A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized...A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane（MPTS）. To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe3O4@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe3O4@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance（SPR） band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon（LSP） and the gap plasmon near-field coupling with the Fe3O4@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10^（-7） mol/L, and the Fe3O4@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe3O4@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.展开更多
Integration of multiple diversified functionalities into a single,planar and ultra-compact device has become an emerging research area with fascinating possibilities for realization of very dense integration and minia...Integration of multiple diversified functionalities into a single,planar and ultra-compact device has become an emerging research area with fascinating possibilities for realization of very dense integration and miniaturization in photonics that requires addressing formidable challenges,particularly for operation in the visible range.Here we design,fabricate and experimentally demonstrate bifunctional gap-plasmon metasurfaces for visible light,allowing for simultaneous polarization-controlled unidirectional surface plasmon polariton(SPP)excitation and beam steering at normal incidence.The designed bifunctional metasurfaces,consisting of anisotropic gap-plasmon resonator arrays,produce two different linear phase gradients along the same direction for respective linear polarizations of incident light,resulting in distinctly different functionalities realized by the same metasurface.The proof-of-concept fabricated metasurfaces exhibit efficient(425%on average)unidirectional(extinction ratio 420 dB)SPP excitation within the wavelength range of 600–650 nm when illuminated with normally incident light polarized in the direction of the phase gradient.At the same time,broadband(580–700 nm)beam steering(30.6°–37.9°)is realized when normally incident light is polarized perpendicularly to the phase gradient direction.The bifunctional metasurfaces developed in this study can enable advanced research and applications related to other distinct functionalities for photonics integration.展开更多
Monolayer transition-metal dichalcogenides（TMDs） have attracted a lot of attention for their applications in optics and optoelectronics.Molybdenum disulfide（MoS2）,as one of those important materials,has been widel...Monolayer transition-metal dichalcogenides（TMDs） have attracted a lot of attention for their applications in optics and optoelectronics.Molybdenum disulfide（MoS2）,as one of those important materials,has been widely investigated due to its direct band gap and photoluminescence（PL） in visible range.Owing to the fact that the monolayer MoS2 suffers low light absorption and emission,surface plasmon polaritons（SPPs） are used to enhance both the excitation and emission efficiencies.Here,we demonstrate that the PL of MoS2 sandwiched between 200-nm-diameter gold nanoparticle（Au NP） and 150-nm-thick gold film is improved by more than 4 times compared with bare MoS2 sample.This study shows that gap plasmons can possess more optical and optoelectronic applications incorporating with many other emerging two-dimensional materials.展开更多
The engineering of self-organized plasmonic metasurfaces is demonstrated using a maskless technique with defocused ion-beam sputtering and kinetically controlled deposition. The proposed reliable, cost-effective, and ...The engineering of self-organized plasmonic metasurfaces is demonstrated using a maskless technique with defocused ion-beam sputtering and kinetically controlled deposition. The proposed reliable, cost-effective, and controllable approach enables large-area （order of square centimeter） sub-wavelength periodic patterning with close-packed gold nanostrips. A multi-level variant of the method leads to high-resolution manufacturing of vertically stacked nanostrip dimer arrays, without resorting to lithographic approaches. The design of these self-organized metasurfaces is optimized by employing plasmon hybridization methods. In particular, preliminary results on the so-called gap-plasmon configuration of the nanostrip dimers, implementing magnetic dipole resonance in the near-infrared range, are reported. This resonance offers a superior sensitivity and field enhancement, compared with the more conventional electric dipole resonance. The translational invariance of the nanostrip configuration leads to a high filling factor of the hot spots. These advanced features make the large-area metasurface based on gap-plasmon nanostrip dimers very attractive for surface-enhanced linear and nonlinear spectroscopy （e.g., surface-enhanced Raman scattering） and plasmon-enhanced photon harvesting in solar and photovoltaic cells.展开更多
Creating nanoscale and sub-nanometer gaps between noble metal nanoparticles is critical for the applications of plasmonics and nanophotonics. To realize simultaneous attainments of both the op- tical spectrum and the ...Creating nanoscale and sub-nanometer gaps between noble metal nanoparticles is critical for the applications of plasmonics and nanophotonics. To realize simultaneous attainments of both the op- tical spectrum and the gap size, the ability to tune these nanoscale gaps at the sub-nanometer scale is particularly desirable. Many nanofabrication methodologies, including electron beam lithography, self-assembly, and focused ion beams, have been tested for creating nanoscale gaps that can de- liver significant field enhancement. Here, we survey recent progress in both the reliable creation of nanoscale gaps in nanoparticle arrays using self-assemblies and in the in-situ tuning techniques at the sub-nanometer scale. Precisely tunable gaps, as we expect, will be good candidates for future investigations of surface-enhanced Raman scattering, non-linear optics, and quantum plasmonics.展开更多
基金Funded by the National Natural Science Foundation of China(NSFC)(Nos.51273048 and 51203025)the Natural Science Foundation of Guangdong Province(No.S2012040007725)
文摘A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B（RB） was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane（MPTS）. To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe3O4@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe3O4@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance（SPR） band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon（LSP） and the gap plasmon near-field coupling with the Fe3O4@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10^（-7） mol/L, and the Fe3O4@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe3O4@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.
基金the financial support from the European Research Council,Grant 341054(PLAQNAP)the University of Southern Denmark(SDU 2020).
文摘Integration of multiple diversified functionalities into a single,planar and ultra-compact device has become an emerging research area with fascinating possibilities for realization of very dense integration and miniaturization in photonics that requires addressing formidable challenges,particularly for operation in the visible range.Here we design,fabricate and experimentally demonstrate bifunctional gap-plasmon metasurfaces for visible light,allowing for simultaneous polarization-controlled unidirectional surface plasmon polariton(SPP)excitation and beam steering at normal incidence.The designed bifunctional metasurfaces,consisting of anisotropic gap-plasmon resonator arrays,produce two different linear phase gradients along the same direction for respective linear polarizations of incident light,resulting in distinctly different functionalities realized by the same metasurface.The proof-of-concept fabricated metasurfaces exhibit efficient(425%on average)unidirectional(extinction ratio 420 dB)SPP excitation within the wavelength range of 600–650 nm when illuminated with normally incident light polarized in the direction of the phase gradient.At the same time,broadband(580–700 nm)beam steering(30.6°–37.9°)is realized when normally incident light is polarized perpendicularly to the phase gradient direction.The bifunctional metasurfaces developed in this study can enable advanced research and applications related to other distinct functionalities for photonics integration.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61590932 and 11774333)the Anhui Initiative Project in Quantum Information Technologies,China(Grant No.AHY130300)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB24030600)the National Key Research and Development Program of China(Grant No.2016YFA0301700)the Fundamental Research Funds for the Central Universities,China
文摘Monolayer transition-metal dichalcogenides（TMDs） have attracted a lot of attention for their applications in optics and optoelectronics.Molybdenum disulfide（MoS2）,as one of those important materials,has been widely investigated due to its direct band gap and photoluminescence（PL） in visible range.Owing to the fact that the monolayer MoS2 suffers low light absorption and emission,surface plasmon polaritons（SPPs） are used to enhance both the excitation and emission efficiencies.Here,we demonstrate that the PL of MoS2 sandwiched between 200-nm-diameter gold nanoparticle（Au NP） and 150-nm-thick gold film is improved by more than 4 times compared with bare MoS2 sample.This study shows that gap plasmons can possess more optical and optoelectronic applications incorporating with many other emerging two-dimensional materials.
文摘The engineering of self-organized plasmonic metasurfaces is demonstrated using a maskless technique with defocused ion-beam sputtering and kinetically controlled deposition. The proposed reliable, cost-effective, and controllable approach enables large-area （order of square centimeter） sub-wavelength periodic patterning with close-packed gold nanostrips. A multi-level variant of the method leads to high-resolution manufacturing of vertically stacked nanostrip dimer arrays, without resorting to lithographic approaches. The design of these self-organized metasurfaces is optimized by employing plasmon hybridization methods. In particular, preliminary results on the so-called gap-plasmon configuration of the nanostrip dimers, implementing magnetic dipole resonance in the near-infrared range, are reported. This resonance offers a superior sensitivity and field enhancement, compared with the more conventional electric dipole resonance. The translational invariance of the nanostrip configuration leads to a high filling factor of the hot spots. These advanced features make the large-area metasurface based on gap-plasmon nanostrip dimers very attractive for surface-enhanced linear and nonlinear spectroscopy （e.g., surface-enhanced Raman scattering） and plasmon-enhanced photon harvesting in solar and photovoltaic cells.
基金supported by the National Key R&D Program of China (2016YFA0301300)the National Natural Science Foundation of China (11974437 and 91750207)+6 种基金the Key-Area Research and Development Program of Guangdong Province (2018B030329001)Guangdong Special Support Program (2017TQ04C487)Guangdong Natural Science Funds for Distinguished Young Scholars (2017B030306007)Guangdong Natural Science Funds (2020A0505140004)Pearl River S&T Nova Program of Guangzhou (201806010033)the Open Fund of IPOC (BUPT) (IPOC2019A003)the Fundamental Research Funds for the Central Universities (20lgzd30)。
文摘Creating nanoscale and sub-nanometer gaps between noble metal nanoparticles is critical for the applications of plasmonics and nanophotonics. To realize simultaneous attainments of both the op- tical spectrum and the gap size, the ability to tune these nanoscale gaps at the sub-nanometer scale is particularly desirable. Many nanofabrication methodologies, including electron beam lithography, self-assembly, and focused ion beams, have been tested for creating nanoscale gaps that can de- liver significant field enhancement. Here, we survey recent progress in both the reliable creation of nanoscale gaps in nanoparticle arrays using self-assemblies and in the in-situ tuning techniques at the sub-nanometer scale. Precisely tunable gaps, as we expect, will be good candidates for future investigations of surface-enhanced Raman scattering, non-linear optics, and quantum plasmonics.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （No. 21273092） and the National Basic Research Program of China （No. 2009CB939701）.
