Patent ID: 7263267

Claim:
A higher order mode dispersion compensating fiber, comprising: an optical fiber; and a loss layer which is provided within the fiber and which attenuates a lower order mode propagating through the optical fiber while not attenuating a higher order mode which is higher than the lower order mode, wherein the loss layer comprises glass doped with at least one element selected from the group consisting of cobalt, chromium, copper, iron, nickel, manganese, boron, and vanadium, and a position of the loss layer is determined as follows: P m ⁡ ( r ) = A ⁢ ⁢ exp ⁡ [ - ( r - r 0 δ ) 2 ] + B where P m (r) is a material loss in the fiber profile, r is a radial distance from the center, A is a peak attenuation in the loss layer (dB/km), B is a loss in the other layers (dB/km), r 0 is a radial distance of the middle point between the top and the bottom of the loss layer from the center, δ is 2 √{square root over (2)} Δr, and Δr is a full width at half maximum of a loss in the loss layer.