HYBRID EDFA CHARACTERIZATION FOR WDM TRANSMISSION WITH VARIOUS SPAN LOSS

A hybrid Er3+-doped fiber amplifier (EDFA) combining Al co-doped and P -Al co-doped Er3+-doped fiber (EDF) has been developed for terrestrial WDM repeater systems to minimize gain variations at an arbitrary span gain. The relations among the span loss, output variation, and accumu lated ASE noise in WDM transmission systems are investigated using the hybrid EDFA. It is found that for a design span gain of 25 dB of the hybrid EDFA, an output variation of 1.6 dB (0.3 dB/stage) is obtained after five-stage amplification, and when an output variation of 5 dB ( 1 dB/stage) is allowable, the allowable span loss variation more than +/- 3 dB of the designed value. A maximum total loss margin of about 1 80 dB (BER = 10(-10)) is obtained in a 2.5G bps x 4 channel WDM transm ission experiment using five-stage hybrid EDFAs and 509 km of single-m ode fibers (SMF). (C) 1997 Scripta Technica Inc.