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Electron quantum metamaterials in van der Waals heterostructures
摘要： In recent decades, scientists have developed the means to engineer synthetic periodic arrays with feature sizes below the wavelength of light. When such features are appropriately structured, electromagnetic radiation can be manipulated in unusual ways, resulting in optical metamaterials whose function is directly controlled through nanoscale structure. Nature, too, has adopted such techniques—for example in the unique colouring of butterfly wings—to manipulate photons as they propagate through nanoscale periodic assemblies. In this Perspective, we highlight the intriguing potential of designer structuring of electronic matter at scales at and below the electron wavelength, which affords a new range of synthetic quantum metamaterials with unconventional responses. Driven by experimental developments in stacking atomically layered heterostructures—such as mechanical pick-up/transfer assembly—atomic-scale registrations and structures can be readily tuned over distances smaller than characteristic electronic length scales (such as the electron wavelength, screening length and electron mean free path). Yet electronic metamaterials promise far richer categories of behaviour than those found in conventional optical metamaterial technologies. This is because, unlike photons, which scarcely interact with each other, electrons in subwavelength-structured metamaterials are charged and strongly interact. As a result, an enormous variety of emergent phenomena can be expected and radically new classes of interacting quantum metamaterials designed.
关键词： van der Waals heterostructures,nanoscale structure,electronic matter,electron quantum metamaterials,optical metamaterials
更新于2025-09-23 15:21:01
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Sierpi??ski Fractals as Plasmonic Metastructures for Second-Harmonic Generation
摘要： Metallic Sierpiński fractal metastructures made of gold nanoprisms that exhibit compatibility for both surface-enhanced Raman spectroscopy and second-harmonic generation have been prepared by electron-beam lithography. A sequential series of Sierpiński patterns were investigated up to the eighth-order generation. The presence of localized surface plasmon modes in the visible spectral range is due to the arrangement of the individual triangles forming the Sierpiński geometry, and was first exploited for surface-enhanced Raman measurements after functionalization of the plasmonic platform with p-Nitrothiophenol. Due to the non-centrosymmetric arrangement of the individual nanoprisms within the Sierpiński pattern, second-harmonic generation (SHG) microscopy measurements were conducted to evaluate the second-order nonlinear optical activity and its relationship to the spatial distributions of electromagnetic enhancement over the surface of the metastructure. Functionalization of the surface with molecules with an electron withdrawing group appears to further enhance the surface SHG signal.
关键词： Metamaterials,Plasmonics,Fractal plasmonics,Surface-enhanced Raman,Second-harmonic generation
更新于2025-09-23 15:21:01
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Gap Plasmon of Virus-Templated Biohybrid Nanostructures Uplifting the Performance of Organic Optoelectronic Devices
摘要： Plasmonic nanostructures, which exhibit prominent localized surface plasmon resonance (LSPR) properties, are highly desirable for organic solar cells (OSC) and organic light-emitting diode (OLED) devices. In the present work, novel plasmonic bio-nanostructures are successfully synthesized via the self-densification of silver (Ag) and gold (Au) metallic nanoparticles (NPs) onto a genetically engineered M13 bacteriophage template. Owing to the unique charge selectivity of the peptide receptors on the M13 bacteriophage, the metallic NPs can be directly anchored onto the bacteriophage through charge-driven interactions without binder/surfactant. The resulting Ag/AuNP-M13 bio-nanostructures display extraordinary gap-plasmon effect as well as tremendously enhanced LSPR properties than the randomly dispersed Ag/Au NPs. The incorporation of Ag/AuNP-M13 bio-nanostructures tremendously improves the performance of both OSC and OLED devices. Specifically, a power conversion efficiency increment of 15.5% is recorded for the phage-modified OSCs; whereas an external quantum efficiency increment of 22.6% is achieved for the phage-modified OLEDs. Based on this environmentally benign virus-template approach, various plasmonic/photonic bio-nanostructures can be designed for diverse device applications.
关键词： field-enhancement,optoelectronics,M13 bacteriophage,metamaterials,self-assembly,gap-plasmon effect
更新于2025-09-23 15:21:01
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Saturable plasmonic metasurfaces for laser mode locking
摘要： Metamaterials are artificial materials made of subwavelength elementary cells that give rise to unexpected wave properties that do not exist naturally. However, these properties are generally achieved due to 3D patterning, which is hardly feasible at short wavelengths in the visible and near-infrared regions targeted by most photonic applications. To overcome this limitation, metasurfaces, which are the 2D counterparts of metamaterials, have emerged as promising platforms that are compatible with planar nanotechnologies and thus mass production, which platforms the properties of a metamaterial into a 2D sheet. In the linear regime, wavefront manipulation for lensing, holography, and polarization control has been achieved recently. Interest in metasurfaces operating in the nonlinear regime has also increased due to the ability of metasurfaces to efficiently convert incident light into harmonic frequencies with unusual polarization properties. However, to date, the nonlinear absorption of metasurfaces has been mostly ignored. Here, we demonstrate that plasmonic metasurfaces behave as saturable absorbers with modulation performances superior to the modulation performance of other 2D materials and exhibit unusual polarimetric nonlinear transfer functions. We quantify the link between saturable absorption, the plasmonic resonances of the unit cell and their distribution in a 2D metasurface, and finally provide a practical implementation by integrating the metasurfaces into a fiber laser cavity operating in pulsed regimes driven by the metasurface properties. As such, this work provides new perspectives on ultrathin nonlinear saturable absorbers for applications where tunable nonlinear transfer functions are needed, such as in ultrafast lasers or neuromorphic circuits.
关键词： fiber lasers,metamaterials,plasmonic,saturable absorbers,metasurfaces,nonlinear optics
更新于2025-09-23 15:21:01
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Extraordinary propagation characteristics of electromagnetic waves in a one-dimensional anti-PT-symmetric ring optical waveguide network
摘要： In this paper, we design a one-dimensional anti-PT-symmetric ring optical waveguide network (1D APTSPROWN). Using the three-material network equation and the generalized Floquet-Bloch theorem, we investigate its photonic mode distribution, and observe weak and strong extremum spontaneous anti-PT-symmetric breaking points (WBPs and SBPs). Then the transmission spectrum is obtained by using the three-material network equation and the generalized eigenfunction method. The 1D APTSPROWN is found to generate ultra-strong transmission near SBPs and ultra-weak transmission near WBPs and SBPs, with the maximal and minimal transmissions being 4.08×1012 and 7.08×10-52, respectively. The maximal transmission has the same order of magnitude as the best-reported result. It is not only because the distribution of photonic modes generated by 1D APTSROWN results in the coupling resonance and anti-resonance, but also because 1D APTSROWN composed of materials whose real parts of refractive indices are positive and negative has two kinds of phase effects, which results in the resonance and anti-resonance effects in the same kind of photonic modes. This demonstrates the anti-PT-symmetric and PT-symmetric optical waveguide networks are quite different, which leads to a deeper understanding of anti-PT-symmetric and PT-symmetric structures. This work has the potential for paving a new approach for designing single photon emitters, optical amplifiers, and high-efficiency optical energy saver devices.
关键词： metamaterials.,waveguides,optical materials
更新于2025-09-23 15:21:01
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Giant circular dichroism of chiral L-shaped nanostructure coupled with achiral nanorod: Anomalous behavior of multipolar and dipolar resonant modes
摘要： Chirality, which has long been known as an intrinsic property of living organisms, has caught the interest of researchers due to the rapid emergence of chiral metamaterials. The chiroptical response of noble metal nanostructures in visible and near-infrared regions has been widely investigated. Herein, we propose a bilayer Ag metastructure, in which a chiral L-shaped nanostructure at the bottom is coupled with an achiral nanorod acquiring different positions in the top layer with respect to the long and/or short arm of the chiral L-shaped nanostructure at the bottom layer. The metastructure generates a giant circular dichroism (CD) signal resulting from the strong coupling of the multipolar and dipolar resonant modes on the two layers, in the visible and near-infrared regions. With changing the position of the achiral nanorod, an unusual reversal of the CD spectra is observed, along with a fourfold increase in CD intensity in the short wavelength range due to the multipolar resonant modes. The position of the achiral nanorod is tailored by the azimuthal angle of the substrate during the fabrication of the metastructure using the oblique angle deposition method. This study provides insights into the variation of the coupling strength between a chiral L-shaped nanostructure and an achiral nanorod. The results can be useful in designing chiral–achiral composite nanoantennas for sensing devices.
关键词： Metamaterials,Circular dichroism,Oblique angle deposition,Plasmonics,Chirality
更新于2025-09-23 15:21:01
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Design of an All-Semiconductor Selective Metamaterial Emitter in the Mid-IR Regime with Larger Feature Sizes for Thermophotovoltaic Energy Conversion Applications
摘要： A thermophotovoltaic (TPV) system converts heat that is absorbed via conduction, convection, and/or radiation to electricity. The efficiency of TPV energy conversion can be improved with a narrowband selective emitter that emits photons at just above the bandgap energy towards the TPV photodiode. We numerically report a selective metamaterial (MM) emitter design with a single layer of cylindrical structures of p-type silicon (boron-doped). Our design (substrate-free) features a peak absorbance of 94.8% at the wavelength of 3.47 lm with the smallest lateral dimension of 0.8 lm. The absorption is found to be due to the resonance of electric and magnetic fields in the structure. The larger dimensions of our selective MM emitter design make it significantly easier to pattern than many of previously reported selective MM emitters operating at similar wavelengths to that of our work. We believe that our work demonstrates a path forward for future research on larger-area all-semiconductor selective MM emitters with a variety of peak absorbance wavelengths for TPV applications.
关键词： optical absorbers,Metamaterials,selective emitters
更新于2025-09-23 15:21:01
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Phenomena of Optical Metamaterials || Disorder in Metamaterials
摘要： Since the emergence of the metamaterial, the disorder within artificially structured materials has been a subject of extensive discussions. Metamaterial at optical frequency can be considered as a kind of man-made architecture material possessing unusual properties. One of its remarkable features is that the equivalent permittivities on different directions differ from each other and can be varied by designing its structure elaborately. It is worthwhile mentioning that this property is enhanced by the presence of the disorder promises that metamaterial may serve for surface plasmons (SPs) propagating with more flexible performances than conventional metal or ordered metamaterial. For instance, dealing with the photonic crystals, some disorder can dramatically degrade the reflection and transmission properties, which are based on constructive interferences. This chapter covers three different models of the disordered metamaterials: (i) rotational disorder, (ii) sliding disorder, and (iii) positional disorder.
关键词： sliding disorder,rotational disorder,positional disorder,surface plasmons,metamaterials,disorder
更新于2025-09-23 15:21:01
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Phenomena of Optical Metamaterials || Active Optical Metamaterials
摘要： At the turn of the century, a new field of research emerged at the crossing between physics, electrical engineering, and materials science. The study of metamaterials addresses the rational design and arrangement of a material’s building blocks to attain physical properties that may go significantly beyond those of its original constituent materials. Most often, the concept of metamaterials is associated with electromagnetic wave propagation, where the engineering of resonant subwavelength structures allows for the precise control of effective wave properties. It is this advanced functionality that enables the realization of unique wave phenomena, such as the focusing of light below the diffraction limit or electromagnetic cloaking of objects—concepts that have captured the imagination of researchers and the general public alike. Importantly, the element of functionality is an integral part of the metamaterial concept.
关键词： nanoplasmonics,plasmonics,negative refractive index,optical gain,metamaterials
更新于2025-09-23 15:21:01
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A Bi-layered Chiral Metamaterial with High-Performance Broadband Asymmetric Transmission of Linearly Polarized Wave
摘要： In this paper, a novel bi-layered chiral metamaterial (CMM) is presented to realize high–efficiency broadband asymmetric transmission (AT) of linearly polarized electromagnetic wave (EM) in the microwave region from 10.1GHz to 15.1GHz. For this purpose, a pair of modified resonators is employed on two sides of a thin dielectric substrate. The simulated and measured results confirm that linearly polarized wave in the form of x-polarized or y-polarized could be nearly converted into the orthogonal polarization after transmission through the introduced prototype which is affirmed by the polarization rotation azimuth angle . The polarization conversion ratio (PCR) is more than 92% at the mentioned frequency range. Full parametric simulation of modified resonators, azimuth rotation angle, and chirality parameter variable with frequency are discussed in detail. In addition, the surface current distributions of the structure have been demonstrated to investigate the physical mechanism of the cross-polarization and corresponding polarization conversion.
关键词： Metamaterials,chiral metamaterial,linearly polarized wave,asymmetric transmission
更新于2025-09-23 15:21:01