Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 62: Graphene: Dynamics (jointly with O, HL)
TT 62.2: Vortrag
Mittwoch, 18. März 2015, 10:45–11:00, MA 041
Non-linear luminescence and four-wave mixing from graphene, probed by femtosecond pulse shaping — •Richard Ciesielski1, Alberto Comin1, Matthias Handloser1, Torben Winzer2, Ermin Malic2, and Achim Hartschuh1 — 1Ludwig-Maximilians-Universität, AK Hartschuh, Butenandtstr. 5-11, 81377 München — 2Institut für Theoretische Physik, Nichtlineare Optik und Quantenelektronik, Technische Universität Berlin, Germany
Ultrafast optical excitation of graphene leads to two main nonlinear emission signals in the visible. The first was described as incoherent non-linear photoluminescence (NLPL). The second results from near-degenerate four-wave mixing which is extraordinarily strong in graphene as compared to other materials. We investigated the two types of emission for different layer thickness using confocal microscopy and a 15 fs pulsed laser at 1.55 eV with a pulse shaper. Spectrally resolved autocorrelation scans revealed a continuously decreasing decay time of the NLPL from 1.2 eV towards 2.8 eV. Comparing the dynamics observed for different layers allows us to identify the influence of substrate induced doping. Finally, we were able to separate a weaker third contribution induced by the microscopic polarization of graphene [1].
Financial support by the DFG through the Nanosystems Initiative Munich (NIM) and the ERC (NEWNANOSPEC) is gratefully acknowledged.
[1] T. Winzer, R. Ciesielski, M. Handloser et al., arXiv:1411.0531v1 (2014).