Density-matrix model for photon-driven transport in quantum cascade lasers

Abstract

We developed a time-dependent density-matrix model to study photon-assisted (PA) electron transport in quantum cascade lasers. The Markovian equation of motion for the density matrix in the presence of an optical field is solved for an arbitrary field amplitude. Level-broadening terms emerge from microscopic Hamiltonians and supplant the need for empirical parameters that are often employed in related approaches. We show that, in quantum cascade lasers with diagonal design, photon resonances have a pronounced impact on electron dynamics around and above the lasing threshold, an effect that stems from the large spatial separation between the upper and lower lasing states. With the inclusion of PA tunneling, the calculated current density and output power are in good agreement with experiment.

References in corpus (5)

• Observation of photon-assisted tunneling in optical lattices
• Density-matrix theory of the optical dynamics and transport in quantum cascade structures: The role of coherence
• Photon-induced carrier transport in high efficiency midinfrared quantum cascade lasers
• Nonequilibrium phonon effects in midinfrared quantum cascade lasers
• Time-dependent transport in open systems based on quantum master equations