Patent ID: 7194171

Claim:
A dispersion compensating optical fiber comprising: a core; and a cladding surrounding said core; wherein: said core and said cladding are arranged so as to obtain negative dispersion at 1550 nm; and when said dispersion compensating optical fiber is employed in an optical transmission system and a particular use wavelength band is used as a signal wavelength band, said dispersion compensating optical fiber exhibits such loss characteristic that a minimum wavelength at which a difference between an actual loss value α 1 (λ) and a theoretical loss value α 0 (λ) is not less than 10 mdB/km in the use wavelength band and on a long wavelength side of the use wavelength band falls within a range of 1,565 to 1,700 nm, wherein said actual loss value α 1 (λ) is measured in a state that the fiber is looped around a bobbin, and wherein the theoretical loss value α 0 (λ) of the fiber is obtained by the following equation, α 0 (λ)= A/λ 4 +B+ 6.65×10 12 ·exp (−52.67/λ) where λ [unit: μm] is a wavelength of an optical signal, A is the Rayleigh scattering coefficient, and B is a constant representing a loss due to structure mismatching.