Measuring method of longitudinal distribution of bending loss of optical fiber, measuring method of longitudinal distribution of actual bending loss value of optical fiber, test method of optical line, manufacturing method of optical fiber cable, manufacturing method of optical fiber cord, and manufacturing method of optical fiber

摘要

A measuring method of a longitudinal distribution of bending loss of an optical fiber includes calculating an arithmetical mean value I(x) from two backscattering light intensities of two backscattering light at a position x obtained by bidirectional OTDR measurement of the optical fiber; and obtaining a bending loss value at the position x from a mode field diameter 2W(x) and a relative refractive index difference Δ(x) at the position x calculated from the arithmetical mean value.

主权项

1. A measuring method of a longitudinal distribution of bending loss of an optical fiber, the method comprising:
conducting a bidirectional OTDR measurement of the optical fiber in a longitudinal direction of the optical fiber; calculating an arithmetical mean value I(λ, x) from two backscattering light intensities of two backscattering lights at a position x obtained by the bidirectional OTDR measurement of the optical fiber; obtaining a mode field diameter 2W(λ, x) and a relative refractive index difference Δ(x) between a core and a clad of the optical fiber at the position x and a wavelength λ, using the arithmetical mean value I(λ, x), formula (2), formula (3), and formula (4):k=10·log⁡[{1+0.62⁢Δ⁡(x)1+0.62⁢Δ⁡(x0)}⁢{50-Δ⁡(x)50-Δ⁡(x0)}](2)2⁢W⁡(λ,x)=2⁢W⁡(λ,x0)·[2⁢W⁡(λ,x1)2⁢W⁡(λ,x0)]I⁡(λ,x)-I⁡(λ,x0)I⁡(λ,x1)-I⁡(λ,x0)(3)andΔ⁡(x)=1k[{1+k⁢⁢Δ⁡(x0)}·10I⁡(λ,x)-20⁢⁢log⁢{2⁢W⁡(λ,x0)2⁢W⁡(λ,x)}10-1](4) obtaining a bending loss value at the position x based on the mode field diameter 2W(λ, x) and the relative refractive index difference Δ(x) at the position x.