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Switchable Complementary Diamond-ring-shaped Metasurface for Radome Application
摘要： Microwave radomes exhibiting bandpass behavior are highly desirable for antenna systems. However, most of these radomes are not frequency switchable owing to their fixed structures. Here, a switchable metasurface based on complementary diamond-ring-shaped resonators is proposed for radomes. The microwave properties of the metasurface are investigated via simulations and experiments at X-band. By adjusting the rotation angle θ from 0° to 90°, the bandpass frequency is switched from 11.0 GHz to 9.4 GHz. Two passbands appear for 0° < θ < 90°. In addition, the bandwidth can also be tuned by adjusting the rotation angle. This approach paves the way for designing switchable microwave radomes.
关键词： Switchable,Complementary diamond-ring-shaped resonator,Radomes,Metasurfaces
更新于2025-09-23 15:21:01
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Lattice effect in Mie-resonant dielectric nanoparticle array under oblique light incidence
摘要： Ultra-thin optical structures, known as metasurfaces, have shown promising light controlling capability at the nanoscale. In this paper, we study their particular case, a periodic array of high-refractive-index nanoparticles with electric and magnetic resonances. The main result of the work is a numerical demonstration that the lattice effect in the periodic arrangement of nanoparticles changes the resonance position even if the resonances are above the diffraction wavelength (Rayleigh anomaly). We show that the disk resonance changes can be achieved not only by varying periods of the array under normal light incidence but also by changing the incident angle.
关键词： metasurfaces,Rayleigh anomaly,electric and magnetic resonances,high-refractive-index nanoparticles,lattice effect
更新于2025-09-23 15:21:01
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Ultrawideband Spina??Decoupled Coding Metasurface for Independent Duala??Channel Wavefront Tailoring
摘要： Achieving distinct functionalities for electromagnetic (EM) waves with opposite handedness in a broad frequency range is highly desirable and essential for modern wireless communications and radar stealth. However, available functional meta-devices still suffer from the issues of locked functionalities or spin-decoupled properties but with limited bandwidth. Here, a spin-decoupled coding metasurface is presented for achieving independently spin-controlled functionalities with high efficiency in an ultrawide frequency band. By synthesizing the Jones matrix, it is predicted that two half-wave plates with a phase difference of 90° can form a 1-bit coding metasurface operating for orthogonal spins independently. As proofs of concept, two meta-devices are implemented by the metasurface in the microwave region. The first meta-device performs as a spin-decoupled beam deflector while the second one shows an ability to generate spin-decoupled multi-beams carrying desired orbital angular momentums. Both of the designed meta-devices can operate in the whole band of 7.5–18.5 GHz (with relative bandwidth of 80%), which, to the best knowledge, is so far the broadest bandwidth that can be achieved by spin-decoupled metasurfaces. This may trigger interest and open opportunities for advanced functional meta-devices in practical applications, for example, multichannel metasurface antennas, or multifunctional low-scattering devices in microwave region.
关键词： coding metasurfaces,ultrawide frequency band,dual-channel wavefront,spin-decoupled metasurfaces
更新于2025-09-23 15:19:57
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All-carbon THz components based on laser-treated diamond
摘要： We report on fs laser structuring and graphitization of diamond and experimental characterization of its THz response. A full characterization of graphitized, conductive layer generated by laser irradiation is carried out by performing scanning-electron microscopy, Raman spectroscopy and electrical measurements. The transmittance of the laser textured diamond samples, both with the graphitic overlayer and after selective oxidizing etching, is analyzed in the (0.25 ÷ 6.0) THz spectral range. A significant selective absorption of the graphitized overlayer towards polarized THz radiation is demonstrated, which is associated to the formation of graphitic laser induced periodic surface structures. This anisotropy allows conceiving compact passive metasurfaces based on conductive/dielectric patterns on the diamond plate surface for the development of robust, lightweight and broadband THz optical components.
关键词： graphitic laser induced periodic surface structures,graphitization,electrical measurements,fs laser structuring,THz response,transmittance,THz optical components,polarized THz radiation,conductive layer,diamond,Raman spectroscopy,metasurfaces
更新于2025-09-23 15:19:57
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Electro-optical Amplitude and Phase Modulators Based on Tunable Guided-Mode Resonance Effect
摘要： Here, electrically tunable amplitude and phase modulators are designed by the hybridization of indium tin oxide (ITO) into a guided-mode resonance mirror (so-called GMRM) which consists of a high-index silicon (Si) nanograting placed on top of a Si guiding core followed by a silicon-dioxide optical buffer layer and a highly reflective substrate. The physical mechanism is based on the intriguing optical characteristics of GMRMs and integration of a dual-gated ITO with the capability of charge carrier modulation into the Si nanograting. A gate-tunable amplitude modulator with a modulation depth as high as ≈0.80 is realized by careful selection of structural parameters, excitation of a strongly coupled guided-mode resonance, and modifying the external bias voltage. This design can also be adjusted only by changing the thickness of its optical buffer layer and moderating the strength of the guided-mode resonance to serve as an efficient active phase modulator. The phase variation of ≈210° and relatively high reflection amplitude in 0.45-0.6 range are accomplished when the applied bias voltage alters from -15 V to +24 V. This reflection phase tuning mainly originates from the carrier depletion and accumulation inside the incorporated 5 nm-thick ITO layer. The accurate modeling and numerical calculation of optical response of the proposed unit cell for different applied external voltages are carried out through linking the electrostatics device physics model and rigorous coupled wave analysis (RCWA) optical simulation. The design rules and physical principles behind the dual-gated ITO-integrated GMRM unit cell are discussed in-depth by investigation of the structural parameters, the nature of supported resonances, and voltage-dependent effects of inhomogeneous carrier distributions in both ITO and Si layers. The electrical addressability and individual control over pixelated subwavelength unit cells provide the opportunity for realizing an actively reconfigurable metasurface with the desired gradient phase delay.
关键词： metasurfaces,phase and amplitude modulators,electro-optical materials,silicon,guided-mode resonance,indium tin oxide,All-dielectric
更新于2025-09-23 15:19:57
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Infrared-controlled programmable metasurface
摘要： Programmable metasurface enables controlling electromagnetic (EM) waves in real time. By programming the states of active device embedded in metasurface element, the EM properties of the digital metasurface can be changed quickly without redesigning their structures. However, large numbers of long-distance wires are required to connect the programmable metasurface to provide the coded signals from field programmable gate array (FPGA) when controlling the metasurface at a long distance, which is complicated and inconvenient. Here, we propose an infrared-controlled programmable metasurface that can be programmed remotely. The infrared transceiver is able to switch the coding sequences stored in the FPGA controller, thus controlling the voltage on the varactors integrated in the metasurface. Experiment is performed at microwave frequencies, and the measured results verify that the scattering beams of the metasurface sample can be changed remotely by using infrared ray. The proposed infrared-controlled programmable metasurface opens up avenues for constructing a new class of remotely-tuning dynamic metasurfaces.
关键词： remotely-tuning,beam splitting,infrared-controlled programmable metasurfaces,beam scanning
更新于2025-09-23 15:19:57
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Direct and High-Throughput Fabrication of Mie-Resonant Metasurfaces <i>via</i> Single-Pulse Laser Interference
摘要： High-index dielectric metasurfaces featuring Mie-type electric and magnetic resonances have been of a great interest in a variety of applications such as imaging, sensing, photovoltaics and others, which led to the necessity of an efficient large-scale fabrication technique. To address this, here we demonstrate the use of single-pulse laser interference for direct patterning of an amorphous silicon film into an array of Mie resonators with few hundred nanometers in diameter. The proposed technique is based on laser-interference-induced dewetting. A precise control of the laser pulse energy enables the fabrication of ordered dielectric metasurfaces in areas spanning tens of micrometers and consisting of thousands of hemispherical nanoparticles with a single laser shot. The fabricated nanoparticles exhibit a wavelength-dependent optical response with a strong electric dipole signature. Variation of the pre-deposited silicon film thickness allows tailoring of the resonances in the targeted visible and infrared spectral ranges. Such direct and high-throughput fabrication is a step towards a simple realization of spatially invariant metasurface-based devices.
关键词： direct laser interference patterning,metasurfaces,laser-matter interaction,dielectric nanostructures,silicon resonators,multi-beam interference
更新于2025-09-23 15:19:57
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Polarization-Controlled Dual-Programmable Metasurfaces
摘要： Programmable metasurfaces allow dynamic and real-time control of electromagnetic (EM) waves in subwavelength resolution, holding extraordinary potentials to establish meta-systems. Achieving independent and real-time controls of orthogonally-polarized EM waves via the programmable metasurface is attractive for many applications, but remains considerably challenging. Here, a polarization-controlled dual-programmable metasurface (PDPM) with modular control circuits is proposed, which enables a dibit encoding capability in modifying the phase profiles of x- and y-polarized waves individually. The constructed extended interface circuit is able to extend the number of control interfaces from a field programmable gate array by orders of magnitude and also possesses memory function, which enhance hugely the rewritability, scalability, reliability, and stability of PDPM. As a proof-of-concept, a wave-based exclusive-OR logic gate platform for spin control of circularly-polarized waves, a fixed-frequency wide-angle dual-beam scanning system, and a dual-polarized shared-aperture antenna are demonstrated using a single PDPM. The proposed PDPM opens up avenues for realizing more advanced and integrated multifunctional devices and systems that have two independent polarization-controlled signal channels, which may find many applications in future-oriented intelligent communication, imaging, and computing technologies.
关键词： orthogonally-polarized electromagnetic waves,beam controls,digital logic platforms,modular control circuits,dual-programmable metasurfaces
更新于2025-09-23 15:19:57
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Switchable active phase modulation and holography encryption based on hybrid metasurfaces
摘要： Metasurfaces are planar devices containing delicately designed nanoantenna or resonator arrays that allow for beam shaping, super resolution imaging, and holography. Hybrid metasurface – by integrating with tunable materials such as two-dimensional materials and phase change materials (PCMs) – provides a potential platform for active modulation of wavefronts. Specifically, PCMs can flexibly switch between crystalline and amorphous states with nonvolatile property under external stimuli and provide a large refractive permittivity contrast. Using metasurfaces based on PCM to manipulate wavefronts may provide new opportunities for switchable functionalities. Here, we propose two types of metasurface devices based on whole PCM films to realize switchable holography and simultaneous phase and interference encryption. This feature can be used to encrypt information in a switched state and store camouflage information in the other state by simply applying external thermal stimuli to the entire metasurface. This method can be applied in areas such as beam shaping, optical encryption, and anti-counterfeiting.
关键词： active modulation,holographic encryption,hybrid metasurfaces
更新于2025-09-23 15:19:57
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Nonlinear optics with resonant metasurfaces
摘要： The field of nonlinear optics is a well-established discipline that relies on macroscopic media and employs propagation distances longer than a wavelength of light. Recent progress with electromagnetic metamaterials has allowed for the expansion of this field into new directions of new phenomena and novel functionalities. In particular, nonlinear effects in thin, artificially structured materials such as metasurfaces do not rely on phase-matching conditions and symmetry-related selection rules of natural materials; they may be substantially enhanced by strong local and collective resonances of fields inside the metasurface nanostructures. Consequently, nonlinear processes may extend beyond simple harmonic generation and spectral broadening due to electronic nonlinearities. This article provides a brief review of basic concepts and recent results in the field of nonlinear optical metasurfaces.
关键词： frequency conversion,high-harmonic generation,resonances,metasurfaces,nonlinear optics
更新于2025-09-23 15:19:57