Nano-optical imaging of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>WS</mml:mi><mml:msub><mml:mi mathvariant="normal">e</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>waveguide modes revealing light-exciton interactions

Fei, Zhe; Scott, Marie; Gosztola, David J.; Foley, Jonathan J.; Yan, Jiaqiang; Mandrus, David; Wen, Haidan; Zhou, Peng; Zhang, D. W.; Sun, Yinghui; Guest, Jeffrey R.; Gray, Stephen K.; Bao, Wenzhong; Wiederrecht, Gary P.; Xu, Xiaodong

doi:10.1103/physrevb.94.081402

Cited by 93 publications

(59 citation statements)

References 36 publications

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“…The lower-k part of the exciton polariton-guided waves (Fig. 1F) has been imaged in thin WSe 2 crystals under ambient conditions (45), in a regime where these propagating modes have a dominant photon character (Fig. 1F).…”

Section: High-temperature Exciton Polaritonsmentioning

confidence: 99%

Polaritons in van der Waals materials

Basov

Fogler

Abajo

2016

Science

981

843

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Polaritons in van der Waals (vdW) materials. Polaritons-a hybrid of light-matter oscillations-can originate in different physical phenomena: conduction electrons in graphene and topological insulators (surface plasmon polaritons), infrared-active phonons in boron nitride (phonon polaritons), excitons in dichalcogenide materials (exciton polaritons), superfluidity in FeSe-and Cu-based superconductors with high critical temperature T c (Cooper-pair polaritons), and magnetic resonances (magnon polaritons). The family of vdW materials supports all of these polaritons. The matter oscillation component results in negative permittivity (e B < 0) of the polaritonic material, giving rise to optical-field confinement at the interface with a positive-permittivity (e A > 0) environment. vdW polaritons exhibit strong confinement, as defined by the ratio of incident light wavelength l 0 to polariton wavelength l p .

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Section: High-temperature Exciton Polaritonsmentioning

confidence: 99%

Polaritons in van der Waals materials

Basov

Fogler

Abajo

2016

Science

981

843

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“…One broad implication of our work is that nanoimaging of collective modes can reveal nontrivial electron properties, in this case, 1D bound states. Recent experiments have demonstrated that this technique is not limited to plasmons or graphene or 2D systems [27][28][29][30] . We hope that our work stimulates even wider use of this novel spectroscopic tool.…”

mentioning

confidence: 99%

Tunable Plasmonic Reflection by Bound 1D Electron States in a 2D Dirac Metal

Jiang

Pan

et al. 2016

Phys. Rev. Lett.

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We show that surface plasmons of a two-dimensional Dirac metal such as graphene can be reflected by line-like perturbations hosting one-dimensional electron states. The reflection originates from a strong enhancement of the local optical conductivity caused by optical transitions involving these bound states. We propose that the bound states can be systematically created, controlled, and liquidated by an ultranarrow electrostatic gate. Using infrared nanoimaging, we obtain experimental evidence for the locally enhanced conductivity of graphene induced by a carbon nanotube gate, which supports this theoretical concept.Plasmon scattering and plasmon losses in Dirac materials, such as graphene and topological insulators, are problems of interest to both fundamental and applied research. It is an outstanding challenge to understand various kinds of interaction (electron-electron, electron-phonon, electron-photon, electron-disorder) responsible for these complex phenomena [1][2][3][4][5] . At the same time, control of plasmon scattering is critical if this class of materials is to become a new platform for nanophotonics [6][7][8][9] .One source of plasmon scattering is long-range inhomogeneity of the electron density, which causes local fluctuations in the plasmon wavelength λ p . If the inhomogeneities are weak, those of size comparable to the average λ p are expected to be the dominant scatterers 10,11 Surprisingly, recent experiments have revealed that one-dimensional (1D) defects of nominally atomic width can act as effective reflectors for plasmons with wavelengths as large as a few hundred nm. Strong plasmon reflection was observed near grain boundaries 12,13 , topological stacking faults 14 , as well as nanometerscale wrinkles and cracks 11,12 in graphene. If this anomalous reflection is indeed an ubiquitous effect largely unrelated to the specific nature of a defect, it calls for a universal explanation. In this Letter we attribute its origin to electron bound states commonly occurring near 1D defects. We show that optical transitions involving the bound states can produce strong dissipation at small distances x from the defect and therefore, alter plasmon dynamics. To support this idea we present a theoretical analysis of an exactly solvable model, which illustrates qualitative and quantitative characteristics of the bound states and predicts how their optical response depends on the tunable parameters of a 1D potential well. We also report an attempt to probe the predicted effects experimentally. Our approach is to employ an ultranarrow electric gate in the form of a carbon nanotube (CNT) to create a precisely tunable 1D barrier in graphene. This device enables a systematic investigation and control of plasmon propagation, including, in principle, an implementation of a plasmon on-off switch (Fig. 1). What we find is that the measured real-space profile of the plasmon amplitude (Fig. 4) cannot be accounted for by a local change in λ p alone. Instead, the data are consistent with the presence of an enhanced ...

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“…Strong excitonic resonances, especially the A and B resonances associated with direct transitions between the two spin-orbit split valence band (VB) maxima and the conduction band (CB) minimum at the K point [22] dominate their optical spectra. In microcavities [23][24][25] or waveguides [26,27], single-and few-layer TMDs exhibit exciton-polaritons originating from strong coupling. Besides the two-dimensional platelets, TMDs also form fullerenelike structures and nanotubes (NTs) [28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”

Section: Introductionmentioning

confidence: 99%

Ultrafast nonequilibrium dynamics of strongly coupled resonances in the intrinsic cavity of WS2 nanotubes

Višić

Yadgarov

Pogna

et al. 2019

Phys. Rev. Research

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Strong coupling of electric transition dipoles with optical or plasmonic resonators modifies their light-matter interaction and, therefore, their optical spectra. Semiconducting WS 2 nanotubes intrinsically provide the dipoles through their excitonic resonances, and the optical cavity via their cylindrical shape. We investigate the nonequilibrium light-matter interaction in WS 2 nanotubes in the time domain using femtosecond transient extinction spectroscopy. We develop a phenomenological coupled oscillator model with time-dependent parameters to describe the transient extinction spectra, allowing us to extract the underlying nonequilibrium electron dynamics. We find that the exciton and trion resonances shift due to many-body effects of the photogenerated charge carriers and their population dynamics on the femto-and picosecond timescale. Our results show that the time-dependent phenomenological model quantitatively reproduces the nonequilibrium optical response of strongly coupled systems.

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Nano-optical imaging ofWSe2waveguide modes revealing light-exciton interactions

Cited by 93 publications

References 36 publications

Polaritons in van der Waals materials

Polaritons in van der Waals materials

Tunable Plasmonic Reflection by Bound 1D Electron States in a 2D Dirac Metal

Ultrafast nonequilibrium dynamics of strongly coupled resonances in the intrinsic cavity of WS2 nanotubes

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