Gain Stabilization and Performance Improvement Induced by a Holding Beam in Semiconductor Optical Amplifiers: Modeling and Experiments

Semiconductor optical amplifiers (SOAs), though available commercially for wideband operation, suffer from non linear distortions that become unacceptable for telecom systems operating at high data rates with advanced modulation formats. The use of a holding beam within the SOA's gain spectrum helps in mitigating such distortions. The holding beam saturates the gain, stabilizes it, and reduces fluctuations caused by input signal variations. However, it also leads to a decrease in the signal's gain. We develop a novel heuristic model for SOAs that incorporates the experimentally measurable gain compression and validate it through experiments. Our model offers an effective approach for accurately modeling SOAs as in-line amplifiers.