Enhancement of gain recovery rate and cross-gain modulation bandwidth using a two-electrode quantum-dot semiconductor optical amplifier

摘要

A two-electrode quantum-dot semiconductor optical amplifier (QD-SOA) is proposed to enhance gain recovery rate and cross-gain modulation (XGM) bandwidth. In the theoretical model, electron and hole dynamics as well as the carrier diffusion are accounted for in the quantum-dot rate equations, which are solved with forward and backward propagation equations of signal and amplified spontaneous emission. The simulation results show that two-electrode QD-SOA can distribute injection current density nonuniformly to maintain carriers in carrier reservoirs of quantum dot sufficient along the entire cavity length of the semiconductor optical amplifier, thus making gain saturation dynamics dominated by spectral hole burning at lower bias current than common QD-SOA. Besides, distributing more current density in the second section of the two-electrode QDSOA at higher bias can greatly accelerate gain recovery as well as expand the XGM bandwidth.