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Controllable Patterning of Hybrid Silicon Nanowire and Nanohole Arrays by Laser Interference Lithography
摘要： Metal-assisted chemical etching (MACE) is a cost-effective method to fabricate Si nanostructures including silicon nanowires (SiNWs) and silicon nanoholes (SiNHs). However, the preparation of metallic template for MACE would require complex experimental conditions including strict cleaning process and multiple steps. In our study, we applied superlens-enhanced laser interference lithography to directly fabricate complicated metallic patterns and then used MACE to obtain hybrid SiNW and SiNH arrays. Ag films were firstly deposited on Si substrates, and then a 1064 nm high power laser source was utilized to generate two-beam interference electric fields. Since Ag molecules are very sensitive to any input energy change, they tend to break up or aggregate and form different Ag patterns which have a specific energy threshold in order to lower its free energy. By manipulating the distribution of input electric field, we are able to obtain complicated metallic patterns and their corresponding Si nanostructures with feature sizes that range from tens of nanometers to several micrometers.
关键词： silicon nanowires and silicon nanoholes,silicon nanostructures,nanofabrication,metal-assisted chemical etching
更新于2025-09-23 15:19:57
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Mechanisms of Fano-resonant biosensing: Mechanical loading of plasmonic oscillators
摘要： Distinctively narrow and asymmetric line shape Fano resonances arise due to resonant interactions of sub-radiant and super-radiant modes in plasmonic nanostructures and metamaterials. A number of recent experimental studies have shown unique opportunities provided by highly dispersive Fano resonances in biosensing applications. However, there is limited understanding of Fano resonant optical response to biomolecular accumulation. Here, we introduce a phenomenological model that can precisely describe the intricate nature of the Fano resonances in plasmonic nanohole arrays and provide unambiguous physical insights into biosensing experiments. Using rigorous electromagnetic simulations and experimental measurements as benchmarking tools, we show that the non-trivial contribution of molecular accumulation to Fano resonant plasmonic response can be incorporated as a mechanical loading effect in a coupled-oscillator model. Quite remarkably, our phenomenological approach captures the complex spectral response of the Fano resonance profile and asymmetric linewidth broadening upon molecular accumulation. Furthermore, in strong agreement with our experimental measurements, we show that our parameterized model has predictive power in fine tuning the Fano resonant extraordinary light transmission lineshape using structural design parameters without resorting to electromagnetic simulations. Our phenomenological model provides a general analytical method that can be adapted to understand biomolecular detection measurements in different plasmonic and metamaterial systems.
关键词： Biosensing,Extraordinary light transmission,Plasmonics,Plasmonic nanoholes,Fano resonances,Label-free detection
更新于2025-09-23 15:19:57
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Field localization of hexagonal and short-range ordered plasmonic nanoholes investigated by cathodoluminescence
摘要： Plasmonic nanoholes have attracted significant attention among nanoplasmonic devices, especially as biosensing platforms, where nanohole arrays can efficiently enhance and confine the electromagnetic field through surface plasmon polaritons, providing a sensitive detection. In nanohole arrays, the optical resonances are typically determined by the inter-hole distance or periodicity with respect to the surface plasmon wavelength. However, for short-range ordered (SRO) arrays, the inter-hole distance varies locally, so the plasmon resonance changes. In this study, we investigate the local resonance of SRO nanoholes using a cathodoluminescence technique and compare it with hexagonally ordered nanoholes. The cathodoluminescence photon maps and resonance peak analysis reveal that the electric fields are confined at the edges of holes and that their resonances are determined by inter-hole distances as well as by their distributions. This demonstrates the Anderson localization of the electromagnetic waves showing locally enhanced electromagnetic local density of states in SRO nanoholes.
关键词： Anderson localization,biosensing,cathodoluminescence,Plasmonic nanoholes,surface plasmon polaritons
更新于2025-09-23 15:19:57
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Circular Dichroism in Low-Cost Plasmonics: 2D Arrays of Nanoholes in Silver
摘要： Arrays of nanoholes in metal are important plasmonic devices, proposed for applications spanning from biosensing to communications. In this work, we show that in such arrays the symmetry can be broken by means of the elliptical shape of the nanoholes, combined with the in-plane tilt of the ellipse axes away from the array symmetry lines. The array then di?erently interacts with circular polarizations of opposite handedness at normal incidence, i.e., it becomes intrinsically chiral. The measure of this di?erence is called circular dichroism (CD). The nanosphere lithography combined with tilted silver evaporation was employed as a low-cost fabrication technique. In this paper, we demonstrate intrinsic chirality and CD by measuring the extinction in the near-infrared range. We further employ numerical analysis to visualize the circular polarization coupling with the nanostructure. We ?nd a good agreement between simulations and the experiment, meaning that the optimization can be used to further increase CD.
关键词： nanoholes,plasmonics,circular dichroism,chirality
更新于2025-09-23 15:19:57
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Optical and Structural Phenomena at Multipulse Interference Femtosecond Laser Fabrication of Metasurfaces on a Thin Film of Amorphous Silicon
摘要： The formation of hexagonal microarrays of nanoholes (metasurfaces) in a 50-nm hydrogenated amorphous silicon film by means of three-beam interference of femtosecond laser pulses of the visible range (wavelength 515 nm) is studied experimentally with various exposures of the film. Characterization of arrays by scanning electron and optical microscopy, as well as optical transmission and reflection microspectroscopy, shows that an increase in the number of fixed energy laser pulses leads to a gradual evaporative formation of nanoholes in the film and, overall, the metasurface. Raman microspectroscopy reveals a simultaneous growth of the volume content of the crystal phase.
关键词： nanoholes,femtosecond laser,amorphous silicon,metasurfaces,interference
更新于2025-09-23 15:19:57
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Largea??Scale Plasmonic Hybrid Framework with Builta??In Nanohole Array as Multifunctional Optical Sensing Platforms
摘要： Light coupling with patterned subwavelength hole arrays induces enhanced transmission supported by the strong surface plasmon mode. In this work, a nanostructured plasmonic framework with vertically built-in nanohole arrays at deep-subwavelength scale (6 nm) is demonstrated using a two-step fabrication method. The nanohole arrays are formed first by the growth of a high-quality two-phase (i.e., Au–TiN) vertically aligned nanocomposite template, followed by selective wet-etching of the metal (Au). Such a plasmonic nanohole film owns high epitaxial quality with large surface coverage and the structure can be tailored as either fully etched or half-way etched nanoholes via careful control of the etching process. The chemically inert and plasmonic TiN plays a role in maintaining sharp hole boundary and preventing lattice distortion. Optical properties such as enhanced transmittance and anisotropic dielectric function in the visible regime are demonstrated. Numerical simulation suggests an extended surface plasmon mode and strong field enhancement at the hole edges. Two demonstrations, including the enhanced and modulated photoluminescence by surface coupling with 2D perovskite nanoplates and the refractive index sensing by infiltrating immersion liquids, suggest the great potential of such plasmonic nanohole array for reusable surface plasmon-enhanced sensing applications.
关键词： modulated photoluminescence (PL),refractive index (RI) sensing,titanium nitride (TiN),surface plasmons (SPs),plasmonic nanoholes (NHs)
更新于2025-09-23 15:19:57
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Highly uniform and symmetric epitaxial InAs quantum dots embedded inside Indium droplet etched nanoholes
摘要： III?V semiconductor quantum dots (QDs) obtained by local droplet etching technology provide a material platform for generation of non-classic light. However, using this technique to fabricate single emitters for a broad spectral range remains a signi?cant challenge. Herein, we successfully extend the QD emission wavelength to 850–880 nm via highly uniform and symmetric InAs QDs located inside indium-droplet-etching nanoholes. The evolution of InGaAs nanostructures by high temperature indium droplet epitaxy on GaAs substrate is revealed. By carefully designing the appropriate growth conditions, symmetric QDs with the a small ?ne structure splitting of only ～4.4?±?0.8 μeV are demonstrated. Averaging over the emission energies of 32 QDs, an ensemble broadening of 12 meV is observed. Individual QDs are shown to emit nonclassically with clear evidence of photon antibunching. These highly uniform and symmetric nanostructures represent a very promising novel strategy for quantum information applications.
关键词： entangled photon pairs,symmetric quantum dots,droplet etched nanoholes,molecular beam epitaxy
更新于2025-09-19 17:13:59
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Scalable and controlled creation of nanoholes in graphene by microwave-assisted chemical etching for improved electrochemical properties
摘要： Nanoholes on the basal plane of graphene can provide abundant mass transport channels and chemically active sites for enhancing the electrochemical performance. However, current thermal chemical etching processes to manufacture these nanoholes commonly suffer from insufficient process efficiency, scalability and controllability, due to the conventional bulk heating strategy lacks capability to promote the etching reactions. To address this issue, a novel process is developed using microwave irradiation to promote and control the chemical etching of graphene. In this process, the microwave can induce a selective heating of graphene in the liquid solution and then facilitate the etching reactions occurring on the graphene-etchant interface. Applying this strategy, a remarkable reduction of processing time from hour-scale to minute-scale compared to the conventional approaches have been achieved with the control of the population and area percentage of nanoholes on the graphene basal plane. DFT and MD simulations revealed that the formation of nanoholes originated from the cyclic etchant oxidation process occurring at the edge-sites atoms around pretreated vacancies on graphene basal plane. The obtained holey graphene oxide sheets exhibit excellent capacitive performance and electrochemical catalytic activity due to the improvements in the accessible surface area, ion diffusion, and heterogeneous charge transfer.
关键词： nanoholes,microwave-assisted chemical etching,electrochemical properties,graphene,scalable fabrication
更新于2025-09-16 10:30:52
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Polarization controllable plasmonic focusing based on nanometer holes
摘要： Two kinds of plasmonic lenses are proposed based on phase compensation. controllable foci focusing of the second kind of plasmonic lens can be utilized as dependence focusing. Two or four foci of the first kind of plasmonic lens and two Each kind of plasmonic lens is comprised of four sets of nanohole arrays, and two sets principles make the proposed plasmonic lenses show the different polarization the surface plasmon polaritons reaching to the focal spot. The different design optical switch and logic judgment. Theoretic analysis, numerical calculations and experiment measurement verify the focusing performance of our proposed plasmonic and the rotation angle of holes compensates respectively for the phase difference of of face-to-face nanohole arrays are planar symmetric. The adjustment of separation Polarization controllable plasmonic focusing based on
关键词： Nanoholes,Plasmonic focusing,Surface plasmon polaritons,Polarization
更新于2025-09-12 10:27:22
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Large-scale highly ordered periodic Au nano-discs/graphene and graphene/Au nanoholes plasmonic substrates for surface-enhanced Raman scattering
摘要： In this paper, the study of using masks to directly generate large area, highly ordered and periodical nanostructure has been exhibited. Periodic Au nano-discs(NDs) arrays have been fabricated on top of graphene by using holey Si3N4 mask which is directly fixed on top of graphene and Au metal is deposited through the holes in mask by thermal evaporation method under vacuum condition. This fabrication method provides an easy, fast and cost efficiency way to generate periodical nanostructure. Also, Au nanoholes(NHs) structure has been studied by using holey Si3N4 as a template. The surface-enhanced Raman scattering (SERS) sensitivities of periodical Au NDs/graphene and graphene/Au NHs hybrid structures have been systematically studied. The internal mechanisms could be explained by chemical mechanism effect of graphene and electromagnetic mechanism effect of metallic nano-structures. The enhancement factors have been systematically investigated by varying the diameter and the thickness of Au discs and Au NHs. Raman mappings of Au NDs with 2.5 μm diameter illustrate that the larger SERS enhancements exist in the rim of NDs which has good agreement with the electric field simulation result. The SERE enhancement factors of fluorescein obtained from Au NDs/graphene substrates shows an improvement factor of 500% in comparison of graphene substrate. The calculated SERS enhancement factors of graphene/Au NHs achieve 1,200% in comparison of graphene/planar Au film substrate.
关键词： graphene,surface-enhanced Raman scattering (SERS),periodic,Au nano-discs (NDs),Au nanoholes (NHs)
更新于2025-09-12 10:27:22