Theoretical analysis of carrier heating effect in quantum-dot semiconductor lasers based on a multi-level energy balance equations model

Abstract

Abstract In this paper, we develop a self-consistent numerical approach for quantum-dot (QD) semiconductor lasers which enables us to dynamically describe the charge-carrier temperature in the wetting layer (WL) and within the QDs during the laser operation. The self-consistent analysis of the WL-QD system is performed using an asymmetric multi-population rate-equation model with a multi-level energy balance equations approach. An important aspect of the model is that the carrier scattering dynamics in the combined WL-QD system is described by Coulomb scattering rates, and these rates are incorporated into the laser dynamical equations as nonlinear functions of the electron and hole densities in the WL. Using the presented model, the impact of carrier heating on the steady-state, turn-on dynamics and small-signal modulation response of QD lasers is investigated. As a main result it is shown that the carrier temperature in the WL is sufficiently higher than the carrier temperature inside the QDs, because the WL is the main origin of all carrier–carrier collisions in the system and, it not only acts as a carrier reservoir for QDs but can also inhibit the carrier heating inside the QDs.