scholarly journals Nanofocusing of acoustic graphene plasmon polaritons for enhancing mid-infrared molecular fingerprints

Nanophotonics ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 2089-2095 ◽  
Author(s):  
Kirill V. Voronin ◽  
Unai Aseguinolaza Aguirreche ◽  
Rainer Hillenbrand ◽  
Valentyn S. Volkov ◽  
Pablo Alonso-González ◽  
...  
Keyword(s):  
Cross Sections ◽  
Near Field ◽  
Field Enhancement ◽  
Charge Carriers ◽  
Metallic Surface ◽  
Molecular Fingerprints ◽  
Mid Infrared ◽  
Scattering Cross Sections ◽  
Plasmon Polaritons ◽  
Mode Volume

AbstractMid-infrared (mid-IR) optical spectroscopy of molecules is of large interest in physics, chemistry, and biology. However, probing nanometric volumes of molecules is challenging because of the strong mismatch of their mid-infrared absorption and scattering cross-sections with the free-space wavelength. We suggest overcoming this difficulty by nanofocusing acoustic graphene plasmon polaritons (AGPs) – oscillations of Dirac charge carriers coupled to electromagnetic fields with extremely small wavelengths – using a taper formed by a graphene sheet above a metallic surface. We demonstrate that due to the appreciable field enhancement and mode volume reduction, the nanofocused AGPs can efficiently sense molecular fingerprints in nanometric volumes. We illustrate a possible realistic sensing sсenario based on AGP interferometry performed with a near-field microscope. Our results can open new avenues for designing tiny sensors based on graphene and other 2D polaritonic materials.

scholarly journals Near-field surface plasmon field enhancement induced by rippled surfaces

2017 ◽  
Vol 8 ◽  
pp. 956-967 ◽  
Author(s):  
Mario D’Acunto ◽  
Francesco Fuso ◽  
Ruggero Micheletto ◽  
Makoto Naruse ◽  
Francesco Tantussi ◽  
...  
Keyword(s):  
Surface Plasmon ◽  
Near Field ◽  
Field Enhancement ◽  
General Technique ◽  
Electric Field Polarization ◽  
Surface Patterns ◽  
Trial And Error Method ◽  
Plasmon Polaritons ◽  
Error Method

The occurrence of plasmon resonances on metallic nanometer-scale structures is an intrinsically nanoscale phenomenon, given that the two resonance conditions (i.e., negative dielectric permittivity and large free-space wavelength in comparison with system dimensions) are realized at the same time on the nanoscale. Resonances on surface metallic nanostructures are often experimentally found by probing the structures under investigation with radiation of various frequencies following a trial-and-error method. A general technique for the tuning of these resonances is highly desirable. In this paper we address the issue of the role of local surface patterns in the tuning of these resonances as a function of wavelength and electric field polarization. The effect of nanoscale roughness on the surface plasmon polaritons of randomly patterned gold films is numerically investigated. The field enhancement and relation to specific roughness patterns is analyzed, producing many different realizations of rippled surfaces. We demonstrate that irregular patterns act as metal–dielectric–metal local nanogaps (cavities) for the resonant plasmonic field. In turn, the numerical results are compared to experimental data obtained via aperture scanning near-field optical microscopy.

Plasmonics for Nanoimaging and Nanospectroscopy

2013 ◽  
Vol 67 (2) ◽  
pp. 117-125 ◽  
Author(s):  
Satoshi Kawata
Keyword(s):  
Surface Plasmons ◽  
Noble Metals ◽  
Slow Light ◽  
Near Field ◽  
Field Enhancement ◽  
Historical Overview ◽  
Light Effect ◽  
Photon Confinement ◽  
Plasmon Polaritons ◽  
Effect Of Surface

The science of surface plasmon polaritons, known as “plasmonics,” is reviewed from the viewpoint of applied spectroscopy. In this discussion, noble metals are regarded as reservoirs of photons exhibiting the functions of photon confinement and field enhancement at metallic nanostructures. The functions of surface plasmons are described in detail with an historical overview, and the applications of plasmonics to a variety of industry and sciences are shown. The slow light effect of surface plasmons is also discussed for nanoimaging capability of the near-field optical microscopy and tip-enhanced Raman microscopy. The future issues of plasmonics are also shown, including metamaterials and the extension to the ultraviolet and terahertz regions.

scholarly journals Enhanced Absorption with Graphene-Coated Silicon Carbide Nanowires for Mid-Infrared Nanophotonics

Nanomaterials ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 2339
Author(s):  
Patrick Rufangura ◽  
Iryna Khodasevych ◽  
Arti Agrawal ◽  
Matteo Bosi ◽  
Thomas G. Folland ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Spectral Range ◽  
Field Enhancement ◽  
Experimental Methods ◽  
Hybrid Nanostructure ◽  
Mid Infrared ◽  
Enhanced Absorption ◽  
The Core ◽  
Coupling Medium ◽  
Plasmon Polaritons

The mid-infrared (MIR) is an exciting spectral range that also hosts useful molecular vibrational fingerprints. There is a growing interest in nanophotonics operating in this spectral range, and recent advances in plasmonic research are aimed at enhancing MIR infrared nanophotonics. In particular, the design of hybrid plasmonic metasurfaces has emerged as a promising route to realize novel MIR applications. Here we demonstrate a hybrid nanostructure combining graphene and silicon carbide to extend the spectral phonon response of silicon carbide and enable absorption and field enhancement of the MIR photon via the excitation and hybridization of surface plasmon polaritons and surface phonon polaritons. We combine experimental methods and finite element simulations to demonstrate enhanced absorption of MIR photons and the broadening of the spectral resonance of graphene-coated silicon carbide nanowires. We also indicate subwavelength confinement of the MIR photons within a thin oxide layer a few nanometers thick, sandwiched between the graphene and silicon carbide. This intermediate shell layer is characteristically obtained using our graphitization approach and acts as a coupling medium between the core and outer shell of the nanowires.

Broadband mid-infrared plasmon-polaritons in metallic-dielectric interfaces

2021 ◽  
Author(s):  
Flávio Feres ◽  
Ingrid Barcelos ◽  
Dario Bahamon ◽  
João Levandoski ◽  
Andrea Mancini ◽  
...  
Keyword(s):  
Surface Plasmon Polariton ◽  
Hexagonal Boron Nitride ◽  
Near Field ◽  
Real Space ◽  
Strong Coupling Regime ◽  
General Effect ◽  
Mid Infrared ◽  
Dielectric Interfaces ◽  
Plasmon Polaritons ◽  
Group Velocities

Abstract We report real-space near-field images of mid-infrared (IR) surface plasmon-polariton (SPP) waves in the insulating/metal/insulating (IMI) heterostructure: hexagonal boron nitride/gold/silicon dioxide (hBN/Au/SiO2). The SPPs are observed in the 750 – 1500 cm-1 (~13.3 – ~6.7 μm) range, feature micrometer-sized wavelengths and propagation lengths (LSPP) exceeding 20 μm at room temperature. Comparatively, real-space mapping of SPP waves in the mid-IR has been shown only in graphene, but with nanometer sized-wavelength and LSPP ~ 10 μm at cryogenic temperatures. Interestingly, we show interference between different polariton types in the IMI since the lower momenta SPPs in the metal surface interfere with higher momenta hyperbolic phonon polaritons (HPhP) in the hBN top layer creating SPP-HPhP overlapped waves. In agreement with theory, we quantify momentum and damping governing the SPP waves. Tunability is discussed upon changing the IMI heterostructure. Our theory predicts SPP group velocities reaching 20 % of the light velocity in vacuum and 0.2 – 0.4 ps lifetimes. We further demonstrate that the SPP waves interact with SiO2 and hBN phonons in the strong coupling regime. As a general effect of the metal/dielectric interface, the mid-IR SPP waves can be compelling for fast metal-based plasmonics, whilst their ability to strongly couple to phonons can be further explored for enhanced sensing in the mid-IR.

scholarly journals Plasmons driven by single electrons in graphene nanoislands

Nanophotonics ◽  
2013 ◽  
Vol 2 (2) ◽  
pp. 139-151 ◽  
Author(s):  
Alejandro Manjavacas ◽  
Sukosin Thongrattanasiri ◽  
F. Javier García de Abajo
Keyword(s):  
Cross Sections ◽  
Near Infrared ◽  
Near Field ◽  
Field Enhancement ◽  
High Sensitivity ◽  
Quantum Mechanical ◽  
Single Electrons ◽  
Electromagnetic Simulations ◽  
Highly Sensitive ◽  
Infrared Wavelengths

AbstractPlasmons produce large confinement and enhancement of light that enable applications as varied as cancer therapy and catalysis. Adding to these appealing properties, graphene has emerged as a robust, electrically tunable material exhibiting plasmons that strongly depend on the density of doping charges. Here we show that adding a single electron to a graphene nanoisland consisting of hundreds or thousands of atoms switches on infrared plasmons that were previously absent from the uncharged structure. Remarkably, the addition of each further electron produces a dramatic frequency shift. Plasmons in these islands are shown to be tunable down to near infrared wavelengths. These phenomena are highly sensitive to carbon edges. Specifically, armchair nanotriangles display sharp plasmons that are associated with intense near-field enhancement, as well as absorption cross-sections exceeding the geometrical area occupied by the graphene. In contrast, zigzag triangles do not support these plasmons. Our conclusions rely on realistic quantum-mechanical calculations, which are in ostensible disagreement with classical electromagnetic simulations, thus revealing the quantum nature of the plasmons. This study shows a high sensitivity of graphene nanoislands to elementary charges, therefore emphasizing their great potential for novel nano-optoelectronics applications.

scholarly journals A Narrow-Band Multi-Resonant Metamaterial in Near-IR

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5140
Author(s):  
Farhan Ali ◽  
Serap Aksu
Keyword(s):  
Cross Sections ◽  
Narrow Band ◽  
Near Field ◽  
Impedance Matching ◽  
Perfect Absorber ◽  
Refractive Index Sensitivity ◽  
Perfect Absorption ◽  
Metal Insulator Metal ◽  
Index Sensitivity ◽  
Scattering Cross Sections

We theoretically investigate a multi-resonant plasmonic metamaterial perfect absorber operating between 600 and 950 nm wavelengths. The presented device generates 100% absorption at two resonance wavelengths and delivers an ultra-narrow band (sub-20 nm) and high quality factor (Q=44) resonance. The studied perfect absorber is a metal–insulator–metal configuration where a thin MgF2 spacer is sandwiched between an optically thick gold layer and uniformly patterned gold circular nanodisc antennas. The localized and propagating nature of the plasmonic resonances are characterized and confirmed theoretically. The origin of the perfect absorption is investigated using the impedance matching and critical coupling phenomenon. We calculate the effective impedance of the perfect absorber and confirm the matching with the free space impedance. We also investigate the scattering properties of the top antenna layer and confirm the minimized reflection at resonance wavelengths by calculating the absorption and scattering cross sections. The excitation of plasmonic resonances boost the near-field intensity by three orders of magnitude which enhances the interaction between the metamaterial surface and the incident energy. The refractive index sensitivity of the perfect absorber could go as high as S=500 nm/RIU. The presented optical characteristics make the proposed narrow-band multi-resonant perfect absorber a favorable platform for biosensing and contrast agent based bioimaging.

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