arXiv subjects

M. F. Pereira Jr.

Publications and source records attributed to M. F. Pereira Jr..

2 recordsLinked to original sources

arXiv2007

Fingerprints of spatial charge transfer in Quantum Cascade Lasers

We show that mid infrared transmission spectroscopy of a quantum cascade laser provides clear cut information on changes in charge location at different bias. Theoretical simulations of the evolution of the gain/absorption spectrum for the $λ\sim$ 7.4 $μ$m InGaAs/AlInAs/InP quantum cascade laser have been compared with the experimental findings. Transfer of electrons between the ground states in the active region and the states in the injector goes in hand with a decrease of discrete intersubband absorption peaks and an increase of broad high-energy absorption towards the continuum delocalised states above the barriers.

cond-mat.mes-hall↗

arXiv2004

Controlling many-body effects in the midinfrared gain and THz absorption of quantum cascade laser structures

A many-body theory based on nonequilibrium Green functions, in which transport and optics are treated on a microscopic quantum mechanical basis, is used to compute gain and absorption in the optical and THz regimes in quantum cascade laser structures. The relative importance of Coulomb interactions for different intersubband transitions depends strongly on the spatial overlap of the wavefunctions and the specific nonequilibrium populations within the subbands. The magnitude of the Coulomb effects can be controlled by changing the operation bias.

cond-mat.other↗