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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Tri-band Linear to Circular Polarization Converter based on Transmissive Metasurfaces
摘要： Multi-band operation for terahertz wireless systems is a challenging problem. We propose a tri-band linear to circular polarization converter in the terahertz regime using metasurfaces in transmission modes. The converter is composed of bi-layered metasurfaces separated by a dielectric spacer. Three bands (0.54-0.804, 1.904-2.476, and 2.96-3.884 THz) of linear to circular polarization conversion (LCPC) are achieved due to the superposition of the two transmitted components with a near 90° phase difference. Idea is verified by HFSS and paves a way to the design of multi-band transmissive linear to circular polarization converter.
关键词： linear to circular polarization converter,transmission modes,metasurfaces,terahertz,Multi-band operation
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Second-Harmonic Generation in Monolithic Lithium Niobate Metasurfaces
摘要： Second harmonic generation (SHG) in nonlinear metasurfaces has proven as a versatile tool for novel ultra-thin light sources with engineered spatial wavefronts. However, the availability of second-order nonlinear materials suitable for fabrication of such metasurfaces has so far been mainly limited to III-V semiconductors (e.g. GaAs, AlGaAs, GaP). Such systems have a limited transparency range and unusual off-diagonal second-order susceptibility tensors. These constraints have driven the search for new material platforms, including lithium niobate as one of the most promising nonlinear materials. Various approaches, such as plasmonic cavities [1], bottom-up techniques [2] and lithium niobate on insulator [3], have been recently explored, however with limited applicability. Here we propose a new design concept for second-order nonlinear metasurfaces on a monolithic substrate, which is not limited by the availability of thin crystalline films and can be applied to any non-centrosymmetric material. Our approach enables blue SHG from a monolithic lithium niobate metasurface with a conversion efficiency above 10?5 using 1 GW/cm2 pump intensity, opening new opportunities for practical designs of nonlinear metasurfaces.
关键词： second harmonic generation,monolithic substrate,Mie-type resonances,lithium niobate,nonlinear metasurfaces
更新于2025-09-16 10:30:52
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Towards Efficient Nonlinear Plasmonic Metasurfaces
摘要： Nonlinear processes are important in many fields of photonics ranging from biomedical imaging to ultrashort pulse generation. Progress in nanophotonics and metamaterials has created a growing demand for nanoscale nonlinear optical components. However, it is difficult to answer this demand by using traditional materials motivating the search for alternatives approaches. Nonlinear plasmonics has emerged as a viable solution for enabling efficient and nanoscale nonlinear optics. Despite steady progress, so far achieved conversion efficiencies of metamaterials have not yet rivalled conventional nonlinear materials. Here, we discuss our recent progress in development of efficient nonlinear plasmonic metamaterials. Focus is on metasurfaces utilizing collective responses known as surface lattice resonances, which can be used to dramatically boost nonlinear responses of metasurfaces.
关键词： nonlinear metamaterials,surface lattice resonances,metasurfaces,frequency conversion
更新于2025-09-16 10:30:52
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Nanoscale characterization of photonic metasurface made of lens-like SiGe Mie-resonators formed on Si (100) substrate
摘要： Submicrometer-sized high-index Mie resonators attract significant interest in photonic applications due to their capabilities to manipulate light. 2-dimensional metamaterials or metasurfaces consisting of arrays of such resonators on a device surface can be used in the flat optics, sensors, and other applications. Here, we report on the comprehensive nanoscale characterization and optical properties of nearly regular SiGe Mie resonator arrays on a Si surface fabricated using a simple and low-cost method. We achieved control on the surface morphology by depositing Ge on the Si(100) surface at elevated temperatures 890–960 °C and obtained arrays of submicrometer/micrometer low-Ge-content SiGe lenslike islands via dewetting when the Ge content was >4%. At the lower Ge content, we observed the formation of a continuous SiGe film via wetting. We used Raman microscopy not only for the Ge content and stress control but also for studying photonic properties of the islands and their coupling with the Si substrate. In contrast to the elastic light scattering, we clearly distinguished visible light Raman signals from the islands themselves and from the substrate areas under the islands enhanced compared to the signal from the open substrate. Calculation of the light electric field distribution in the islands and the substrate demonstrate how the islands trap the light and forward it into the high-index substrate. This explains the island-induced reflection suppression and Si substrate Raman enhancement, which we observe experimentally. Such an SiGe-island array is a promising metasurface for the improvement of Si photosensors and solar-energy device performance.
关键词： SiGe,metasurfaces,photonic properties,Mie resonators,Raman microscopy
更新于2025-09-16 10:30:52
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Fast Analysis of Metasurfaces through Temporal Coupled-mode Theory
摘要： In this article, a rigorous temporal coupled-mode theory (CMT) formalism is developed, to analyze metasurface (MTS)-based structures. Such MTSs are generally rather complex, requiring extensive, full-wave simulations. To facilitate their design and minimize the associated computational demand, the CMT solves a small linear system of equations, fed by the results of certain much simpler and less time- and memory-consuming eigenvalue problems. The proposed method is versatile and offers an initial, valuable estimation of the structure’s frequency response, which may be used as a guideline for the ?nal MTS ?ne tuning. As proof of concept, split-ring resonator (SRR) MTSs coupled to microstrip lines are analyzed, and their response is compared with the full-wave ?nite-element method (FEM) results.
关键词： Coupled-mode analysis,planar arrays,metasurfaces (MTSs),electromagnetic metamaterials
更新于2025-09-16 10:30:52
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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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Hybrid plasmonic metasurfaces
摘要： Plasmonic metasurfaces based on ensembles of distributed metallic nanostructures can absorb, scatter, and in other ways shape light at the nanoscale. Forming hybrid plasmonic metasurfaces by combination with other materials opens up for new research directions and novel applications. This perspective highlights some of the recent advancements in this vibrant research field. Particular emphasis is put on hybrid plasmonic metasurfaces comprising organic materials and on concepts related to switchable surfaces, light-to-heat conversion, and hybridized light-matter states based on strong coupling.
关键词： strong coupling,hybrid plasmonic metasurfaces,organic materials,light-to-heat conversion,switchable surfaces
更新于2025-09-16 10:30:52
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Dual-band and ultra-broadband photonic spin-orbit interaction for electromagnetic shaping based on single-layer silicon metasurfaces
摘要： Achieving electromagnetic wave scattering manipulation in the multispectral and broad operation band has been a long pursuit in stealth applications. Here, we present an approach by using single-layer metasurfaces composed of space-variant amorphous silicon ridges tiled on a metallic mirror to generate high-efficiency dual-band and ultra-wideband photonic spin-orbit interaction and geometric phase. Two scattering engineered metasurfaces have been designed to reduce specular reflection; the first one can suppress both specular reflectances at 1.05–1.08 μm and 5–12 μm below 10%. The second one is designed for an ultra-broadband of 4.6–14 μm, which is actually implemented by cleverly connecting two bands of 4.6–6.1 μm and 6.1–14 μm. Furthermore, the presented structures exhibit low thermal emission at the same time due to the low absorption loss of silicon in the infrared spectrum, which can be regarded as an achievement of laser–infrared compatible camouflage. We believe the proposed strategy may open a new route to implement multispectral electromagnetic modulation and multiphysical engineering applications.
关键词： photonic spin-orbit interaction,stealth applications,geometric phase,metasurfaces,electromagnetic shaping
更新于2025-09-16 10:30:52
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Terahertz sensing of 7?nm dielectric film with bound states in the continuum metasurfaces
摘要： The fingerprint spectral response of several materials with terahertz electromagnetic radiation indicates that terahertz technology is an effective tool for sensing applications. However, sensing few nanometer thin-films of dielectrics with much longer terahertz waves (1 THz = 0.3 mm) is challenging. Here, we demonstrate a quasibound state in the continuum (BIC) resonance for sensing of a nanometer scale thin analyte deposited on a flexible metasurface. The large sensitivity originates from the strong local field confinement of the quasi-BIC Fano resonance state and extremely low absorption loss of a low-index cyclic olefin copolymer substrate. A minimum thickness of 7 nm thin-film of germanium is sensed on the metasurface, which corresponds to a deep subwavelength scale of k/43 000, where k is the resonance wavelength. The low-loss, flexible, and large mechanical strength of the quasi-BIC microstructured metamaterial sensor could be an ideal platform for developing ultrasensitive wearable terahertz sensors.
关键词： metasurfaces,bound states in the continuum,sensing,terahertz,dielectric film
更新于2025-09-16 10:30:52
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Tunable multimodal magnetoplasmonic metasurfaces
摘要： The spectrally controllable enhancement of the transverse magneto-optical Kerr effect is realized in 2D hybrid metal-dielectric magnetoplasmonic metasurfaces. The light diffracted at different interfaces allows one to manipulate light phase in the condition of plasmonic and waveguiding resonance excitation controllable via the azimuthal angle. The multimodal nature of the system provides the flexible tunability of its magneto-optical response.
关键词： azimuthal angle,magneto-optical Kerr effect,magnetoplasmonic metasurfaces,plasmonic resonance,waveguiding resonance
更新于2025-09-16 10:30:52