Investigation of spatial hole burning and linewidth enhancement factor impact on distributed-feedback quantum cascade lasers dynamics

In this manuscript, we employ a time-domain traveling-wave model with a coupled-mode theory to characterize the dynamic behavior of a mid-Infrared (MIR) Quantum Cascade Laser (QCL) in the Distributed-Feedback (DFB) configuration. Our investigation underscores the crucial influence of the linewidth enhancement factor (LEF) and spatial hole burning (SHB) on the single-mode behavior of DFB QCLs. Disregarding these factors leads to an overestimation of the range of pump currents granting single-mode emission and results in an inaccurate simulation of the multimodal dynamics of DFB QCLs. The numerical simulations presented in this work closely align with experimental observations, specifically focusing on a DFB QCL operating at a wavelength of 9.34 μm.