Quantum cascade lasers are unipolar semiconductor lasers covering a wide range of the
infrared and terahertz spectrum. Lasing action is achieved by using optical intersubband …

We develop simple density-matrix models to describe the role of coherence in resonant-
tunneling (RT) transport of quantum-cascade lasers (QCLs). Specifically, we investigate the …

We analyze theoretically several crucial performance aspects of terahertz quantum cascade
lasers, such as the impact of doping on the threshold current, the relative importance of the …

A simulation scheme based on nonequilibrium Green's functions for biased periodic
semiconductor heterostructure devices is presented in detail. The implementation can …

A simplified density-matrix model describing the population and coherence terms of four
states in a resonant phonon scattering based terahertz quantum cascade laser is presented …

A general theoretical approach to study the quantum kinetics in a system coupled to a bath
is proposed. Starting with the microscopic interaction, a Lindblad master equation is …

A lasing scheme for terahertz quantum cascade lasers, based on consecutive phonon-
photon-phonon emissions per module, is proposed and experimentally demonstrated. The …

Quantum cascade lasers are semiconductor devices based on the interplay of perpendicular
transport through the heterostructure and the intracavity lasing field. We employ …

We study the operation of an 8.5 μm quantum cascade laser based on GaInAs/AlInAs lattice
matched to InP using three different simulation models based on density matrix (DM) and …

Transport and gain properties of a resonant-phonon terahertz quantum cascade laser are
calculated using nonequilibrium Green's functions. Impurity scattering is shown to be …