Terminal-only compensation of a 6 x 80 km 10-gb/s WDM metro link using Raman-pumped dispersion-compensating fiber amplifiers

We investigate the use of dispersion-compensating Raman amplifiers (DCRAs) designed for terminal-only dispersion compensation of a typical 6 x 80 km 10-Gb/s wavelength-division-multiplexing metro link over standard single-mode fiber. The one-stage booster and two-stage preamplifier DCRAs were comprised of high figure-of-merit (400 ps/nm/dB) dispersion-compensating fiber. After transmission, all channels had less than 2.2-dB optical signal-to-noise ratio (OSNR) penalty (at 10(-9) bit-error ratio) and more than 7-dB OSNR margin. Further measurements showed that the penalty could be attributed to the large accumulated dispersion during transmission due to the terminal-only compensation, and not to nonlinearities; or multiple path interference in the DCRAs.