Voltage-Controlled and Injector Layer Thickness-Dependent Tuning of Quantum Cascade Laser for Terahertz Spectroscopy.

This work presents a numerical study of the tuning capabilities of quantum cascade lasers (QCLs) in terahertz imaging systems. This frequency range allows precise molecular identification without damaging the substance. QCL tuning is achieved by adjusting the power supply and the geometric dimensions of the injector region. Using the authors' Infinite and Finite Model of Superlattice (IMSL and FMSL) approach, the model quickly predicts tuning trends, which are then validated with detailed radiation maps generated by the Real Space Model (RSM). Numerical results reveal a high sensitivity of the QCL optical gain to injector width variations, enabling the creation of either multiple separate tuning regions or a single continuous tuning region with minimal spectral shift.