Experimental demonstration of dynamic equalization of three 2.5-Gbit/s WDM channels over 1000 km using acousto-optic tunable filters

We demonstrate experimentally the dynamic equalization of the nonuniform EDFA gain by using acoustic-optic tunable filters with active feedback. After 1000 km transmission in a recirculating-loop experiment, the maximum power differential is reduced from 20 dB to 1 dB for three 2.5-Gbit/s WDM channels covering an 8-nm wavelength range. The active feedback is verified and ensures proper system performance when the power of any individual channel varies over time, as is likely in a dynamically-reconfigurable WDM network.