Microscopic mechanism underlying double-state lasing in an InAs/GaAs quantum dot laser diode elucidated using coupled rate equations and the spontaneous emission recorded from a window structure

• Published in: Optics express Vol. 23; no. 25; pp. 31682 - 31690
• Main Authors: Lee, J M, Jeon, B H, Kim, J, Lee, D
• Format: Journal Article
• Language: English
• Published: United States 14.12.2015
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.23.031682

We investigated the microscopic mechanism underlying the double-state lasing behavior (simultaneous lasing at the ground state [GS] and excited state [ES]) in InAs/GaAs quantum dot (QD) laser diodes. The ES and GS lasing processes that contributed to double-state lasing were examined experimentally and theoretically. Experiments were conducted in which spontaneous emission from a window of a QD laser diode was examined under lasing conditions, and numerical simulations were performed using a coupled rate equation model of the QD microstates. The findings showed that, when carrier relaxation from the ES to the GS was sufficiently slow, double-state lasing occurred. Additionally, ES lasing was found to arise not from the QD group undergoing GS lasing, but rather from another QD group in which the states were lower in energy and outside of the homogeneous bandwidth.