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Lattice Zenneck Modes on Subwavelength Antennas
摘要： Optical resonances in isolated nanoparticles made out of commonly occurring materials with high optical losses, such as transition metal dichalcogenides, germanium, carbide, and others, are weak and not sufficient for field enhancement and competing with plasmonic resonances in noble metal nanoparticles. This work presents a novel approach to achieve strong resonances in the arrays of such nanoparticles with large optical losses and points to their potential for efficient light control in ultra-thin optical elements, sensing, and photovoltaic applications. Materials with large imaginary part of permittivity (LIPP) are studied and nanostructures of these materials are shown to support not only surfaces modes, known as Zenneck waves, but also modes localized on the subwavelength particle. This approach opens up the possibility of exciting strong localized nanoparticle resonances without involving plasmonic or high-refractive-index materials. Arranging LIPP particles in a periodic array plays a crucial role allowing for collective array resonances, which are shown to be much stronger in particle array than in single particle. The collective lattice resonances can be excited at the wavelength defined mainly by the array period and thus easily tuned in a broad spectral range not being limited by particle permittivity, size, or shape.
关键词： transition metal dichalcogenides,lattice resonance,Kerker effect,molybdenum diselenide,directional scattering,nanoparticle arrays
更新于2025-09-23 15:23:52
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Metasurfaces Composed of Plasmonic Molecules: Hybridization Between Parallel and Orthogonal Surface Lattice Resonances
摘要： Multiple surface lattice resonances suppress radiative losses effectively around several spectral positions, thereby enhancing the light-matter interactions and making them promising for multiwavelength related applications, and it is important to develop reliable methods to generate multiple lattice resonances. In analogy to natural materials composed of various kinds of molecules, this study proposed to construct metasurfaces with plasmonic artificial molecules, which represent distinct collective responses compared with that of single nanoparticles. It is shown that sharp multiple surface lattice resonances are excited due to the coupling between the localized resonances of plasmonic trimer molecules and the Rayleigh anomalies of the array, and there is a rarely observed parallel lattice resonance caused by the formation of equivalent dipoles perpendicular to the polarization. Particularly, even though the parallel mode is weak, a pronounced anticrossing behavior due to the hybridization with the orthogonal mode occurs when the resonance energies are approaching to each other, which results in two hybridized eigenmodes that possess both characteristics of parallel and orthogonal Rayleigh anomalies. Considering the excitation of the lattice resonances in asymmetric environments, the flexible tunability, and the ability to tailor the collective responses, metasurfaces constructed with artificial molecules are promising platforms to design ultrafast and compact photonic devices.
关键词： plasmonic molecules,mode hybridizations,metasurfaces,nanoparticle arrays,surface lattice resonances
更新于2025-09-12 10:27:22
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Ion irradiation of III–V semiconductor surfaces: From self-assembled nanostructures to plasmonic crystals
摘要： Ion-irradiation of semiconductor surfaces has emerged as a promising approach to generate a variety of self-organized nanostructures. Furthermore, the combination of focused-ion-irradiation with molecular-beam epitaxy provides unprecedented design and control of surfaces and interfaces of hybrid materials at the atomic level during fabrication. In this review, we describe the directed self-assembly of nanostructure arrays ranging from islands to nanorods to 3-dimensional nanoparticle (NP) arrays. First, we discuss focused-ion-irradiation of III–V surfaces, which leads to preferential sputtering of group V species, followed by the formation of group III-rich metallic nanostructures. For continued irradiation beyond a threshold dose, the nanoparticle (NP) evolution is determined by the sputtering yield and the local ion beam angle of incidence, resulting in arrays of nanoparticles, nanorods, or nanoparticle chains. In addition to describing the formation of close-packed embedded Ga:GaAs nanocomposites using overgrowth of focused-ion-beam fabricated NP arrays, we discuss the surface plasmon resonances of NP arrays as well as the influence of both surface and buried NP arrays on the GaAs photoluminescence efficiency. Finally, we discuss the potential of “plasmonic crystals” for plasmon-enhanced optoelectronics.
关键词： self-assembled nanostructures,ion irradiation,plasmonic crystals,molecular-beam epitaxy,III-V semiconductor,nanoparticle arrays,surface plasmon resonances,photoluminescence efficiency,focused-ion-beam
更新于2025-09-12 10:27:22
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Insights into Backscattering Suppression in Solar Cells from the Helicity-Preservation Point of View
摘要： We show that the antire?ection performance of nanoparticle arrays on top of solar-cell stacks is related to two conditions: a high enough degree of discrete rotational symmetry of the array and the ability of the system to suppress crosstalk between the two handednesses (helicities) of the electromagnetic ?eld upon light-matter interaction. For particle-lattice systems with a high enough degree of discrete rotational symmetry 2π/n for n ≥ 3, our numerical studies link the suppression of backscattering to the ability of the system to avoid the mixing between the two helicity components of the incident ?eld. In an exemplary design, we optimize an array of TiO2 disks placed on top of a ?at heterojunction solar-cell stack and obtain a threefold reduction of the current loss due to re?ection with respect to an optimized ?at reference. We numerically analyze the helicity-preservation properties of the system, and also show that a hexagonal array lattice, featuring a higher degree of discrete rotational symmetry, can improve over the antire?ection performance of a square lattice. Importantly, the disks are introduced in an electrically decoupled manner such that the passivation and electric properties of the device are not disturbed.
关键词： backscattering suppression,nanoparticle arrays,TiO2 disks,solar cells,helicity-preservation
更新于2025-09-12 10:27:22
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Plasmonic sensors relying on nanoparticle arrays created by a template-directed dewetting process
摘要： Label-free detection has promising applications in biomedical and analytical fields. Localized surface plasmon resonance (LSPR) of gold (Au) nanoparticles is sensitive to the dielectric constant of the surrounding environment. Therefore, the LSPR-based (or plasmonic) sensor is one of the most promising label-free sensing techniques. Here, we demonstrated that ordered arrays of Au nanoparticles fabricated by a template-directed dewetting process of the patterned Au film could be harnessed to construct high performance LSPR sensors. The size of the Au nanoparticles is determined by and can be simply adjusted through varying the thickness of the thermally evaporated Au film, and in turn the location of their LSPR peaks. The Au nanoparticles in the ordered array have a narrow size distribution, giving rise to sharp LSPR peaks needed for constructing high performance LSPR sensors. The LSPR sensors showed high sensitivity with a figure-of-merit value of 6.6 before they got saturated. Sensitive detection of DNA was used as an example to demonstrate the application potential of the LSPR-based sensors in biomedical fields.
关键词： Sensors,Plasmonics,Nanoparticle arrays
更新于2025-09-12 10:27:22
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Hybrid Dielectric-Plasmonic Nanocomposite Arrays for Bulk and Local Refractive Index Sensing
摘要： Plasmonics-based biosensors are often limited by material losses in the form of joule heating while all dielectric nanoparticles systems have relatively smaller local electric field enhancements. For efficient sensing, it is desirable to have a system with high sensitivity but with minimal losses. Here, we demonstrate, using numerical simulations, the capability of a hybrid dielectric-plasmonic system for refractive index sensing applications. We show that the optical resonances of such a hybrid system have smaller linewidths and the peak wavelengths are tunable. Bulk as well as local refractive index sensing are demonstrated in this work. Owing to large sensitivities of 300 nm/RIU with a figure of merit (FOM) of 10, the hybrid photonic-plasmonic systems presented here are promising materials for future biosensing applications.
关键词： Dielectric nanoparticle arrays,Hybrid nanocomposites,Plasmonic sensing
更新于2025-09-12 10:27:22