An optical fiber transmission link has a first optical fiber with a high effective
area coupled to a second, downstream optical fiber with a low effective area. The
downstream fiber has non-zero dispersion and low dispersion slope. Characteristics
of the upstream fiber permit the launching of high power channels in a wavelength
division multiplexing, and characteristics of the downstream fiber enable Raman
amplification along that fiber to extend the transmission distance before a need
for discrete amplification. The downstream fiber has a non-zero dispersion in the
C-band wavelengths and a low dispersion slope and has low attenuation at the signal
and pump wavelengths. Refractive-index profiles include variations of W-type fibers
that may include outer rings of positive or negative index. Pumping of the downstream
fiber may occur either co-directionally to the signals, counter-directionally to
the signals, or in both directions.