The Influence of the Excited State (ES) Lasing in Quantum Dot-in-a-Well (QDWELL) Structure on the QDWELL Laser Performance in Optical Communication Systems

摘要

Recently, the theoretical model of the quantum dot (QD) semiconductor lasers has been developed where the excited state (ES) lasing has been taking into account. It has been shown that the ES QD semiconductor laser demonstrates a larger modulation bandwidth, lower frequency chirp and a smaller line enhancement factor (LEF) as compared to the ground state (GS) QD semiconductor lasers. The applications of high-speed directly modulated ES lasers in future optical communications is possible. In this paper, we investigated theoretically the 4 level pulse amplitude modulation (4-PAM) and 8 level PAM (8-PAM) formats of the ES QDWELL laser. We solved numerically the modified rate equation system and have shown that is such cases the QDWELL laser modulation bandwidth is substantially increased.