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HL: Fachverband Halbleiterphysik
HL 40: THz and MIR Physics in Semiconductors
HL 40.2: Talk
Friday, September 9, 2022, 09:45–10:00, H33
Exploring mid-infrared transient gain in graphene — •Kalliopi Mavridou1,2, Angelika Seidl1,2, Rakesh Rana1, Alexej Pashkin1, Manfred Helm1,2, and Stephan Winnerl1 — 1Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, Dresden 01328, Germany — 2Faculty of Physics and Center for Advancing Electronics Dresden, Technische Universität Dresden, Dresden 01062, Germany
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In our study we employ a powerful method, namely a three-pulse pump-probe technique, that was first suggested by Kim et al.1, to explore the possibility to achieve transient gain photon energies below the optical phonon energy (∼ 200 meV) in graphene. Intriguingly, this technique is not widely established and to our knowledge has never been used in the mid- or far-infrared spectral range. The principle behind this method relies on the effect of a strong pre-pump pulse of 1.55 eV photons, which can cause a transient population inversion at lower energies. This population inversion is evidenced by a sign flip of the mid-infrared (86 meV photon energy) pump-probe signal that is related to either absorption or stimulated emission of mid-infrared photons of the pump beam. We present the results on multilayer graphene obtained under various experimental configurations. Our findings shed light into the completion of rapid thermalization via Coulomb scattering and carrier cooling via optical phonons.
1. Kim, K.; Urayama, J.; Norris, T.; Singh, J.; Phillips, J.; Bhattacharya, P. Appl. Phys. Lett., 2002, 81, 670-672.