Patent ID: 6867905

Claim:
In an optical communication system, apparatus for amplifying an optical signal, said apparatus comprising: a fiber; and an optical pump energy source disposed to inject optical pump energy into said fiber in a co-propagating direction relative to a transmission direction of an optical signal in said fiber to cause Raman amplification of said signal in accordance with a gain level; and wherein said gain level is greater than 4 dB; and wherein either 1) for a selected signal to noise ratio, there is a greater four-wave mixing product suppression level than would be achieved using only a counter-propagating optical pump energy source to obtain said gain level or 2) for a selected four-wave mixing product suppression level, there is a higher signal to noise ratio than would be achieved using only said counter; propagating energy source to obtain said gain level; and wherein said gain level is set responsive to a minimum tolerable four-wave mixing product suppression level and a desired signal to noise ratio.