scholarly journals Terahertz response of monolayer and few-layer WTe2 at the nanoscale

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ran Jing ◽  
Yinming Shao ◽  
Zaiyao Fei ◽  
Chiu Fan Bowen Lo ◽  
Rocco A. Vitalone ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Near Field ◽  
Transition Metal Dichalcogenide ◽  
Imaging Data ◽  
Metallic Behavior ◽  
Thermally Activated ◽  
Electromagnetic Responses ◽  
Thz Range ◽  
Layered Transition Metal ◽  
Plasmon Polaritons

AbstractTungsten ditelluride (WTe2) is an atomically layered transition metal dichalcogenide whose physical properties change systematically from monolayer to bilayer and few-layer versions. In this report, we use apertureless scattering-type near-field optical microscopy operating at Terahertz (THz) frequencies and cryogenic temperatures to study the distinct THz range electromagnetic responses of mono-, bi- and trilayer WTe2 in the same multi-terraced micro-crystal. THz nano-images of monolayer terraces uncovered weakly insulating behavior that is consistent with transport measurements. The near-field signal on bilayer regions shows moderate metallicity with negligible temperature dependence. Subdiffractional THz imaging data together with theoretical calculations involving thermally activated carriers favor the semimetal scenario with $$\Delta \approx -10\,{{{\rm{meV}}}}$$ Δ ≈ − 10 meV over the semiconductor scenario for bilayer WTe2. Also, we observed clear metallic behavior of the near-field signal on trilayer regions. Our data are consistent with the existence of surface plasmon polaritons in the THz range confined to trilayer terraces in our specimens. Finally, data for microcrystals up to 12 layers thick reveal how the response of a few-layer WTe2 asymptotically approaches the bulk limit.

scholarly journals Terahertz response of monolayer and few-layer WTe_2 at the nanoscale

2020 ◽  
Author(s):  
Ran Jing ◽  
Yinming Shao ◽  
Zaiyao Fei ◽  
Chiu Fan Bowen Lo ◽  
Francesco Ruta ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Near Field ◽  
Transition Metal Dichalcogenide ◽  
Imaging Data ◽  
Metallic Behavior ◽  
Thermally Activated ◽  
Number Of Layers ◽  
Electromagnetic Behavior ◽  
Thz Range ◽  
Plasmon Polaritons

Abstract Tungsten ditelluride (WTe_2) is a transition metal dichalcogenide whose physical properties depend critically on the number of layers. In this paper, we use apertureless scattering-type near-field optical microscopy operating at Terahertz (THz) frequencies and cryogenic temperatures to identify distinct THz range electromagnetic behavior of WTe_2 mono-, bi- and tri-layer terraces in the same micro-crystals. We observed clear metallic behavior of the near-field signal on tri-layer regions. Our data are consistent with the existence of surface plasmon polaritons (SPP) in the THz range confined to tri-layer terraces in our specimens. The near-field signal on bi-layer regions surprisingly shows moderately metallicity, but with negligible temperature dependence. Subdiffractional THz imaging data together with theoretical calculations considering thermally activated carriers favor the semimetal scenario over the semiconductor scenario for bi-layer WTe_2. THz images for monolayer terraces uncovered weakly insulating behavior consistent with transport data.

scholarly journals Quantifying photoinduced carriers transport in exciton–polariton coupling of MoS2 monolayers

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Min-Wen Yu ◽  
Satoshi Ishii ◽  
Shisheng Li ◽  
Ji-Ren Ku ◽  
Jhen-Hong Yang ◽  
...  
Keyword(s):  
Electronic Energy ◽  
Plasmonic Nanostructures ◽  
Transition Metal Dichalcogenide ◽  
Metallic Nanoparticle ◽  
Rabi Splitting ◽  
One Dimensional ◽  
Induced Dipole ◽  
Mos2 Monolayers ◽  
Plasmon Polaritons ◽  
Significant Attention

AbstractExciton–polariton coupling between transition metal dichalcogenide (TMD) monolayer and plasmonic nanostructures generates additional states that are rich in physics, gaining significant attention in recent years. In exciton–polariton coupling, the understanding of electronic-energy exchange in Rabi splitting is critical. The typical structures that have been adopted to study the coupling are “TMD monolayers embedded in a metallic-nanoparticle-on-mirror (NPoM) system.” However, the exciton orientations are not parallel to the induced dipole direction of the NPoM system, which leads to inefficient coupling. Our proposed one-dimensional plasmonic nanogrooves (NGs) can align the MoS2 monolayers’ exciton orientation and plasmon polaritons in parallel, which addresses the aforementioned issue. In addition, we clearly reveal the maximum surface potential (SP) change on intermediate coupled sample by the photo-excitation caused by the carrier rearrangement. As a result, a significant Rabi splitting (65 meV) at room temperature is demonstrated. Furthermore, we attribute the photoluminescence enhancement to the parallel exciton–polariton interactions.

scholarly journals Highly Stable Passively Q-Switched Erbium-Doped All-Fiber Laser Based on Niobium Diselenide Saturable Absorber

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4303
Author(s):  
Ping Hu ◽  
Jiajia Mao ◽  
Hongkun Nie ◽  
Ruihua Wang ◽  
Baitao Zhang ◽  
...  
Keyword(s):  
Fiber Laser ◽  
Saturable Absorber ◽  
Pulse Width ◽  
Nonlinear Optical ◽  
Modulation Depth ◽  
Transition Metal Dichalcogenide ◽  
Center Wavelength ◽  
Niobium Diselenide ◽  
Erbium Doped ◽  
Layered Transition Metal

A saturable absorber (SA) based on niobium diselenide (NbSe2), which is a layered transition metal dichalcogenide (TMD) in the VB group, is fabricated by the optically driven deposition method, and the related nonlinear optical properties are characterized. The modulation depth, saturable intensity, and nonsaturable loss of the as-prepared NbSe2 nanosheet-based SA are measured to be 16.2%, 0.76 MW/cm2, and 14%, respectively. By using the as-fabricated NbSe2 SA, a highly stable, passively Q-switched, erbium-doped, all-fiber laser is realized. The obtained shortest pulse width is 1.49 μs, with a pulse energy of 48.33 nJ at a center wavelength of 1560.38 nm. As far as we know, this is the shortest pulse duration ever obtained by an NbSe2 SA in a Q-switched fiber laser.

Ultra-broadband unidirectional launching of surface plasmon polaritons by a double-slit structure beyond the diffraction limit

Nanoscale ◽  
2014 ◽  
Vol 6 (22) ◽  
pp. 13487-13493 ◽  
Author(s):  
Jianjun Chen ◽  
Chengwei Sun ◽  
Hongyun Li ◽  
Qihuang Gong
Keyword(s):  
Surface Plasmon ◽  
Surface Plasmon Polaritons ◽  
Near Field ◽  
Diffraction Limit ◽  
Plasmonic Waveguide ◽  
Plasmon Polaritons ◽  
Double Slit

Based on the near-field interference of two slit apertures in a subwavelength plasmonic waveguide, an ultra-broadband unidirectional SPP launcher beyond the diffraction limit was experimentally realized. This ultra-small SPP launcher has important applications in high-integration plasmonic circuits.

scholarly journals Anisotropic excitation of surface plasmon polaritons on a metal film by a scattering-type scanning near-field microscope with a non-rotationally-symmetric probe tip

Nanophotonics ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 269-276 ◽  
Author(s):  
Frederik Walla ◽  
Matthias M. Wiecha ◽  
Nicolas Mecklenbeck ◽  
Sabri Beldi ◽  
Fritz Keilmann ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
Surface Plasmon Polaritons ◽  
Metal Film ◽  
Near Infrared ◽  
Near Field ◽  
Optical Microscope ◽  
Anisotropic Surface ◽  
Surface Wave Propagation ◽  
Rotationally Symmetric ◽  
Plasmon Polaritons

AbstractWe investigated the excitation of surface plasmon polaritons on gold films with the metallized probe tip of a scattering-type scanning near-field optical microscope (s-SNOM). The emission of the polaritons from the tip, illuminated by near-infrared laser radiation, was found to be anisotropic and not circularly symmetric as expected on the basis of literature data. We furthermore identified an additional excitation channel via light that was reflected off the tip and excited the plasmon polaritons at the edge of the metal film. Our results, while obtained for a non-rotationally-symmetric type of probe tip and thus specific for this situation, indicate that when an s-SNOM is employed for the investigation of plasmonic structures, the unintentional excitation of surface waves and anisotropic surface wave propagation must be considered in order to correctly interpret the signatures of plasmon polariton generation and propagation.

Flexible n-type thermoelectric materials by organic intercalation of layered transition metal dichalcogenide TiS2

2015 ◽  
Vol 14 (6) ◽  
pp. 622-627 ◽  
Author(s):  
Chunlei Wan ◽  
Xiaokun Gu ◽  
Feng Dang ◽  
Tomohiro Itoh ◽  
Yifeng Wang ◽  
...  
Keyword(s):  
Transition Metal ◽  
Thermoelectric Materials ◽  
Transition Metal Dichalcogenide ◽  
Layered Transition Metal

scholarly journals How the cosmic web induces intrinsic alignments of galaxies

2014 ◽  
Vol 11 (S308) ◽  
pp. 437-442 ◽  
Author(s):  
S. Codis ◽  
Y. Dubois ◽  
C. Pichon ◽  
J. Devriendt ◽  
A. Slyz
Keyword(s):  
Gravitational Lensing ◽  
Theoretical Calculations ◽  
Future Generation ◽  
Wide Field ◽  
Imaging Data ◽  
Weak Gravitational Lensing ◽  
Spatially Correlated ◽  
Hydrodynamical Simulation ◽  
Good Proxy ◽  
And Control

AbstractIntrinsic alignments are believed to be a major source of systematics for future generation of weak gravitational lensing surveys like Euclid or LSST. Direct measurements of the alignment of the projected light distribution of galaxies in wide field imaging data seem to agree on a contamination at a level of a few per cent of the shear correlation functions, although the amplitude of the effect depends on the population of galaxies considered. Given this dependency, it is difficult to use dark matter-only simulations as the sole resource to predict and control intrinsic alignments. We report here estimates on the level of intrinsic alignment in the cosmological hydrodynamical simulation Horizon-AGN that could be a major source of systematic errors in weak gravitational lensing measurements. In particular, assuming that the spin of galaxies is a good proxy for their ellipticity, we show how those spins are spatially correlated and how they couple to the tidal field in which they are embedded. We will also present theoretical calculations that illustrate and qualitatively explain the observed signals.

scholarly journals Towards rational design and optimization of near-field enhancement and spectral tunability of hybrid core-shell plasmonic nanoprobes

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Debadrita Paria ◽  
Chi Zhang ◽  
Ishan Barman
Keyword(s):  
Single Molecule ◽  
Rational Design ◽  
Near Infrared ◽  
Theoretical Calculations ◽  
Near Field ◽  
Field Enhancement ◽  
Infrared Region ◽  
Core Shell ◽  
Optimization Strategy ◽  
Design And Optimization

Abstract In biology, sensing is a major driver of discovery. A principal challenge is to create a palette of probes that offer near single-molecule sensitivity and simultaneously enable multiplexed sensing and imaging in the “tissue-transparent” near-infrared region. Surface-enhanced Raman scattering and metal-enhanced fluorescence have shown substantial promise in addressing this need. Here, we theorize a rational design and optimization strategy to generate nanostructured probes that combine distinct plasmonic materials sandwiching a dielectric layer in a multilayer core shell configuration. The lower energy resonance peak in this multi-resonant construct is found to be highly tunable from visible to the near-IR region. Such a configuration also allows substantially higher near-field enhancement, compared to a classical core-shell nanoparticle that possesses a single metallic shell, by exploiting the differential coupling between the two core-shell interfaces. Combining such structures in a dimer configuration, which remains largely unexplored at this time, offers significant opportunities not only for near-field enhancement but also for multiplexed sensing via the (otherwise unavailable) higher order resonance modes. Together, these theoretical calculations open the door for employing such hybrid multi-layered structures, which combine facile spectral tunability with ultrahigh sensitivity, for biomolecular sensing.

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