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Multiple embedded eigenstates in nonlocal plasmonic nanostructures
摘要： Trapping light in open cavities is a long sought “holy grail” of nanophotonics. Plasmonic materials may offer a unique opportunity in this context, as they may fully suppress the radiation loss and enable the observation of spatially localized light states with an infinite lifetime in an open system. Here, we investigate how the spatial dispersion effects, e.g., caused by the electron-electron interactions in a metal, affect the trapped eigenstates. Heuristically, one may expect that the repulsive-type electron-electron interactions should act against light localization, and thereby that they should have a negative impact on the formation of the embedded eigenstates. Surprisingly, here we find that the nonlocality of the material response creates new degrees of freedom and relaxes the requirements for the observation of trapped light. In particular, a zero-permittivity condition is no longer mandatory and the same resonator shell can potentially suppress the radiation loss at multiple frequencies.
关键词： spatial dispersion,nonlocal plasmonic nanostructures,light trapping,embedded eigenstates
更新于2025-09-19 17:13:59
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X-shaped chiral plasmonic nanostructured metasurfaces: A numerical study
摘要： In this paper, the author reports a numerical investigation of spectroscopic circular dichroism (CD) properties, near-field enhancement, and optical chirality near a chiral plasmonic nanostructured metasurface. The individual constituents of the metasurface consist of periodic X -shaped Au nanostructures on a glass substrate. The nanostructure is made of two overlapping nanorods, including one vertical nanorod and one tilted nanorod. Strong CD of the metasurface was observed and tunable upon rotation of the individual nanorods due to geometrical symmetry breaking. Near-field enhancement of up to 5 times and a large local optical chirality were found at a plane 20 nm above the X -shaped nanostructure. Electromagnetic modeling analysis provides valuable guidelines for designing alternative two-dimensional chiral metamaterials that have potential applications for enhanced molecule and chiral plasmon interaction.
关键词： Metasurfaces,Symmetry breaking,Chiral plasmonic nanostructures,Circular dichroism
更新于2025-09-19 17:13:59
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Self-Assembled Nanohelix for White Circularly Polarized Luminescence via Chirality and Energy Transfer
摘要： Chiral nanostructures and their optical activity have been attracting great interest. Here, we designed enantiomer bolaamphiphile containing a naphthalene moiety (bola-1) and alkyl spacer, and investigated their self-assembly as well as optical activity. It was found the compound could form gels in various organic or mixed organic/water mixtures. In mixed DMSO/water, it formed nanohelix. Due to the fluorescent nature of the naphthyl group, the nanohelix showed both CD and circularly polarized luminescence (CPL). When three achiral fluorescent molecules, pyrene-1-carboxylic acid (D2), rhodamine 110 (D3) and rhodamine B (D4), were incorporated into the helical structures formed by bola-1, the nanohelix could be remained and the CPL from the dye molecules could be induced. In addition, an energy transfer occurred between the bola-1 nanohelix and the dyes. By mixing the different emission dyes with the bola-1 in an appropriated ratio, a white CPL was obtained. It was found the dissymmetry factor of the white CPL could be increased through the energy transfer. This work provided a new convenient and efficient way of fabricating while CPL.
关键词： nanohelix,white CPL,circularly polarized luminescence,energy transfer,optical activity,Chiral nanostructures,bolaamphiphile
更新于2025-09-19 17:13:59
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Incorporating Aluminum Plasmonic Nanohemisphere Arrays into Organic Ultraviolet Photodetectors for Improved Photoresponse
摘要： Aluminum nanostructures, which support surface plasmon resonances in the UV spectral range, were incorporated into conventional organic UV photodetectors with a structure of indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/poly(9,9-dioctyl?uorene-alt-bithiophene) (F8T2):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM)/LiF/Al. Nanohemisphere arrays (NHSAs) were imprinted into the top surface of the soft organic active layer, thus transferring the pattern to the subsequently thermally deposited layers of LiF and Al. NHSA-top devices and ?at-top control devices were investigated by 3-dimensional ?nite-di?erence time-domain (3D-FDTD) electromagnetic simulations. Improved UV active layer absorbance and enhanced electric ?elds in the nanohemispheric region at the top of the active layer were shown for devices with the NHSA-top. The impact of the NHSA-top was found to be more signi?cant for devices with thin active layers and to gradually decrease with increasing active layer thickness. Fabricated NHSA-top devices with thin active layers exhibited improved photoresponse in terms of external quantum e?ciency, speci?c detectivity and on?o? response speed compared to ?at-top devices under 330 nm illumination and 0 to ?1 V bias. The method developed in this work provides a versatile and e?ective way to incorporate plasmonic nanostructures into optoelectronic devices to enhance device performance.
关键词： enhanced photoresponse,aluminum plasmonic nanostructures,organic photodetectors,nanoimprinting,ultraviolet photodetectors
更新于2025-09-19 17:13:59
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Imitating the effect of amplified spontaneous emission pedestal at relativistically intense laser interaction with nanostructured solid targets
摘要： We investigated the effect of focusing sub-nanosecond laser radiation with varied fluence onto the surface of different flat and nanostructured targets utilized in ultra-high intensity laser-plasma experiments. Thus, we modeled the action of the prepulse, referred to as an amplified spontaneous emission pedestal, typically present for a relativistic (with peak intensity over 1018 W cm?2) laser pulse with naturally limited contrast. The suppressed melting threshold was detected for the sub-wavelength scale structured material. Local melting leading to distortion of initial structures was detected at a fluence of ~0.2 J cm?2 and below, or 3–5 times lower compared to the flat substrate melting threshold. It is also demonstrated that the threshold lowering is dependent on the production method of the structures, which may be attributed to increased absorption and suppressed heat transfer into the bulk.
关键词： high intensity laser interaction,amplified spontaneous emission pedestal,laser melting,sub-nanosecond pulse,nanostructures
更新于2025-09-19 17:13:59
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Time-dependent optimization of laser-produced molecular plasmas through high-order harmonic generation
摘要： Analysis and characterization of laser-produced plasmas (LPPs) require the advanced methods for determination of different multiparticle component formation and spreading. Time-resolved high-order harmonic generation (HHG) in spreading LPPs allows determining optimal conditions for this process. One of the most important parameters of HHG in LPP is the delay between the heating and driving pulses. We demonstrate that the optimization of delays allows achieving the maximal harmonic yields in LPP created on the surfaces of the solid targets possessing different molar masses (m). The optimal delays (t) for B4C, ZnO, GaP, GaAs, and Ag2S plasmas were determined to be approximately 200, 300, 350, 500, and 700 ns, respectively. These variations of delays correspond to the t1(m)0.5 dependence for different materials. We demonstrate the applicability of the proposed method for analysis of the resonance-enhanced harmonics in atomic and molecular plasmas (Mo and MoS2) and for studies of large perovskite aggregates as potential emitters of harmonics. This diagnostic technique can also be applied to the analysis of the presence of different nanostructures in LPPs through HHG with a high spatiotemporal resolution.
关键词： perovskite aggregates,laser-produced plasmas,molar masses,time-resolved,high-order harmonic generation,optimization,nanostructures,resonance-enhanced harmonics
更新于2025-09-19 17:13:59
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Emerging Waveguide Technology || Photonic Crystal Waveguides
摘要： The original results of theoretical and experimental studies and the properties of microwave one-dimensional waveguide photonic crystals have been generalized. Methods for describing the electrodynamic characteristics of photonic crystals and their relationship with the parameters of periodic structures filling the waveguides have been presented. The results of an investigation on the characteristics of microwave waveguide photonic crystals made in the form of dielectric matrices with air inclusions have been presented. The model of effective dielectric permittivity has been proposed for describing the characteristics of the investigated photonic crystals containing layers with a large number of air inclusions. New types of microwave low-dimensional waveguide photonic crystals containing periodically alternating elements that are sources of higher type waves have been described. The possibility of effective control of the amplitude-frequency characteristics of microwave photonic crystals by means of electric and magnetic fields has been analyzed. Examples of new applications of waveguide photonic crystals in the microwave range have been given: the measuring parameters of the materials and semiconductor nanostructures that play the role of the microwave photonic crystals' periodicity defect; the resonators of near-field microwave microscopes; small-sized matched loads for centimeter and millimeter wavelength ranges on the basis of microwave photonic crystals.
关键词： low-dimensional photonic crystal,electrically controlled characteristics,forbidden bands,defect mode,measurement of micro- and nanostructures,microwave matched loads,microwave photonic crystals
更新于2025-09-19 17:13:59
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Multifunctional 3D micro-nanostructures fabricated through temporally shaped femtosecond laser processing for preventing thrombosis and bacterial infection
摘要： Blood-contacting medical devices that directly inhibit thrombosis and bacterial infection without using dangerous anticoagulant and antibacterial drugs can save countless lives but have proved extremely challenging. Here, a useful methodology is proposed that employs temporally shaped femtosecond laser ablation combined with fluorination to fabricate a multifunctional three-dimensional (3D) micro-nanostructures with excellent hemocompatibility, zero cytotoxicity, outstanding biocompatibility, bacterial infection prevention, and long-term effectiveness on NiTi alloys. This multifunctional 3D micro-nanostructures presents 0.1% hemolysis ratio, almost no platelet adhesion and activation, repels blood to inhibit blood coagulation in vitro, maintains 100% cell viability and has exceptional stability over 6 months. Moreover, the multifunctional 3D micro-nanostructures simultaneously suppresses bacterial colonization to form biofilm and kills 100% colonized P. aeruginosa and 95.6% colonized S. aureus after 24h incubation, and bacterial residues can be easily removed. The fabrication method in this work has the advantages of simple processing, high efficiency, high quality and high repeatability, and the new multifunctional 3D micro-nanostructures can effectively prevent thrombosis and bacterial infection, which can be widely applied to various clinical needs such as biomedical devices and implants.
关键词： excellent-hemocompatibility,temporally shaped femtosecond laser,no-contamination,bacterium-free,multifunctional 3D micro-nanostructures
更新于2025-09-19 17:13:59
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Femtosecond Laser-Induced Periodical Nanomodification of Surface Composition
摘要： Nanoscale periodical chemical composition modification of different two-component compound materials GaAs, CdTe, W0.5C and TiC was realized for the first time through multi-shot femtosecond laser irradiation of their surfaces. The resulting surface modification represents periodical nanoscale ripples with different chemical composition in valleys and ridges. The underlying mechanism is related to a sequence of elementary processes, such as laser excitation surface plasmon-polariton, their interference with the incident laser radiation, inhomogeneous surface heating and incongruent cavitation-like material removal. The latter mechanism is responsible for higher evaporation rate of the components with higher volatility, resulting in growth of surface concentration of low-volatility components.
关键词： ablation,surface modification,nanostructures,femtosecond laser pulses
更新于2025-09-19 17:13:59
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Plasmonic-Active Nanostructured Thin Films
摘要： Plasmonic-active nanomaterials are of high interest to scientists because of their expanding applications in the field for medicine and energy. Chemical and biological sensors based on plasmonic nanomaterials are well-established and commercially available, but the role of plasmonic nanomaterials on photothermal therapeutics, solar cells, super-resolution imaging, organic synthesis, etc. is still emerging. The effectiveness of the plasmonic materials on these technologies depends on their stability and sensitivity. Preparing plasmonics-active nanostructured thin films (PANTFs) on a solid substrate improves their physical stability. More importantly, the surface plasmons of thin film and that of nanostructures can couple in PANTFs enhancing the sensitivity. A PANTF can be used as a transducer for any of the three plasmonic-based sensing techniques, namely, the propagating surface plasmon, localized surface plasmon resonance, and surface-enhanced Raman spectroscopy-based sensing techniques. Additionally, continuous nanostructured metal films have an advantage for implementing electrical controls such as simultaneous sensing using both plasmonic and electrochemical techniques. Although research and development on PANTFs have been rapidly advancing, very few reviews on synthetic methods have been published. In this review, we provide some fundamental and practical aspects of plasmonics along with the recent advances in PANTFs synthesis, focusing on the advantages and shortcomings of the fabrication techniques. We also provide an overview of different types of PANTFs and their sensitivity for biosensing.
关键词： localized surface plasmon resonance (LSPR),plasmonics,gold nanostructures,biosensing,thin film,lithography,nanohole array,nanofabrication
更新于2025-09-19 17:13:59