Compensation of nonlinearity in semiconductor optical amplifiers

The nonlinearity inherent in semiconductor optical amplifiers can cause adverse system effects, such as intermodulation distortion (IMD) in FDM systems, crosstalk in on/off-keying WDM systems, and pulse distortion in multi-Gbit/s on/offkeying systems. We present a practical, feed-forward linearisation scheme that is capable of reducing these effects significantly. A two-tone experiment confirms the reduction of the IMD by about 14 dB.