Passive equalization of four 2.5-Gbit/s WDM channels over 1,000 km using notch filters

Summary form only given. In this work, we experimentally demonstrate passive equalization of the nonuniform gain of cascaded Er-doped fiber amplifers (EDFAs) for which a newly-generated gain peak appears near 1560 nm. The passive equalization is accomplished over a 7.4-nm wavelength range by periodically using notch filters along a 1000-km transmission link. Our results show that the signal power differential among the four WDM channels is reduced from 19 dB to 4 dB and that the 10/sup -9/ BER receiver sensitivity differential among the channels is decreased from 7.5 dB to only 3 dB.