Researchers from SDL Inc. of San Jose, Calif., and AT&T Labs-Research of Red Bank, N.J., have reported that their field tests show that distributed Raman amplification improves the performance of 10-Gb/s wavelength division multiplex transmission. They used 40 km of installed older-vintage fiber to demonstrate that SDL's RL30 Raman pump modules can be incorporated into existing terrestrial networks without damaging the fiber or connectors.

The researchers estimate that, at optimum pump power levels of 650 mW, the 17-dB average channel Q-value would enable transmission over up to seven 120-km spans, rather than three with-out Raman amplification. Pump powers of up to 950 mW did not damage the fiber.