- 标题
- 摘要
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- 实验方案
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Laser Raman scattering by graphene plasmons
摘要： A new scheme of Raman scattering of a laser by THz graphene plasmons in the presence of both space charge and electromagnetic surface plasmons is proposed. Plasmon–laser coupling arises through the two dimensional response of electrons in graphene. For optical frequency laser scattering by THz plasmons, phase matching conditions are satis?ed for near normal incidence and the Raman scattered wave also propagates normal to the graphene surface. The amplitude of the electric ?eld of the Raman scattered wave scales linearly with the plasmon density ?uctuation level and laser amplitude and inversely with the electron effective mass. Raman scattering would provide in situ diagnostics of the amplitude and frequency of the THz wave.
关键词： THz,diagnostics,Raman scattering,graphene plasmons,laser
更新于2025-09-23 15:19:57
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Graphene-Coated Nanowire Waveguides and Their Applications
摘要： In recent years, graphene‐coated nanowires (GCNWs) have attracted considerable research interest due to the unprecedented optical properties of graphene in terahertz (THz) and mid‐infrared bands. Graphene plasmons in GCNWs have become an attractive platform for nanoscale applications in subwavelength waveguides, polarizers, modulators, nonlinear devices, etc. Here, we provide a comprehensive overview of the surface conductivity of graphene, GCNW‐based plasmon waveguides, and applications of GCNWs in optical devices, nonlinear optics, and other intriguing fields. In terms of nonlinear optical properties, the focus is on saturable absorption. We also discuss some limitations of the GCNWs. It is believed that the research of GCNWs in the field of nanophotonics will continue to deepen, thus laying a solid foundation for its practical application.
关键词： graphene plasmons,mid‐infrared waves,graphene‐coated nanowires,waveguide
更新于2025-09-19 17:13:59
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Multipolar terahertz absorption spectroscopy ignited by graphene plasmons
摘要： Terahertz absorption spectroscopy plays a key role in physical, chemical and biological systems as a powerful tool to identify molecular species through their rotational spectrum fingerprint. Owing to the sub-nanometer scale of molecules, radiation-matter coupling is typically dominated by dipolar interaction. Here we show that multipolar rotational spectroscopy of molecules in proximity of localized graphene structures can be accessed through the extraordinary enhancement of their multipolar transitions provided by terahertz plasmons. In particular, specializing our calculations to homonuclear diatomic molecules, we demonstrate that a micron-sized graphene ring with a nano-hole at the core combines a strong near-field enhancement and an inherently pronounced field localization enabling the enhancement of the dipole-forbidden terahertz absorption cross-section of H+2 by 8 orders of magnitude. Our results shed light on the strong potential offered by nano-structured graphene as a robust and electrically tunable platform for multipolar terahertz absorption spectroscopy at the nanoscale.
关键词： graphene plasmons,multipolar transitions,nanoscale,Terahertz absorption spectroscopy
更新于2025-09-19 17:13:59
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Photonic crystal for graphene plasmons
摘要： Photonic crystals are commonly implemented in media with periodically varying optical properties. Photonic crystals enable exquisite control of light propagation in integrated optical circuits, and also emulate advanced physical concepts. However, common photonic crystals are un?t for in-operando on/off controls. We overcome this limitation and demonstrate a broadly tunable two-dimensional photonic crystal for surface plasmon polaritons. Our platform consists of a continuous graphene monolayer integrated in a back-gated platform with nano-structured gate insulators. Infrared nano-imaging reveals the formation of a photonic bandgap and strong modulation of the local plasmonic density of states that can be turned on/off or gradually tuned by the applied gate voltage. We also implement an arti?cial domain wall which supports highly con?ned one-dimensional plasmonic modes. Our electrostatically-tunable photonic crystals are derived from standard metal oxide semiconductor ?eld effect transistor technology and pave a way for practical on-chip light manipulation.
关键词： graphene plasmons,tunable,infrared nano-imaging,Photonic crystal,surface plasmon polaritons
更新于2025-09-11 14:15:04
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Theoretical Analysis of Tunable Multimode Coupling in a Grating-Assisted Double-Layer Graphene Plasmonic System
摘要： A double-layer graphene hybrid system is proposed to investigate the multimode coupling at far-infrared frequencies. With the assistance of metallic grating, the upper- and lower-layer graphene surface plasmons as well as the magnetic polaritons can be excited simultaneously, resulting in selective localization of electromagnetic energy. By tuning the thickness of the spacer, the mutual conversion between strong coupling and weak coupling can be achieved, giving rise to hybrid modes and Rabi splitting. The dynamic control of multimode coupling is also investigated via varying the Fermi energy of graphene. The hybrid coupling behaviors exhibit unique energy-transfer and multiband light trapping as well as mode splitting characteristics, which is well described by the classical coupled oscillator model. Our work may inspire related studies on graphene-based light-matter interaction, and the proposed hybrid system provides a good paradigm for designing many plasmonic devices, including tunable optical switches, thermal emitters, multiband absorbers, sensors, etc.
关键词： graphene plasmons,energy-transfer,coupled oscillator model,absorption enhancement,magnetic polaritons
更新于2025-09-11 14:15:04
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Bulk and surface plasmons in graphene finite superlattices
摘要： In recent years, graphene plasmonics, has attracted significant interest motivated by graphene's unique high carrier mobility, electrically or chemically tunable carrier density, long-lived and strong plasmon excitation confinement. In the context of optoelectronics and nanophotonics, graphene is considered as promising plasmonic material working in the mid-infrared and terahertz spectral windows. However, in a single layer graphene, the electromagnetic energy has a limited capability to plasmon excitations. To obtain a more powerful capacity of excite plasmon resonance, one can employ multilayer graphene structures as possible solution. In this work, we find an analytical expression for the dielectric function of the N-layer graphene structure solving a recurrence relation between the electric potential at different graphene layers. We also find that the highest energy of the plasmon oscillations supported by the multilayer graphene stacks at long wavelength correspond to electrons in each plane oscillating in phase. In addition, a surface plasmon mode emerges at certain finite wave vector outside the bulk plasmon band and it is Landau damping in the continuous interband single particle excitation with increasing wave vector.
关键词： Recursive approximation,Graphene,Plasmons in finite superlattices
更新于2025-09-09 09:28:46