO BE SOLVED: To measure the distribution of bent loss in the longitudinal direction of an optical fiber by a bidirectional OTDR measuring method.SOLUTION: In the method for measuring the distribution of bent loss in the longitudinal direction of the optical fiber, an arithmetic mean value I(x) is calculated from two back-scattered light intensity values, on a position x, of two back-scattered light beams obtained by bidirectional OTDR measurement of the optical fiber, and a bent loss value is obtained from a mode field diameter 2W(x) and a relative refractive index difference (x) on the position x, which are calculated from the arithmetic mean value I(x). When obtaining the bent loss value, it is preferable that the target optical fiber is regarded as an optical fiber having step type refractive index distribution equivalent to the refractive index distribution of the target optical fiber and the bent loss value on the position x is calculated from a relational expression of a standardized frequency V of the optical fiber having the step type refractive index distribution, a core radius (a) and a node field diameter 2W.