Expanding the hot-spot distribution in hybrid Nanohole Arrays toward high-performance light trapping

Expanding the hot-spot distribution in hybrid Nanohole Arrays toward high-performance light trapping | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Expanding the hot-spot distribution in hybrid Nanohole Arrays toward high-performance light trapping Jie Zheng, Shiyu Zhang, Xiangting Xie, Chao Xie, Junjie Mao, Yarong Su, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8599333/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Mar, 2026 Read the published version in Plasmonics → Version 1 posted 8 You are reading this latest preprint version Abstract Trapping light and enhancing electromagnetic fields in plasmonic nanostructures are crucial for advanced applications, such as for surface-enhanced Raman scattering, surface-enhanced fluorescence and plasmon-enhanced second-harmonic generation (PESHG) at subwavelength scales. Expanding the spatial distribution of enhanced electromagnetic fields, i.e., hot spots, has become a vital strategy to significantly enhance the performance of advanced nanophotonic applications. In this work, we propose a strategy of hybrid metal-dielectric (MD) nanohole arrays by introducing low-loss silicon nitride (Si 3 N 4 ) dielectric layers into aluminum (Al) nanohole arrays to realize the strong light-trapping and expand the spatial distribution of hot spots at MD interfaces by changing the diameter of nanohole. The mechanism governing these phenomena is deriving from the occurrence of dielectric-mediated plasmonic coupling, facilitating the translation of local light confinements governed by plasmon-driven resonances to dielectric components and LSPR-excited hot-spots redistribution in plane. Moreover, we introduce both label and label-free optical probes regarding the photoluminescence enhancement of MoS 2 and PESHG to verify and quantify the effect of expanded hot-spot distribution in hybrid Al-Si 3 N 4 nanohole arrays on the enhancement of light-matter interaction. This work may provide a theoretical and experimental mechanism for expanding the potential in characterizing and quantifying hot-spot distribution in advanced optical nanodevices. plasmonic nanostructures light trapping plasmon-enhanced second-harmonic generation surface-enhanced fluorescence hybrid configurations Figures Figure 1 Figure 2 Figure 3 Figure 4 1. INTRODUCTION High efficiently manipulating the light and enhancing electromagnetic (EM) fields have emerged as a critical capability in numerous advanced applications, such as surface-enhanced Raman scattering (SERS) [ 1 , 2 ], surface-enhanced fluorescence (SEF) [ 3 , 4 ], nonlinear optics, and ultrasensitive sensors [ 5 – 10 ]. The spatial position of enhanced EM fields commonly refers to as hot spots [ 11 ]. Traditionally, these hot spots are highly confined to extremely small scales, such as the gap between closely spaced nanoparticles or the sharp tip of plasmonic nanostructures [ 12 ]. Though these localized hot spots offer higher EM enhancements, the limitation of modal volumes often restricts the overall performance and scalability of nanophotonic devices. Expanding the modal volume of hot spots has become a vital strategy to elevate the performance of nanophotonic devices. By extending the distribution of hot spots, more molecules or fluorophores can interact with enhancement EM fields, thereby significantly improving the detection efficiency and signal-to-noise ratio in applications such as SERS and SEF. Several advanced strategies have been put forward to address these issues, for instance, optimizing structural design, engineering material, and introducing dielectric components that facilitate the redistribution of localized EM energies [ 13 – 15 ]. Here, we found that the mid-refractive-index Si 3 N 4 dielectric material can excite multipolar magnetic and electric resonances in the visible and near-infrared (NIR) regions [ 16 ]. Meanwhile, plasmonic aluminum (Al) material can support surface plasmonic resonances (SPRs) in a wide spectrum spanning ultraviolet (UV) to NIR regions [ 16 , 17 ]. In this paper, we put forward a strategy of hybrid metal-dielectric (MD) nanohole arrays to realize trapping light, transferring energy and expanding the modal volume of hot spots at MD interfaces by introducing low-loss Si 3 N 4 dielectric layers into Al nanohole arrays. Introduced dielectric-mediated plasmonic coupling facilitates the distribution of enhanced EM fields from visible to NIR regions (i.e., from 550 to 1000 nm). Theoretical and experimental results demonstrate that the EM energy is modulated from the air into the side wall of nanoholes as the thickness of Si 3 N 4 dielectric layer increases. The in-plane hot-spot distribution can be extended by changing the diameter of nanohole. Furthermore, the monolayer (1-L) MoS 2 deposited on plasmonic Al nanohole arrays with different diameters are used to perform photoluminescence (PL) signal, verifying that the plasmonic Al nanohole arrays with 480-nm diameter can obtain as high as 4-fold compared to that with 680-nm diameter. Meanwhile, we further investigate their performance as a nonlinear platform through plasmon-enhanced second-harmonic generation (PESHG), revealing that PESHG signals progressively decrease in the amplitude as Al nanohole diameters increases. These experimental results serve as both label and label-free optical probe to remotely monitor expanding regions of hot spots. Our work may provide a theoretical and experimental mechanism for realizing strong light-matter interaction. 2. EXPENRIMENTAL SECTION In this study, highly uniform hybrid MD arrays by integrating plasmonic Al nanohole arrays with Si 3 N 4 dielectric layer are fabricated by adopting nanosphere self-assembly technology combined with film depositing and reactive ion etching (RIE) techniques. Briefly, Al film with 100 nm thickness, as reflect films, is deposited onto the silicon substrate by means of electron beam film deposition system. Then, Si 3 N 4 film with 20-nm thickness is deposited onto the surface of Al film by means of plasma enhanced chemical vapor deposition (PECVD). Subsequently, the highly uniform polystyrene (PS) spheres with 750-nm diameter are hexagonal close-packed onto the surface of Si 3 N 4 film. The diameters of PSs can be modulated by varying the etch time in during of RIE. Finally, a 100-nm Al film is deposited onto the surface of prepared PS spheres. The adjustable Al nanohole arrays can be successfully obtained when the PS spheres are removed by utilizing lift-off technique. A schematic perspective view is shown in Fig. 1 (a). The top-view scanning electron microscope (SEM) images in the Fig. 1 (b) uncover that plasmonic Al nanohole arrays show high uniformity, which guarantees the repeatability and identity of signal acquisition. Figure 1 (c) displays the elements component of Al, silicon (Si), and oxygen (O) for large-scale sampled regions. 3. RESULTS AND DISCUSSION We theoretically investigate the thickness-dependent effect of the Si 3 N 4 dielectric layer on near and far-field characteristics, ranging from 0 nm to 110 nm with 20 nm increments. Simulated results demonstrate that the resonant peaks of absorption (A = 1-R-T, T = 0) occur evidently red shift from 650 nm to 860 nm, as shown in Fig. 2 (a). We can intuitively observe that the full width at half-maximum (FWHM) and near-field energy are influenced by the thickness of the Si 3 N 4 dielectric layer, as shown in Fig. 2 (b). With the increase of the Si 3 N 4 dielectric layer, the FWHM is broadened from 33 nm to 183 nm and near-field energy exponential decay. To clearly represent the evolution of near-field energy densities, we provide the distribution of local EM field for the varied thickness of the Si 3 N 4 dielectric layer as shown in Fig. 2 (c). The TM polarized incident light is adopted at normal illumination (see the inset in Fig. 2 (a)). For the absence of Si 3 N 4 dielectric layer, the energy will be more dispersed into the free space. The resonant mode is mainly deriving from the located surface plasmon resonance (LSPR) generated by the corner of Al nanoholes. The distribution of near-field energy densities states that the Al nanoholes without dielectric layer can be considered as dispersive nanostructures. With the increase of dielectric-layer thicknesses, the distribution of near-field energy gradually transfers into the bottom layer and inner of Al nanoholes. For the case of 0-nm thickness dielectric layers, the line width is 33 nm and the electric-field strength is strongest at the upper and the vertical wall of Al nanoholes. When the thickness is increased to 100 nm, the near-field energy is almost squeezed into Al nanoholes. Meanwhile, the electric-field strength is concurrently weakened and FWHM is evidently broaden. In hybrid MD arrays, evaluating the strongest hot spots region as the near-field enhancement located at the corner of the Al nanoholes. When introducing dielectric layer, the near field is effectively modulated from the local region to the entire surface and bulk of the plasmonic Al nanohole arrays. The results provide theoretically foundation that the near-field energy can be modulated by the thickness of dielectric layer. Therefore, 20-nm thickness Si 3 N 4 film has been adopted to acted as dielectric layer for extending hot-spot distribution in plane. Experimentally, plasmonic Al nanohole arrays with 20-nm Si 3 N 4 layer have been manufactured to validate the modulation of near-field energy and the spatial distribution of hot spots region. The diameters of the plasmonic Al nanohole arrays can be adjusted by the etch time during RIE processes. Figure 3 (a) shows the top-view SEM images of four samples with the same periodicity and different nanoholes’ diameters, i.e., D = 680 nm, 600 nm, 550 nm, and 480 nm. First, we theoretical and experimental investigate the effect of nanoholes’ dimensions on the far-field optic characteristics and near-field energy distribution, as shown in Fig. 3 (b). The results demonstrate that the resonant peaks slightly blue shift and the FWHM is reduced as the decreasing of Al nanoholes diameters. The distributions of near-field energy indicate that the LSPR-excited energy is gradually dispersed to the free space with the increasing of Al nanohole diameters, and the ability of the energy localization is getting weakened. The simulation results are in agreement with the experimental results. Importantly, we offer the PL enhancement of MoS 2 to verify that near-field energy transfer from air layer to the inner of Al nanoholes. The plasmonic Al nanohole arrays, generating strong LSPR, can enhance the PL signal of 1-L MoS 2 . The MoS 2 transferred onto plasmonic Al nanohole arrays is first verified to be a monolayer by Raman spectroscopy, as shown in Fig. 3 (c) and Fig. 3 (d). The wave number spacing between the two modes, A 1g and E 2g 1 remains 18 cm -1 after the transfer, which confirms that MoS 2 transferred onto plasmonic Al nanohole arrays is a monolayer [ 4 , 18 – 20 ]. Like the well-known Purcell effect [ 3 ], strong LSPR can change the local density of states of 1-L MoS 2 , which leads to additional emission pathways of MoS 2 and further enhances the PL signals. The PL signals show that plasmonic Al nanohole arrays with a diameter of 480 nm has better enhancement of PL signals, which is four times more than that of the nanohole with a diameter of 680 nm. Interestingly, the near-field energy also can be adjusted by controlling the nanoholes diameters. One of primary applications benefiting from strong near-field energy confinements in plasmonic metasurfaces is nonlinear frequency conversion, where harmonic generation scales with the enhancement of local EM fields [ 20 ]. To demonstrate the unique optical property of proposed configurations, we investigate their performance as a nonlinear platform for boosting the frequency conversion through second-harmonic generation (SHG). As illustrated in Fig. 4 (a), we introduce a laboratory-built SHG spectrometer to perform multiparameter-resolved measurements, including analyses of polarization dependence, geometrical influence, and incident power variation. These experiments aim to elucidate the amplification of nonlinear optical signals resulting from local-field enhancements near metallic nanohole elements. As anticipated, frequency-doubled emissions are observed in patterned samples [Figure 4 (b)], along with the measured SHG power emitted from nanohole arrays with D = 480 nm exhibiting a quadratic dependence on pumping-laser powers [Figure 4 (c)], consistent with characteristic behaviors of SHG processes. Additionally, we discover that SHG signals emitted from proposed nanodevices greatly outperform those emitted from unpatterned metallic films [Figure 4 (b)]. These observations further confirm the efficient near-field energy confinement of patterned metallic counterparts. To verify this assumption, polarization-resolved measurements have been conducted as shown in Fig. 4 (d). Considering that pumping-laser pulses propagate along the z axis, and the polarization orientation of incident beams can thus be defined by an azimuthal angle (α) with the y axis, ranging from 0° to 360° [see the inset of Fig. 4 (a)]. Experimental results reveal similar polar patterns across four cases with D = 480 nm, 550 nm, 600 nm, and 680 nm, accompanied by a progressive decrease in the amplitude as D increases. This trend can be attributed to the influence of nanohole dimensions on near-field energy distributions, as previously illustrated in Fig. 3 (b). In centrosymmetric plasmonic metals such as Al, second-order nonlinear responses primarily originate at interfaces [ 21 ]. Accordingly, we infer that retrieved SHG responses predominantly originate from the face-up surface of Al nanoholes. Furthermore, the vertically-aligned polarization moment exhibits rotational symmetry around the normal direction, consistent with the quasi-isotropic polarization dependence observed in SHG emission profiles [ 22 ]. Results mentioned above make feasible an ultrasensitive SHG probe of remotely monitoring the quantitative variation of local-field energy densities near the sidewall of nanoholes’ elementary units [ 23 ]. 4. CONSLUSION In conclusion, the hybrid MD arrays integrating metal nanohole arrays with dielectric layer have been successfully fabricated. The EM energy is modulated from the air into the inner of metal nanohole arrays and the hot spots region can be effectively extended by changing the thickness of dielectric layer and the diameters of metal nanohole arrays. The improved uniformity and extended hot spots region offer substantial benefits in various applications. The 1-L MoS 2 deposited on hybrid MD arrays with different diameters are used to perform PL signal and the results demonstrate that the plasmonic Al nanohole arrays with 480-nm diameter can obtain as high as 4-fold compared to that with 680-nm diameter. Furthermore, the experimental results of PESHG demonstrate that SHG signals emitted from proposed hybrid MD arrays and a progressive decrease in the amplitude as Al nanohole diameter increases. This work may provide a theoretical and experimental mechanism for expanding the potential in maneuvering light and extending hot spots region from surface enhancement to bulk phase modulation. Declarations Data Availability Statement Data will be made available upon reasonable request. AUTHOR INFORMATION Corresponding Author J. Zheng-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China; orcid.org/0000-0002-5674-4979; Email: [email protected] Shao. X. Shen-College of Information Science and Engineering, Fujian Provincial Key laboratory of Light Propagation and Transformation, Huaqiao University, Xiamen 361021, China; Email: [email protected] Jian. Q. Zhu-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China; Email: [email protected] Authors Shi. Y. Zhang-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China. Xiang. T. Xie- College of Information Science and Engineering, Fujian Provincial Key laboratory of Light Propagation and Transformation, Huaqiao University, Xiamen 361021, China. C. Xie- College of Information Science and Engineering, Fujian Provincial Key laboratory of Light Propagation and Transformation, Huaqiao University, Xiamen 361021, China. Jun. J. Mao-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China. Ya. Y. Su-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China. Author Contributions J.Z. and S.S.X.: Conceptualization, Methodology, Writing. S.Y.Z., X.X.T., and X.C.: Data curation, Investigation. J.J.M. and Y.R.S.: Visualization. J.Q.Z: Validation. J.Z. and S.S.X.: Supervision, Reviewing, Editing. †Jie Zheng and Shiyu Zhang contributed equally to this work. Funding Sources This work was supported by the National Natural Science Foundation of China (12104326, 12104329, and 12004121), Natural Science Foundation of Sichuan Province (2023NSFSC1305), Natural Science Foundation of Fujian Province (2024J01080); Fundamental Research Funds for the Central Universities (ZQN-1006). Notes The authors declare no competing financial interest. 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Cite Share Download PDF Status: Published Journal Publication published 25 Mar, 2026 Read the published version in Plasmonics → Version 1 posted Editorial decision: Revision requested 13 Feb, 2026 Reviews received at journal 24 Jan, 2026 Reviewers agreed at journal 24 Jan, 2026 Reviewers agreed at journal 24 Jan, 2026 Reviewers invited by journal 22 Jan, 2026 Editor assigned by journal 14 Jan, 2026 Submission checks completed at journal 14 Jan, 2026 First submitted to journal 14 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8599333","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":579954307,"identity":"3be24ed1-13db-47a4-8e65-91c7c2017f0b","order_by":0,"name":"Jie Zheng","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6ElEQVRIiWNgGAWjYDACCRDBI8HAz8DYABE5QKwWyQbStACBAVwlIS3ys5uPPfwiYyFnfP5w4+fCNgY5vhsJjJ8L8GhhnHMs3ViGR8LY7EZis/TMNgZjyRsJzNIz8Ghhlsgxk5bgkUjcdoOxjZm3jSFxw40ENmYePFrYJPK/gbTUb+4/CNZST1ALj0QOm+QHHokEA4ZEsJYEA0JaJCTSzKSBGg1ngPzCc07CcOaZh0AGHi3yM5KfSf7sqZPn7z/+8DNPmY083/Hkg5/xaQEBZt4ehK1ADItTPIDxxw+CakbBKBgFo2AkAwDAgULP+OdNEgAAAABJRU5ErkJggg==","orcid":"","institution":"Sichuan Normal University","correspondingAuthor":true,"prefix":"","firstName":"Jie","middleName":"","lastName":"Zheng","suffix":""},{"id":579954318,"identity":"83150c2f-33a7-4678-bc7b-10281a9d0c9c","order_by":1,"name":"Shiyu Zhang","email":"","orcid":"","institution":"Sichuan Normal University","correspondingAuthor":false,"prefix":"","firstName":"Shiyu","middleName":"","lastName":"Zhang","suffix":""},{"id":579954332,"identity":"662241c5-f547-4912-b3ae-bed8855c9bec","order_by":2,"name":"Xiangting Xie","email":"","orcid":"","institution":"Huaqiao University","correspondingAuthor":false,"prefix":"","firstName":"Xiangting","middleName":"","lastName":"Xie","suffix":""},{"id":579954336,"identity":"625116da-7931-4a2a-9e18-2077191dca28","order_by":3,"name":"Chao Xie","email":"","orcid":"","institution":"Huaqiao University","correspondingAuthor":false,"prefix":"","firstName":"Chao","middleName":"","lastName":"Xie","suffix":""},{"id":579954346,"identity":"a598a2bc-f1ef-4c09-a565-44025939e809","order_by":4,"name":"Junjie Mao","email":"","orcid":"","institution":"Sichuan Normal University","correspondingAuthor":false,"prefix":"","firstName":"Junjie","middleName":"","lastName":"Mao","suffix":""},{"id":579954355,"identity":"3a67efbb-f4db-4235-93f3-5b3211ac54d2","order_by":5,"name":"Yarong Su","email":"","orcid":"","institution":"Sichuan Normal University","correspondingAuthor":false,"prefix":"","firstName":"Yarong","middleName":"","lastName":"Su","suffix":""},{"id":579954360,"identity":"5fd0ab63-dc83-4439-8a58-766e6a6d3b76","order_by":6,"name":"Jianqi Zhu","email":"","orcid":"","institution":"Sichuan Normal University","correspondingAuthor":false,"prefix":"","firstName":"Jianqi","middleName":"","lastName":"Zhu","suffix":""},{"id":579954364,"identity":"72ccf41c-8e5f-4c47-8bfa-4940fb18554e","order_by":7,"name":"Shaoxin Shen","email":"","orcid":"","institution":"Huaqiao University","correspondingAuthor":false,"prefix":"","firstName":"Shaoxin","middleName":"","lastName":"Shen","suffix":""}],"badges":[],"createdAt":"2026-01-14 08:23:54","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8599333/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8599333/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11468-026-03351-x","type":"published","date":"2026-03-25T16:10:40+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":101196087,"identity":"e64c6f1a-4f04-41fe-8d3b-190c5c4a994d","added_by":"auto","created_at":"2026-01-27 08:12:32","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":95630,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic of hybrid MD arrays; (b) Top SEM image of hybrid MD arrays. Scale bar, 500 nm; (c) The elemental ratio of Al, Si and O.\u003c/p\u003e","description":"","filename":"Figure1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8599333/v1/5fdb12251292c6ed4f540b5c.jpg"},{"id":101196090,"identity":"3830417e-c456-4ede-bc41-750f4938970f","added_by":"auto","created_at":"2026-01-27 08:12:32","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":156972,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Absorption spectra of plasmonic Al nanohole arrays with different thicknesses of Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer; (b) Effect of different thicknesses of Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer on FWHM and the near-field energy; (c) The distributions of near-field energy with different thicknesses of Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer.\u003c/p\u003e","description":"","filename":"Figure2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8599333/v1/8c206150e2a3776c4d85aaab.jpg"},{"id":101196088,"identity":"539d5e8c-4526-4c9f-b93a-bf51e8326be3","added_by":"auto","created_at":"2026-01-27 08:12:32","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":161856,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Typical SEM images of plasmonic Al nanoholes with different diameters. The figures from up to bottom denote D=680 nm, 600 nm, 550 nm, and 480 nm, respectively; (b) Reflectance spectra of plasmonic Al nanoholes with different diameters. The left column displays theoretical results and the right column show experimental results. The insets denote the distributions of near-field energy; (c) Raman spectra of MoS\u003csub\u003e2\u003c/sub\u003e transferred on plasmonic Al nanohole arrays; (d) the photoluminescence signals of monolayer MoS\u003csub\u003e2\u003c/sub\u003e transferred on silicon wafers and plasmonic Al nanoholes with different diameters at 532-nm excitation light.\u003c/p\u003e","description":"","filename":"Figure3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8599333/v1/ab2625e7978c857b718de80e.jpg"},{"id":101196089,"identity":"d6c138f3-467a-492b-9a20-c08ba2bffef8","added_by":"auto","created_at":"2026-01-27 08:12:32","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":181184,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic illustration of SHG spectroscopy. Inset: Top-view of the SEM image of plasmonic Al nanohole arrays with D = 480 nm and the schematic diagram of polarization-resolved SHG studies. [scale bar in inset is 500 nm] (b) A comparative study of SHG performances between hybrid MD arrays and bare Al films. (c) Power-dependent SHG measurements with a linear fitting with a slope of 1.93. (d) Polarization-resolved SHG measurements for hybrid MD arrays with different nanoholes’ diameters, i.e., D=480 nm, 550 nm, 600 nm, 680 nm, in which SHG intensities as a function of polarization angles of incident beams (varying from 0°to 360°with a step of 30°) are recorded. The data have been normalized, along with fitted curves shown as solid lines for observation.\u003c/p\u003e","description":"","filename":"Figure4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8599333/v1/8bfeeb17400236c8edfab833.jpg"},{"id":105754998,"identity":"a9fcd6f4-79fa-40ca-922d-191b963aa6de","added_by":"auto","created_at":"2026-03-30 16:24:00","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":958994,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8599333/v1/f7955bad-51b8-4eac-846e-35aa89e93687.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Expanding the hot-spot distribution in hybrid Nanohole Arrays toward high-performance light trapping","fulltext":[{"header":"1. INTRODUCTION","content":"\u003cp\u003eHigh efficiently manipulating the light and enhancing electromagnetic (EM) fields have emerged as a critical capability in numerous advanced applications, such as surface-enhanced Raman scattering (SERS) [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], surface-enhanced fluorescence (SEF) [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], nonlinear optics, and ultrasensitive sensors [\u003cspan additionalcitationids=\"CR6 CR7 CR8 CR9\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. The spatial position of enhanced EM fields commonly refers to as hot spots [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Traditionally, these hot spots are highly confined to extremely small scales, such as the gap between closely spaced nanoparticles or the sharp tip of plasmonic nanostructures [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Though these localized hot spots offer higher EM enhancements, the limitation of modal volumes often restricts the overall performance and scalability of nanophotonic devices. Expanding the modal volume of hot spots has become a vital strategy to elevate the performance of nanophotonic devices. By extending the distribution of hot spots, more molecules or fluorophores can interact with enhancement EM fields, thereby significantly improving the detection efficiency and signal-to-noise ratio in applications such as SERS and SEF. Several advanced strategies have been put forward to address these issues, for instance, optimizing structural design, engineering material, and introducing dielectric components that facilitate the redistribution of localized EM energies [\u003cspan additionalcitationids=\"CR14\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHere, we found that the mid-refractive-index Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric material can excite multipolar magnetic and electric resonances in the visible and near-infrared (NIR) regions [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Meanwhile, plasmonic aluminum (Al) material can support surface plasmonic resonances (SPRs) in a wide spectrum spanning ultraviolet (UV) to NIR regions [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. In this paper, we put forward a strategy of hybrid metal-dielectric (MD) nanohole arrays to realize trapping light, transferring energy and expanding the modal volume of hot spots at MD interfaces by introducing low-loss Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layers into Al nanohole arrays. Introduced dielectric-mediated plasmonic coupling facilitates the distribution of enhanced EM fields from visible to NIR regions (i.e., from 550 to 1000 nm). Theoretical and experimental results demonstrate that the EM energy is modulated from the air into the side wall of nanoholes as the thickness of Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer increases. The in-plane hot-spot distribution can be extended by changing the diameter of nanohole. Furthermore, the monolayer (1-L) MoS\u003csub\u003e2\u003c/sub\u003e deposited on plasmonic Al nanohole arrays with different diameters are used to perform photoluminescence (PL) signal, verifying that the plasmonic Al nanohole arrays with 480-nm diameter can obtain as high as 4-fold compared to that with 680-nm diameter. Meanwhile, we further investigate their performance as a nonlinear platform through plasmon-enhanced second-harmonic generation (PESHG), revealing that PESHG signals progressively decrease in the amplitude as Al nanohole diameters increases. These experimental results serve as both label and label-free optical probe to remotely monitor expanding regions of hot spots. Our work may provide a theoretical and experimental mechanism for realizing strong light-matter interaction.\u003c/p\u003e"},{"header":"2. EXPENRIMENTAL SECTION","content":"\u003cp\u003eIn this study, highly uniform hybrid MD arrays by integrating plasmonic Al nanohole arrays with Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer are fabricated by adopting nanosphere self-assembly technology combined with film depositing and reactive ion etching (RIE) techniques. Briefly, Al film with 100 nm thickness, as reflect films, is deposited onto the silicon substrate by means of electron beam film deposition system. Then, Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e film with 20-nm thickness is deposited onto the surface of Al film by means of plasma enhanced chemical vapor deposition (PECVD). Subsequently, the highly uniform polystyrene (PS) spheres with 750-nm diameter are hexagonal close-packed onto the surface of Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e film. The diameters of PSs can be modulated by varying the etch time in during of RIE. Finally, a 100-nm Al film is deposited onto the surface of prepared PS spheres. The adjustable Al nanohole arrays can be successfully obtained when the PS spheres are removed by utilizing lift-off technique. A schematic perspective view is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(a). The top-view scanning electron microscope (SEM) images in the Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(b) uncover that plasmonic Al nanohole arrays show high uniformity, which guarantees the repeatability and identity of signal acquisition. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e(c) displays the elements component of Al, silicon (Si), and oxygen (O) for large-scale sampled regions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"3. RESULTS AND DISCUSSION","content":"\u003cp\u003eWe theoretically investigate the thickness-dependent effect of the Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer on near and far-field characteristics, ranging from 0 nm to 110 nm with 20 nm increments. Simulated results demonstrate that the resonant peaks of absorption (A\u0026thinsp;=\u0026thinsp;1-R-T, T\u0026thinsp;=\u0026thinsp;0) occur evidently red shift from 650 nm to 860 nm, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(a). We can intuitively observe that the full width at half-maximum (FWHM) and near-field energy are influenced by the thickness of the Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(b). With the increase of the Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer, the FWHM is broadened from 33 nm to 183 nm and near-field energy exponential decay. To clearly represent the evolution of near-field energy densities, we provide the distribution of local EM field for the varied thickness of the Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(c). The TM polarized incident light is adopted at normal illumination (see the inset in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(a)). For the absence of Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e dielectric layer, the energy will be more dispersed into the free space. The resonant mode is mainly deriving from the located surface plasmon resonance (LSPR) generated by the corner of Al nanoholes. The distribution of near-field energy densities states that the Al nanoholes without dielectric layer can be considered as dispersive nanostructures. With the increase of dielectric-layer thicknesses, the distribution of near-field energy gradually transfers into the bottom layer and inner of Al nanoholes. For the case of 0-nm thickness dielectric layers, the line width is 33 nm and the electric-field strength is strongest at the upper and the vertical wall of Al nanoholes. When the thickness is increased to 100 nm, the near-field energy is almost squeezed into Al nanoholes. Meanwhile, the electric-field strength is concurrently weakened and FWHM is evidently broaden. In hybrid MD arrays, evaluating the strongest hot spots region as the near-field enhancement located at the corner of the Al nanoholes. When introducing dielectric layer, the near field is effectively modulated from the local region to the entire surface and bulk of the plasmonic Al nanohole arrays. The results provide theoretically foundation that the near-field energy can be modulated by the thickness of dielectric layer. Therefore, 20-nm thickness Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e film has been adopted to acted as dielectric layer for extending hot-spot distribution in plane.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eExperimentally, plasmonic Al nanohole arrays with 20-nm Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e layer have been manufactured to validate the modulation of near-field energy and the spatial distribution of hot spots region. The diameters of the plasmonic Al nanohole arrays can be adjusted by the etch time during RIE processes. Figure\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(a) shows the top-view SEM images of four samples with the same periodicity and different nanoholes\u0026rsquo; diameters, i.e., D\u0026thinsp;=\u0026thinsp;680 nm, 600 nm, 550 nm, and 480 nm. First, we theoretical and experimental investigate the effect of nanoholes\u0026rsquo; dimensions on the far-field optic characteristics and near-field energy distribution, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(b). The results demonstrate that the resonant peaks slightly blue shift and the FWHM is reduced as the decreasing of Al nanoholes diameters. The distributions of near-field energy indicate that the LSPR-excited energy is gradually dispersed to the free space with the increasing of Al nanohole diameters, and the ability of the energy localization is getting weakened. The simulation results are in agreement with the experimental results. Importantly, we offer the PL enhancement of MoS\u003csub\u003e2\u003c/sub\u003e to verify that near-field energy transfer from air layer to the inner of Al nanoholes. The plasmonic Al nanohole arrays, generating strong LSPR, can enhance the PL signal of 1-L MoS\u003csub\u003e2\u003c/sub\u003e. The MoS\u003csub\u003e2\u003c/sub\u003e transferred onto plasmonic Al nanohole arrays is first verified to be a monolayer by Raman spectroscopy, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(c) and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(d). The wave number spacing between the two modes, A\u003csub\u003e1g\u003c/sub\u003e and E\u003csub\u003e2g\u003c/sub\u003e\u003csup\u003e1\u003c/sup\u003e remains 18 cm\u003csup\u003e-1\u003c/sup\u003e after the transfer, which confirms that MoS\u003csub\u003e2\u003c/sub\u003e transferred onto plasmonic Al nanohole arrays is a monolayer [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan additionalcitationids=\"CR19\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Like the well-known Purcell effect [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], strong LSPR can change the local density of states of 1-L MoS\u003csub\u003e2\u003c/sub\u003e, which leads to additional emission pathways of MoS\u003csub\u003e2\u003c/sub\u003e and further enhances the PL signals. The PL signals show that plasmonic Al nanohole arrays with a diameter of 480 nm has better enhancement of PL signals, which is four times more than that of the nanohole with a diameter of 680 nm. Interestingly, the near-field energy also can be adjusted by controlling the nanoholes diameters.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eOne of primary applications benefiting from strong near-field energy confinements in plasmonic metasurfaces is nonlinear frequency conversion, where harmonic generation scales with the enhancement of local EM fields [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. To demonstrate the unique optical property of proposed configurations, we investigate their performance as a nonlinear platform for boosting the frequency conversion through second-harmonic generation (SHG). As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a), we introduce a laboratory-built SHG spectrometer to perform multiparameter-resolved measurements, including analyses of polarization dependence, geometrical influence, and incident power variation. These experiments aim to elucidate the amplification of nonlinear optical signals resulting from local-field enhancements near metallic nanohole elements. As anticipated, frequency-doubled emissions are observed in patterned samples [Figure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(b)], along with the measured SHG power emitted from nanohole arrays with D\u0026thinsp;=\u0026thinsp;480 nm exhibiting a quadratic dependence on pumping-laser powers [Figure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(c)], consistent with characteristic behaviors of SHG processes. Additionally, we discover that SHG signals emitted from proposed nanodevices greatly outperform those emitted from unpatterned metallic films [Figure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(b)]. These observations further confirm the efficient near-field energy confinement of patterned metallic counterparts. To verify this assumption, polarization-resolved measurements have been conducted as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(d). Considering that pumping-laser pulses propagate along the z axis, and the polarization orientation of incident beams can thus be defined by an azimuthal angle (α) with the y axis, ranging from 0\u0026deg; to 360\u0026deg; [see the inset of Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e(a)]. Experimental results reveal similar polar patterns across four cases with D\u0026thinsp;=\u0026thinsp;480 nm, 550 nm, 600 nm, and 680 nm, accompanied by a progressive decrease in the amplitude as D increases. This trend can be attributed to the influence of nanohole dimensions on near-field energy distributions, as previously illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e(b). In centrosymmetric plasmonic metals such as Al, second-order nonlinear responses primarily originate at interfaces [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Accordingly, we infer that retrieved SHG responses predominantly originate from the face-up surface of Al nanoholes. Furthermore, the vertically-aligned polarization moment exhibits rotational symmetry around the normal direction, consistent with the quasi-isotropic polarization dependence observed in SHG emission profiles [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Results mentioned above make feasible an ultrasensitive SHG probe of remotely monitoring the quantitative variation of local-field energy densities near the sidewall of nanoholes\u0026rsquo; elementary units [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4. CONSLUSION","content":"\u003cp\u003eIn conclusion, the hybrid MD arrays integrating metal nanohole arrays with dielectric layer have been successfully fabricated. The EM energy is modulated from the air into the inner of metal nanohole arrays and the hot spots region can be effectively extended by changing the thickness of dielectric layer and the diameters of metal nanohole arrays. The improved uniformity and extended hot spots region offer substantial benefits in various applications. The 1-L MoS\u003csub\u003e2\u003c/sub\u003e deposited on hybrid MD arrays with different diameters are used to perform PL signal and the results demonstrate that the plasmonic Al nanohole arrays with 480-nm diameter can obtain as high as 4-fold compared to that with 680-nm diameter. Furthermore, the experimental results of PESHG demonstrate that SHG signals emitted from proposed hybrid MD arrays and a progressive decrease in the amplitude as Al nanohole diameter increases. This work may provide a theoretical and experimental mechanism for expanding the potential in maneuvering light and extending hot spots region from surface enhancement to bulk phase modulation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData Availability Statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eData will be made available upon reasonable request.\u003c/p\u003e\n\u003cp\u003eAUTHOR INFORMATION\u003c/p\u003e\n\u003cp\u003eCorresponding Author\u003c/p\u003e\n\u003cp\u003eJ. Zheng-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China; orcid.org/0000-0002-5674-4979; Email: [email protected]\u003c/p\u003e\n\u003cp\u003eShao. X. Shen-College of Information Science and Engineering, Fujian Provincial Key laboratory of Light Propagation and Transformation, Huaqiao University, Xiamen 361021, China; Email: [email protected]\u003c/p\u003e\n\u003cp\u003eJian. Q. Zhu-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China; Email: [email protected]\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eShi. Y. Zhang-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China.\u003c/p\u003e\n\u003cp\u003eXiang. T. Xie- College of Information Science and Engineering, Fujian Provincial Key laboratory of Light Propagation and Transformation, Huaqiao University, Xiamen 361021, China.\u003c/p\u003e\n\u003cp\u003eC. Xie- College of Information Science and Engineering, Fujian Provincial Key laboratory of Light Propagation and Transformation, Huaqiao University, Xiamen 361021, China.\u003c/p\u003e\n\u003cp\u003eJun. J. Mao-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China.\u003c/p\u003e\n\u003cp\u003eYa. Y. Su-Key Laboratory of Micro-Nano Optoelectronic Materials and Devices at Sichuan Normal University of Sichuan Province, Chengdu 610101, China; College of Physics and Electronic Engineering, Sichuan Normal University, Chengdu 610101, China.\u003c/p\u003e\n\u003cp\u003eAuthor Contributions\u003c/p\u003e\n\u003cp\u003eJ.Z. and S.S.X.: Conceptualization, Methodology, Writing. S.Y.Z., X.X.T., and X.C.: Data curation, Investigation. J.J.M. and Y.R.S.: Visualization. J.Q.Z: Validation. J.Z. and S.S.X.: Supervision, Reviewing, Editing. \u0026dagger;Jie Zheng and Shiyu Zhang contributed equally to this work.\u003c/p\u003e\n\u003cp\u003eFunding Sources\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Natural Science Foundation of China (12104326, 12104329, and 12004121), Natural Science Foundation of Sichuan Province (2023NSFSC1305), Natural Science Foundation of Fujian Province (2024J01080); Fundamental Research Funds for the Central Universities (ZQN-1006).\u003c/p\u003e\n\u003cp\u003eNotes\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing financial interest.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eYi J, You EM, Hu R, Wu DY, Liu GK, Yang ZL, Zhang H, Gu Y, Wang YH, Wang X, Ma H, Yang Y, Liu JY, Fan FR, Zhan C, Tian JH, Qiao Y, Wang HL et al (2025) Surface-enhanced Raman spectroscopy: a half-century historical perspective. 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Opt Lett 48:1914\u0026ndash;1917\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"plasmonics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"plas","sideBox":"Learn more about [Plasmonics](https://www.springer.com/journal/11468)","snPcode":"11468","submissionUrl":"https://submission.nature.com/new-submission/11468/3","title":"Plasmonics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"plasmonic nanostructures, light trapping, plasmon-enhanced second-harmonic generation, surface-enhanced fluorescence, hybrid configurations","lastPublishedDoi":"10.21203/rs.3.rs-8599333/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8599333/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTrapping light and enhancing electromagnetic fields in plasmonic nanostructures are crucial for advanced applications, such as for surface-enhanced Raman scattering, surface-enhanced fluorescence and plasmon-enhanced second-harmonic generation (PESHG) at subwavelength scales. Expanding the spatial distribution of enhanced electromagnetic fields, i.e., hot spots, has become a vital strategy to significantly enhance the performance of advanced nanophotonic applications. In this work, we propose a strategy of hybrid metal-dielectric (MD) nanohole arrays by introducing low-loss silicon nitride (Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e) dielectric layers into aluminum (Al) nanohole arrays to realize the strong light-trapping and expand the spatial distribution of hot spots at MD interfaces by changing the diameter of nanohole. The mechanism governing these phenomena is deriving from the occurrence of dielectric-mediated plasmonic coupling, facilitating the translation of local light confinements governed by plasmon-driven resonances to dielectric components and LSPR-excited hot-spots redistribution in plane. Moreover, we introduce both label and label-free optical probes regarding the photoluminescence enhancement of MoS\u003csub\u003e2\u003c/sub\u003e and PESHG to verify and quantify the effect of expanded hot-spot distribution in hybrid Al-Si\u003csub\u003e3\u003c/sub\u003eN\u003csub\u003e4\u003c/sub\u003e nanohole arrays on the enhancement of light-matter interaction. This work may provide a theoretical and experimental mechanism for expanding the potential in characterizing and quantifying hot-spot distribution in advanced optical nanodevices.\u003c/p\u003e","manuscriptTitle":"Expanding the hot-spot distribution in hybrid Nanohole Arrays toward high-performance light trapping","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-27 08:12:27","doi":"10.21203/rs.3.rs-8599333/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-13T13:29:50+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-25T03:38:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"251711242470961619683345848658933372386","date":"2026-01-24T10:05:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"59469160829131416962542711017754014652","date":"2026-01-24T09:31:50+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-22T08:18:04+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-14T23:13:19+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-14T23:11:12+00:00","index":"","fulltext":""},{"type":"submitted","content":"Plasmonics","date":"2026-01-14T08:04:04+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"plasmonics","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"plas","sideBox":"Learn more about [Plasmonics](https://www.springer.com/journal/11468)","snPcode":"11468","submissionUrl":"https://submission.nature.com/new-submission/11468/3","title":"Plasmonics","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"285ddf86-f9f1-4d6f-9c7f-e951b19b7e0a","owner":[],"postedDate":"January 27th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-03-30T16:18:39+00:00","versionOfRecord":{"articleIdentity":"rs-8599333","link":"https://doi.org/10.1007/s11468-026-03351-x","journal":{"identity":"plasmonics","isVorOnly":false,"title":"Plasmonics"},"publishedOn":"2026-03-25 16:10:40","publishedOnDateReadable":"March 25th, 2026"},"versionCreatedAt":"2026-01-27 08:12:27","video":"","vorDoi":"10.1007/s11468-026-03351-x","vorDoiUrl":"https://doi.org/10.1007/s11468-026-03351-x","workflowStages":[]},"version":"v1","identity":"rs-8599333","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8599333","identity":"rs-8599333","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}