Optical fiber span with low differential mode delay

Abstract

A fiber span comprising: a first optical fiber and a second optical fiber coupled to the first optical fiber, both fibers comprising the an inner core region with maximum refractive index delta, Δ≦0.1% and an outer radius R>4.5 μm, an outer core region with an outer radius Rand a minimum refractive index delta Δand alpha value α≧5, wherein Δ<Δ, 5.5 μm≦R−R≦12 μm; a cladding including a low index ring surrounding the core and a minimum refractive index delta Δ<Δ; and an outer cladding having Δ>Δ; the first fiber introducing differential mode delay DMDfor wavelengths between 1525 and 1570 nm such that |DMD|≦100 ps/km, and a first differential mode delay slope DMDS; the second fiber introducing differential mode delay DMDfor wavelengths between 1525 and 1570 nm such that |DMD|≦100 ps/km, and a second differential mode delay slope DMDSthat has an opposite sign from the first dispersion slope DMDS; wherein total differential mode delay provided by the first fiber in conjunction with the second fiber is DMD=DMD+DMD, and −1.0 ps/km<DMD<1.0 for all wavelengths between 1525 nm and 1570 nm.