Modeling quantum dot lasers with optical feedback: sensitivity of bifurcation scenarios

TLDR

The study investigates the complex dynamics of a quantum dot laser under short‑cavity optical feedback, exploring how tuning phase–amplitude coupling and confinement factor leads to various dynamical regimes toward conventional quantum‑well lasers. A Lang–Kobayashi–type field model coupled with microscopic rate equations for electrons, holes, and the wetting layer is used, and the feedback strength is varied to analyze bifurcation scenarios via time‑series, spectra, and phase portraits. Optical feedback induces multistability in the model, manifesting as external cavity modes or delay‑induced intensity pulsations.

Abstract

Abstract We present a systematic study of the complex dynamics of a quantum dot (QD) laser subjected to optical feedback from a short external cavity. Our model consists of a Lang–Kobayashi like model for the electric field combined with a microscopically based rate equation system. We separately treat electron and hole dynamics in the QDs and the surrounding wetting layer (WL). By tuning the phase–amplitude coupling and the optical confinement factor we are able to discuss various scenarios of the dynamics on the route towards conventional quantum well (QW) lasers. Due to the optical feedback, multistability occurs in our model in form of external cavity modes (ECMs) or delay‐induced intensity pulsations. In dependence of the feedback strength we analyze complex bifurcation scenarios for the intensity of the emitted laser light as well as time series, power spectra, and phase portraits of all dynamic variables in order to elucidate the internal dynamics of the laser.