Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 46: Graphene: Dynamics (O with HL/TT)

HL 46.5: Vortrag

Mittwoch, 18. März 2015, 11:30–11:45, MA 041

Theory of coherent light emission in graphene — •Roland Jago, Torben Winzer, Andreas Knorr, and Ermin Malic — Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Germany

Within the density matrix formalism we present a microscopic and full quantized theoretical description of the coupled carrier, phonon and photon dynamics in graphene implemented in a photonic crystal nanocavity. We demonstrate that under strong optical excitation a spectrally broad and long-lived population inversion can be achieved. In the case of free-standing graphene non-radiative Coulomb-induced carrier-recombination on a femtosecond time scale prevents an efficient emission of coherent photons. To partially suppress this ultrafast recombination, we propose to support graphene on a substrate having high-dielectric screening. In this case, our calculations reveal a temporarily extended population inversion, that remains stable up to some tens of picoseconds under realistic conditions. In particular we observe the emission of coherent laser light suggesting graphene as gain medium for lasers [2].

[1] T. Winzer, E. Malic and A. Knorr, Phys. Rev. B 87, 165413 (2013) [2] R. Jago, T. Winzer, A. Knorr and E. Malic, arXiv:1409.8182 (2014)