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Room temperature Terahertz stimulated emission and population inversion in optically pumped graphene is reported. We experimentally observe fast relaxation and relatively slow recombination dynamics of photogenerated electrons/holes in an…

Materials Science · Physics 2012-08-27 Stephane Boubanga Tombet , Silvia Chan , Taiichi Otsuji , Akira Satou , and Victor Ryzhii

Electrons moving in graphene behave as massless Dirac fermions, and they exhibit fascinating low-frequency electrical transport phenomena. Their dynamic response, however, is little known at frequencies above one terahertz (THz). Such…

We investigate the contribution of charge puddles to the non-vanishing conductivity minimum in disordered graphene flakes at the charge neutrality point. For that purpose, we study systems with a geometry that suppresses the transmission…

Mesoscale and Nanoscale Physics · Physics 2016-01-13 Leandro R. F. Lima , Caio H. Lewenkopf

We model the low energy dynamics of graphene in the continuum in terms of a version of Reduced Quantum Electrodynamics restricting fermions to a (2+1)-dimensional brane, whilst photons remain within the (3+1)-dimensional bulk. For charge…

Mesoscale and Nanoscale Physics · Physics 2016-05-25 Saúl Hernández-Ortiz , David Valenzuela , Alfredo Raya , Saúl Sánchez-Madrigal

The linear electrodynamic properties of graphene -- the frequency-dependent conductivity, the transmission spectra and collective excitations -- are briefly outlined. The non-linear frequency multiplication effects in graphene are studied,…

Mesoscale and Nanoscale Physics · Physics 2009-05-27 S. A. Mikhailov

Relativistic quantum theory of induced scattering of 2D Dirac particles by electrostatic field of impurity ion (in the Born approximation) in the doped graphene at the presence of an external electromagnetic radiation field (actually…

Optics · Physics 2017-11-22 A. K. Avetissian , A. G. Ghazaryan , Kh. V. Sedrakian , B. R. Avchyan

The conductance, the transmission and the reflection probabilities through rectangular potential barriers and pn-junctions are obtained for bilayer graphene taking into account the four bands of the energy spectrum. We have evaluated the…

Mesoscale and Nanoscale Physics · Physics 2013-05-28 B. Van Duppen , F. M. Peeters

The analysis of Current-voltage characteristic and Ampere-Gauss characteristic for graphene with Hubbard interaction was carried out depending on frequency of external variable field and magnetic field. The regions of the absolute negative…

Mesoscale and Nanoscale Physics · Physics 2010-03-16 Mikhail Belonenko , Nikolay Lebedev , Masgut Shakirzyanov , Natalia Yanyushkina

We analyze intrinsic nonlinearities in two-dimensional polaritonic materials interacting with an optical wave. Focusing on the case of graphene, we show that the second-order nonlinear optical conductivity due to carrier density…

Mesoscale and Nanoscale Physics · Physics 2019-07-24 Christian Wolff , Christos Tserkezis , N. Asger Mortensen

Photon-assisted charge transport through a double barrier laser structure, separated by a region assisted by a magnetic field, is studied. Employing Floquet theory and matrix formalism, the transmission probabilities for the central band…

Mesoscale and Nanoscale Physics · Physics 2024-10-18 Rachid El Aitouni , Miloud Mekkaoui , Abdelhadi Bahaoui , Ahmed Jellal

The optical properties of graphene are made unique by the linear band structure and the vanishing density of states at the Dirac point. It has been proposed that even in the absence of a semiconducting bandgap, a relaxation bottleneck at…

The unique terahertz properties of graphene has been identified for novel optoelectronic applications. In a graphene sample with bias voltage added, there is an enhanced absorption in the far infrared region and a diminished absorption in…

Mesoscale and Nanoscale Physics · Physics 2017-05-18 Yuan Yang , Grigory Kolesov , Lucas Kocia , Eric J. Heller

The independence of the dynamic conductivity of intrinsic graphene of frequency takes its origin in the compensation of the vanishing density of states by the diverging matrix element of the corresponding interband transition. The…

Mesoscale and Nanoscale Physics · Physics 2009-12-08 E. G. Mishchenko

We have fabricated a centimeter-size single-layer graphene device, with a gate electrode, which can modulate the transmission of terahertz and infrared waves. Using time-domain terahertz spectroscopy and Fourier-transform infrared…

Graphene-based photodetectors have shown responsivities up to 10$^8$A/W and photoconductive gains up to 10$^{8}$ electrons per photon. These photodetectors rely on a highly absorbing layer in close proximity of graphene, which induces a…

We numerically calculate the optical conductivity of twisted graphene bilayers within the continuum model. To obtain the imaginary part, we employ the regularized Kramers-Kronig relation allowing us to discuss arbitrary twist angles,…

Mesoscale and Nanoscale Physics · Physics 2013-12-03 Tobias Stauber , Pablo San-Jose , Luis Brey

We theoretically revisit graphene transport properties as a function of carrier density, taking into account possible correlations in the spatial distribution of the Coulomb impurity disorder in the environment. We find that the charged…

Mesoscale and Nanoscale Physics · Physics 2011-10-06 Qiuzi Li , E. H. Hwang , E. Rossi , S. Das Sarma

Attosecond dynamics of electron transmission through atomically-thin crystalline films is studied with an {\em ab initio} scattering theory. The temporal character of the electron propagation through graphene multilayers is traced to the…

Materials Science · Physics 2025-06-10 E. E. Krasovskii , R. O. Kuzian

We study nonequilibrium carriers (electrons and holes) in an intrinsic graphene at low temperatures under far- and mid-infrared (IR) radiation in a wide range of its intensities. The energy distributions of carriers are calculated using a…

Materials Science · Physics 2010-06-29 A. Satou , F. T. Vasko , V. Ryzhii

Exploration of optical non-linear response of graphene predominantly relies on ultra-short time domain measurements. Here we propose an alternate technique that uses frequency modulated continuous wavefront optical fields, thereby probing…

Mesoscale and Nanoscale Physics · Physics 2019-03-18 Ashutosh Singh , Saikat Ghosh , Amit Agarwal