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A Facile Film-Nanoctahedron Assembly Route to Plasmonic Metamaterial Absorbers at Visible Frequencies
摘要： Plasmonic metamaterial absorbers (MAs) with broadband and near-perfect absorption properties in the visible region were successfully fabricated via a facile film-colloidal nanoparticle (NP) assembly method. In this approach, colloidal octahedral Au NPs were employed as the surface meta-atoms of MAs, while the nanoscale-thick SiO2 and Al films were used as the dielectric spacer and reflector respectively. It is worth noting that the Au nanoctahedron were randomly assembled onto the Al-SiO2 films, and no effort was made to precisely control their spatial arrangements. The optical characterization showed that the as-prepared MAs exhibited broadband high absorption (average absorptivity above 85%) within the whole visible spectrum for a broad range of incident angles (0°–60°). In particular, two polarization-independent near-perfect absorption peaks (absorptance above 99%) were recorded near 540 nm and 727 nm respectively. Moreover, the absorption properties of the MAs can be effectively controlled and tailored by varying the geometry (the thickness of the dielectric spacer and the surface coverages of the Au nanoctahedron). Electromagnetic simulations further demonstrated that enhanced Mie resonances and strong plasmonic coupling effects were critical for the designed MAs. This work here may provide an efficient and alternative route for the design of scalable visible light absorbers for applications such as solar cells, photothermalvoltaics, and biochemical sensors.
关键词： metamaterial absorbers,broadband and near-perfect absorption,aperiodic nanostructures,optical impedance matching,self-assembly
更新于2025-10-22 19:40:53
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Enhanced absorption of monolayer molybdenum disulfide (MoS2) using nanostructures with symmetrical cross resonator in the visible ranges
摘要： In order to enhance the absorption of monolayer molybdenum disulfide (MoS2), a novel nanostructure with symmetrical cross resonator based on MoS2 in the visible wavelength ranges has been proposed. At a resonant wavelength of 623 nm, the absorption of monolayer MoS2 in the absorption structure is as high as 82%, much higher than the bare MoS2 in the air. The electric field around monolayer MoS2 is enhanced by the guided mode resonance, thereby enhancing the absorption of monolayer MoS2 in the structure. The relevant parameters of the proposed structure are adjusted to achieve the tunability of the resonant wavelength in the visible ranges and the high-efficiency absorption of monolayer MoS2 in the structure, which is of great significance for the applications of MoS2-based optoelectronic devices.
关键词： Absorption,Monolayer MoS2,Perfect absorption structure,Resonance
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Hong Kong, China (2018.11.5-2018.11.9)] 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Designing thin-film metamaterials by tuning effective ENZ behavior
摘要： Using an effective refractive index calculation, we demonstrate the ability to efficiently tune epsilon-near-zero (ENZ) behavior within compact thin-film stacks. Results show the desired effect of broadening the reflectivity profile and improving absorption for an all-oxide ENZ metamaterial.
关键词： near-zero index,metamaterials,perfect absorption,plasmonic,thin film,ENZ tuning,effective index
更新于2025-09-23 15:22:29
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Planar hot-electron photodetector utilizing high refractive index MoS<sub>2</sub> in fabry-p??rot perfect absorber
摘要： Hot electron photodetection (HEPD) excited by surface plasmon can circumvent bandgap limitations, opening pathways for additional energy harvesting. However, the costly and time-consuming lithography and electron beam lithography-free hot electron photodetector based on the Fabry-Pérot resonance has long been a barrier for large-area and mass production of HEPD. In this paper, we proposed a planar and electron beam lithography-free hot electron photodetector based on the Fabry-Pérot resonance composed of Au/MoS2/Au cavity. The hot electron photodetector has a nanoscale thickness, high spectral tenability, and multicolour photoresponse in the near-infrared region due to the increased round-trip phase shift by using high refractive index MoS2. We predict that the photoresponsivity can achieve up to 23.6 mA/W when double cavities are integrated with the Fabry-Pérot cavity. The proposed hot electron photodetector that has a nanoscale thickness and planar stacking is a perfect candidate for large-area and mass production of HEPD.
关键词： Hot electron,photodetection,Molybdenum disulphide,Fabry-Pérot resonance,perfect absorption
更新于2025-09-23 15:21:01
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Dynamically tunable perfect absorption based on the phase transition of vanadium dioxide with aluminum hole arrays
摘要： Integrating plasmonic nanostructures with functional materials can further control over the optical resonant responses. A perfect absorber (PA) consisting of aluminum (Al) ring array intercalated with vanadium dioxide (VO2) disk is presented. The resonance wavelength of absorption peak can be tuned over a wide range in the visible (Vis) and near-infrared (NIR) regimes. The absorption peak shifts from 770 nm to 1336 nm while VO2 undergoes a structural transition from metallic phase (m-VO2) to insulator phase (i-VO2), resulting in a relative 73.5% wavelength shift. In addition, the absorption peak is strongly dependent on the height and radius of the ring disk as well as the period of lattice. Our work also suggests that the designed VO2-based absorber has the potential to overcome the di?culty in performing dynamically tunable resonances and near-unity absorbance with wide angle of incidence as well as weak polarization dependence.
关键词： Vanadium dioxide (VO2),Visible and near-infrared spectral,Phase change material,Perfect absorption
更新于2025-09-23 15:21:01
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Detailed Experiment-Theory Comparison of Mid-Infrared Metasurface Perfect Absorbers
摘要： Realisation of a perfect absorber A = 1 with transmittance and reflectance T = R = 0 by a thin metasurface is one of the hot topics in recent nanophotonics prompted by energy harvesting and sensor applications (A + R + T = 1 is the energy conservation). Here we tested the optical properties of over 400 structures of metal–insulator–metal (MIM) metasurfaces for a range of variation in thickness of insulator, diameter of a disc and intra-disc distance both experimentally and numerically. Conditions of a near perfect absorption A > 95% with simultaneously occurring anti-reflection property (R < 5%) was experimentally determined. Differences between the bulk vs. nano-thin film properties at mid-IR of the used materials can be of interest for plasmonic multi-metal alloys and high entropy metals.
关键词： mid infrared absorption,metasurface,perfect absorption
更新于2025-09-23 15:19:57
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Multi-spectral frequency selective mid-infrared microbolometers
摘要： Frequency selective detection of low energy photons is a scientific challenge using natural materials. A hypothetical surface which functions like a light funnel with very low thermal mass in order to enhance photon collection and suppress background thermal noise is the ideal solution to address both low temperature and frequency selective detection limitations of present detection systems. Here, we present a cavity-coupled quasi-three dimensional plasmonic crystal which induces impedance matching to the free space giving rise to extraordinary transmission through the sub-wavelength aperture array like a 'light funnel' in coupling low energy incident photons resulting in frequency selective perfect (~100%) absorption of the incident radiation and zero back reflection. The peak wavelength of absorption of the incident light is almost independent of the angle of incidence and remains within 20% of its maximum (100%) up to 45°. This perfect absorption results from the incident light-driven localized edge 'micro-plasma' currents on the lossy metallic surfaces. The wide-angle light funneling is validated with experimental measurements. Further, a super-lattice based electronic biasing circuit converts the absorbed narrow linewidth (Δλ/λ ~0.075) photon energy inside the sub-wavelength thick film (< λ/100) to voltage output with high signal to noise ratio close to the theoretical limit. Such artificial plasmonic surfaces enable flexible scaling of light funneling response to any wavelength range by simple dimensional changes paving the path towards room temperature frequency selective low energy photon detection.
关键词： microbolometers,plasmonic crystal,light funnel,perfect absorption,room temperature detection,mid-infrared,frequency selective detection
更新于2025-09-19 17:15:36
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Plasmene Metasurface Absorbers: Electromagnetic Hot Spots and Hot Carriers
摘要： Light-matter interactions are extremely important as they sustain life on Earth and can be tailored for diverse applications in areas such as solar energy conversion, chemical sensing, and information storage. One key process of these interactions is the absorption of photons. We demonstrate a novel material capable of absorbing up to 98% of incident visible light. The material comprises a thin sheet of a tightly-packed two-dimensional lattice of metal nanoparticles, called plasmene, supported by a thin (sub-wavelength) dielectric film deposited on top of a mirror. We demonstrate how the resulting metasurface absorbers are useful in surface-enhanced spectroscopy and in the generation of plasmonic hot carriers. These structures hold great promise for applications in structural color, sensing and photocatalysis.
关键词： plasmene,optical magnetic mode,hot carriers,perfect absorption,metasurfaces,Plasmonics
更新于2025-09-19 17:15:36
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A Bilayer Plasmonic Metasurface for Polarizationa??Insensitive Bidirectional Perfect Absorption
摘要： The implementation of perfect absorption of optical waves in artificial nanostructures has attracted tremendous attention among the scientific community. Traditional approaches based on metamaterials can only absorb optical waves in one direction while reflecting optical waves in the other direction. Here, a polarization-insensitive bidirectional perfect absorber that is composed of bilayer gold nano disks embedded into a silicon nitride substrate is demonstrated. The bidirectional perfect absorption in the proposed bilayer metasurface, which is irrelevant to the coherent of optical waves, is attributed to the multiple reflections and interference of optical waves in the bilayer structures. The proposed perfect absorber shall boost its applications in optical anti-counterfeiting, integrated photodetectors, and solar thermal applications.
关键词： alignment-free,few-layer metasurfaces,polarization-insensitive,bidirectional perfect absorption
更新于2025-09-16 10:30:52
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Dynamic metasurface based cavity structures for enhanced absorption and phase modulation
摘要： Metasurface based optical cavity structures consist of a metallic metasurface realized on top of a dielectric slab backed with a metal plane. Such structures have been employed in the design of optical devices such as flat lenses, wave plates and holograms at frequencies from microwave to mid-infrared. Recently, such structures with dynamically reconfigurable optical characteristics have been explored for electrically tunable optical absorption and reflection phase modulation. To date, absorption modulation and phase modulation have been realized with large insertion loss. In this work, we employ an analytical approach based on transmission line theory where the metasurface is represented by a surface admittance. We extend the above approach for the design and analysis of under and over coupled resonance regimes in metasurface cavity structure. This enables a mutual design of cavity thickness and individual metasurface for large amplitude or phase modulation. A dynamic metasurface based optical cavity is experimentally demonstrated at THz frequencies where the dynamic metasurface consists of metallic resonators embedded with thin film vanadium dioxide patches. By driving insulator to metal transition in vanadium dioxide, the THz optical response of the metasurface based cavity structure is modulated. The fabricated device exhibits perfect absorption modulation and reflection phase modulation up to 180°. The reported results demonstrate the potential of such structures for realizing novel devices such as tunable holograms, high-efficiency modulators and frequency tunable filters at THz. The analytical approach presented here can be applied for analysis and design of metasurface cavity structures based on other material systems at frequencies ranging from THz to mid-infrared.
关键词： Terahertz,Phase modulator,Dynamic metasurface,Perfect absorption modulator,Metasurface optical cavity
更新于2025-09-10 09:29:36