Abstract
Optical channel pre‐emphasis equalization is experimentally researched for a 270 km 40 × 40 Gbit/s WDM transmission system with three EDFAs concatenated as booster amplifier. The channel imbalance of the overall system changes with different sets of power launched into EDFAs. Appropriately choosing the power input to concatenated EDFAs can make the output spectrum of 40‐channel signal be equalized to the most extent. The merit of benefit can be around 5.5 dB by this pre‐emphasis equalization. The requirement for the gain equalizer is therefore greatly released although still necessary. To take the channel imbalance of transmitter signal into account, the gain imbalance of the overall system almost matches the power imbalance of 40 channels, but the significant difference lies at some channels. Finally, the pump power into Raman amplifier is also optimized, and another 1.3‐dB improvement of channel balance can be further achieved. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1632–1634, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23450