Broadband gate-tunable terahertz plasmons in graphene heterostructures

Graphene, a unique two-dimensional material comprising carbon in a honeycomb lattice 1 , has brought breakthroughs across electronics, mechanics and thermal transport, driven by the quasiparticle Dirac fermions obeying a linear dispersion 2 , 3 . Here, we demonstrate a counter-pumped all-optical dif...

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Bibliographic Details
Published inNature photonics Vol. 12; no. 1; pp. 22 - 28
Main Authors Yao, Baicheng, Liu, Yuan, Huang, Shu-Wei, Choi, Chanyeol, Xie, Zhenda, Flor Flores, Jaime, Wu, Yu, Yu, Mingbin, Kwong, Dim-Lee, Huang, Yu, Rao, Yunjiang, Duan, Xiangfeng, Wong, Chee Wei
Format Journal Article
LanguageEnglish
Published London Nature Publishing Group UK 01.01.2018
Nature Publishing Group
Subjects
140/125
639/301/357/918
639/624/400/1021
639/766/400/1105
639/925/918/1054
Applied and Technical Physics
Bandwidths
Broadband
Energy conservation
Fermions
Graphene
Heterostructures
Honeycomb construction
Landau damping
Letter
Phase matching
Physics
Physics and Astronomy
Plasmons
Quantum Physics
Signal processing
Terahertz frequencies
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Summary:Graphene, a unique two-dimensional material comprising carbon in a honeycomb lattice 1 , has brought breakthroughs across electronics, mechanics and thermal transport, driven by the quasiparticle Dirac fermions obeying a linear dispersion 2 , 3 . Here, we demonstrate a counter-pumped all-optical difference frequency process to coherently generate and control terahertz plasmons in atomic-layer graphene with octave-level tunability and high efficiency. We leverage the inherent surface asymmetry of graphene for strong second-order nonlinear polarizability 4 , 5 , which, together with tight plasmon field confinement, enables a robust difference frequency signal at terahertz frequencies. The counter-pumped resonant process on graphene uniquely achieves both energy and momentum conservation. Consequently, we demonstrate a dual-layer graphene heterostructure with terahertz charge- and gate-tunability over an octave, from 4.7 THz to 9.4 THz, bounded only by the pump amplifier optical bandwidth. Theoretical modelling supports our single-volt-level gate tuning and optical-bandwidth-bounded 4.7 THz phase-matching measurements through the random phase approximation, with phonon coupling, saturable absorption and below the Landau damping, to predict and understand graphene plasmon physics. An all-optical difference frequency process is exploited to generate terahertz graphene plasmons that are tunable over an octave.
ISSN:1749-4885
1749-4893
DOI:10.1038/s41566-017-0054-7