Carrier tunneling in complex asymmetrical multiple-quantum-well semiconductor optical amplifiers

A numerical model for calculation of the ultrafast gain properties of asymmetrical multiple-quantum-well (AMQW) semiconductor optical amplifiers is extended with more exact calculation of tunneling times for each barrier and different directions of the propagation. Results show the necessity of considering the tunneling effect between the nonidentical QWs if the thickness of barriers is less than 10 nm. Without taking the tunneling effects into account, there is a large disagreement with slow recovery times. We have shown how tunneling effects, incorporated into the dynamical model, allow a better understanding of the slow gain recovery time decreasing. Theoretical results show good agreement with experimental data.