Experimental demonstration of dynamic network equalization of three 2.5-Gb/s WDM channels over 1000 km using acoustooptic tunable filters

Abstract
We have experimentally demonstrated the dynamic equalization of the nonuniform EDFA gain and WDM-network channel-power variations by using acoustooptic tunable filters (AOTF's) with active feedback. The AOTF's have multiple independent passbands and act as dynamic wavelength-dependent loss elements. After 1000 km transmission in a recirculating loop, the power differential is reduced from 20 dB to 1 dB for three 2.5-Gb/s WDM channels covering an 8-nm wavelength range, and a 10/sup -9/ BER can be achieved for all channels.