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Hybrid Metasurfaces for Infrared-Multiband Radar Stealth-Compatible Materials Applications
摘要： The compatible stealth functionality in the infrared (IR) and radar wave bands is the most important research topic in the field of stealth material technology. Here, a new hybrid metasurface (HMS) for infrared-multiband radar stealth-compatible materials was proposed and studied. Two specifically designed metasurface layers that can control the infrared emission and microwave absorption were combined to realize radar and IR bi-stealth. The simulated and experimental results show that the HMS has five strong absorption peaks at f1=6.35, f2=8.38, f3=12.10, f4=15.37 and f5=18.05 GHz. In addition, the emissivity of the proposed HMS is less than 0.32 from 3 to 14 μm and shows low emissivity characteristics in the infrared band. These results demonstrate that the proposal has practical application to multispectral stealth technology.
关键词： infrared-radar stealth-compatible,metasurfaces,low emission
更新于2025-09-19 17:13:59
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Magnesium-Based Metasurfaces for Dual-Function Switching between Dynamic Holography and Dynamic Color Display
摘要： Metasurface-based color display and holography have greatly advanced the state of the art display technologies. To further enrich the metasurface functionalities, recently a lot of research endeavors have been made to combine these two display functions within a single device. However, so far such metasurfaces have remained static and lack tunability once the devices are fabricated. In this work, we demonstrate a dynamic dual-function metasurface device at visible frequencies. It allows for switching between dynamic holography and dynamic color display, taking advantage of the reversible phase-transition of magnesium through hydrogenation and dehydrogenation. Spatially-arranged stepwise nanocavity pixels are employed to accurately control the amplitude and phase of light, enabling the generation of high-quality color prints and holograms. Our work represents a paradigm towards compact and multifunctional optical elements for future display technologies.
关键词： magnesium,metasurfaces,color display,holography,multifunction
更新于2025-09-19 17:13:59
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Dielectrics for Terahertz Metasurfaces: Material Selection and Fabrication Techniques
摘要： Manipulation of terahertz radiation opens new opportunities that underpin application areas in communication, security, material sensing, and characterization. Metasurfaces employed for terahertz manipulation of phase, amplitude, or polarization of terahertz waves have limitations in radiation efficiency which is attributed to losses in the materials constituting the devices. Metallic resonators-based terahertz devices suffer from high ohmic losses, while dielectric substrates and spacers with high relative permittivity and loss tangent also reduce bandwidth and efficiency. To overcome these issues, a proper choice of low loss and low relative permittivity dielectric layers and substrates can improve field confinement and reduce dissipation. Alternatively, replacing metallic resonators with a moderate relative permittivity dielectric material that supports cavity mode resonances also reduces dissipation due to the absence of conduction current. Herein, an overview of dielectric materials employed as spacers and dielectric resonators is provided, and the fabrication methods employed to realize these devices at the terahertz frequency range are also presented. Material selection guidelines, material-specific and application-specific fabrication quality metrics are outlined, and new techniques are proposed.
关键词： metasurfaces,dielectric spacers,dielectric resonators,low loss dielectrics,terahertz devices
更新于2025-09-19 17:13:59
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Bound States in the Continuum in Magnetophotonic Metasurfaces
摘要： We analyze the enhancement mechanisms of magneto-optical effects in all-dielectric metasurfaces caused by the bound state in the continuum resonance. In a structure under study, a square lattice of bismuth substituted yttrium iron garnet nanodisks with an air hole displaced away from the disk axis, magneto-optical polarization and intensity effects reach 0.7° and 22%, respectively.
关键词： bound state in the continuum,magneto-optical effects,all-dielectric metasurfaces,bismuth substituted yttrium iron garnet
更新于2025-09-19 17:13:59
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Toroidal metasurfaces integrated with microfluidic for terahertz refractive index sensing
摘要： A terahertz refractive index sensor consisting of toroidal dipole resonance metasurface integrated with microfluidic channel is proposed. The excitation of toroidal dipole resonance in this metasurface and the localized electromagnetic field enhancement in microfluidic channel are investigated comprehensively. Numerical results show that the calculated quality factor and the corresponding figure of merit can reach 1103 and 244, much higher than previously reported terahertz metamaterials sensors. Moreover, the refractive index sensing capabilities of non-polar and polar liquids are also investigated, which demonstrate the resonant frequency shift does not depend on the losses of analytes and show this device can be used for sensing various materials, including highly absorptive materials. This proposed structure can be extended to work in other frequency regions and has potential applications in high performance gases, liquids and biological materials sensing.
关键词： toroidal dipole,metasurfaces,microfluidic,refractive index sensing,terahertz
更新于2025-09-19 17:13:59
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Tunable Bound States in the Continuum in All-Dielectric Terahertz Metasurfaces
摘要： In this paper, a tunable terahertz dielectric metasurfaces consisting of split gap bars in the unit cell is proposed and theoretically demonstrated, where the sharp high-quality Fano resonance can be achieved through excitation of quasi-bound states in the continuum (quasi-BIC) by breaking in-plane symmetry of the unit cell structure. With the structural asymmetry parameter decreasing and vanishing, the calculated eigenmodes spectra demonstrate the resonance changes from Fano to symmetry-protected BIC mode, and the radiative quality factors obey the inverse square law. Moreover, combining with graphene monolayer and strontium titanate materials, the quasi-BIC Fano resonance can be tuned independently, where the resonance amplitude can be tuned by adjusting the Fermi level of graphene and the resonance frequency can be tuned by controlling the temperature of strontium titanate materials. The proposed structure has numerous potential applications on tunable devices including modulators, switches, and sensors.
关键词： graphene,tunable,quasi-bound states in the continuum,terahertz,dielectric metasurfaces
更新于2025-09-19 17:13:59
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Dual toroidal dipole resonances in a planar terahertz flexible metasurfaces
摘要： We proposed and fabricated planar dual toroidal dipole flexible metasurfaces at terahertz frequencies, and the units cell consists of two asymmetric J-shaped metallic ring resonators fabricated on the mylar medium. Measured and simulated results show that phase difference caused by the asymmetry of the metasurfaces in time and space lead to two strong toroidal dipole resonances in the transmission spectrum. The classical Fano resonance model is applied to the fitting of transmission spectrum, and the good coincidence reveals the metasurfaces resonant coupling mechanism. The resonances of metasurfaces are very sensitive to the dimensional parameters of the unit cell. The development of the sensitive dual-band planar terahertz toroidal dipole metasurfaces will promote the actual implementation of terahertz functional devices.
关键词： toroidal dipole,terahertz,metasurfaces
更新于2025-09-19 17:13:59
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Practical Chromatic Aberration Correction in Virtual Reality Displays Enabled by Cost‐Effective Ultra‐Broadband Liquid Crystal Polymer Lenses
摘要： Chromatic aberration (CA) is a critical issue in immersive virtual reality displays. The current digital compensation method can reduce the CA by pre-processing the image contents but at the cost of extra memory space, processing time, and power consumption. Moreover, it is not possible to digitally compensate the CA within each color channel. Here, a practical optical approach is presented to correct the CAs, including the sub-channel ones, in the virtual reality system, whose functionality is verified by both ray-tracing analysis and experimental results. In this device, a compact ultra-broadband Pancharatnam-Berry phase lens (PBL) with complex axial molecular structure is fabricated and then hybridized with a refractive Fresnel lens. Due to their opposite chromatic dispersion, the system’s CA is significantly reduced. To eliminate ghost image from the zero-order leakage of PBL, a broadband circular polarizer is implemented to block the stray light. As a result, clear image within the entire 100° field-of-view is achieved. The proposed large-size cost-efficient broadband wide-view flat optics can practically benefit not only virtual reality displays but also general imaging systems for practical applications and scientific research.
关键词： metasurfaces,planar lenses,virtual reality,liquid crystal polymers,chromatic aberration
更新于2025-09-19 17:13:59
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Scale Law of Far-Field Thermal Radiation from Plasmonic Metasurfaces
摘要： Although metamaterials or metasurfaces consisting of patterned subwavelength structures have been widely employed for thermal emission control, the collective behavior of the emitter array in a metasurface still remains unclear. Here, based on the quasinormal mode theory, we derive a new scale law to elucidate the far-field thermal emission from a metasurface composed of densely packed plasmonic nanoemitters. The tight binding method is used to approximate the collective resonant mode of the emitter array. Because of in-phase near-field interaction, the thermal radiation from a single emitter in a metasurface is suppressed by its adjacent emitters. We find that the overall far-field thermal radiation from a metasurface can be either positively or negatively correlated with the packing density of the emitters, depending on the mode properties of the single emitter. This new scale law thus serves as a general guideline for designing metasurfaces with desired thermal emission properties.
关键词： thermal radiation,plasmonic metasurfaces,quasinormal mode theory,tight binding method
更新于2025-09-19 17:13:59
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Broadband and highly efficient polarization conversion in infrared region using plasmonic metasurfaces
摘要： We propose two categories of broadband, high-efficiency reflective wave plates operating in the infrared region. The first one is a half-wave plate (HWP) composed of single L-shaped antennas, and the second one is a quarter-wave plate (QWP) composed of double L-shaped antennas. In contrast to the conventional wave plate, the proposed QWP is a simple combination of two HWPs. We theoretically analyze the feasibility of the design and simulate the conversion efficiency. The proposed HWP and QWP are highly efficient with bandwidths of 1670–2791 nm and 1592–3867 nm, respectively. The novel design may be beneficial for the implementation of polarization conversion devices.
关键词： Metasurfaces,Infrared region,Polarization converter
更新于2025-09-19 17:13:59