Cavity-coupled plasmonic structure is demonstrated to be a simple and effective tool to manipulatelight,enhance the biosensing figure of merit, and control the polarization state. In this Letter, we demonstrate the tu...Cavity-coupled plasmonic structure is demonstrated to be a simple and effective tool to manipulatelight,enhance the biosensing figure of merit, and control the polarization state. In this Letter, we demonstrate the tunability of the chiroptical effect of cavity-coupled chiral structure, i.e., sandwich chiral metamaterials（SCMs）, in whichradiation coupling dominates the interaction between particles. Two types of SCMs whose building blocks are 3D chiral and 2D chiral, respectively, are numerically studied. Distinct responses are observed in these two materials. The chiroptical effect can be effectively manipulated and enhanced in the 2D case, while the SCMs consisting of 3D chiral layers keep the chiroptical effecta constant. A theoretical analysis based on matrix optics is developed to explain the corresponding phenomena, which gives a reasonable agreement with numerical simulations.展开更多
Plasmonic structural colors have plenty of advantages over traditional colors based on colorants.The pulsed laser provides an important method generating plasmonic structural colors with high efficiency and low cost.H...Plasmonic structural colors have plenty of advantages over traditional colors based on colorants.The pulsed laser provides an important method generating plasmonic structural colors with high efficiency and low cost.Here,we present plasmonic color printing Al nanodisc structures through curvature-driven shape transition.We systematically study the mechanism of morphologic evolution of the Al nanodisc below the thermal melting threshold.A multi-pulse-induced accumulated photothermal effect and subsequent curvature-driven surface atom diffusion model are adopted to explain the controllable shape transition.The shape transition and corresponding plasmonic resonances of the nanodisc can be independently and precisely modulated by controlled irradiations.This method opens new ways towards high-fidelity color prints in a highly efficient and facile laser writing fashion.展开更多
The circular dichroism（CD） signal of a two-dimensional（2D） chiral meta-surface is usually weak, where the difference between the transmitted（or reflected） right and left circular polarization is barely small. We...The circular dichroism（CD） signal of a two-dimensional（2D） chiral meta-surface is usually weak, where the difference between the transmitted（or reflected） right and left circular polarization is barely small. We present a general method to enhance the reflective CD spectrum, by adding a layer of reflective film behind the meta-surface. The light passes through the chiral meta-surface and propagates towards the reflector, where it is reflected back and further interacts with the chiral meta-surface. The light is reflected back and forth between these two layers, forming a Fabry–Perot type resonance,which interacts with the localized surface plasmonic resonance（LSPR） mode and greatly enhances the CD signal of the light wave leaving the meta-surface. We numerically calculate the CD enhancing effect of an L-shaped chiral meta-surface on a gold film in the visible range. Compared with the single layer meta-surface, the L-shaped chiral meta-surface has a CD maximum that is dramatically increased to 1. The analysis of reflection efficiency reveals that our design can be used to realize a reflective circular polarizer. Corresponding mode analysis shows that the huge CD originates from the hybrid mode comprised of FP mode and LSPR. Our results provide a general approach to enhancing the CD signal of a chiral meta-surface and can be used in areas like biosensing, circular polarizer, integrated photonics, etc.展开更多
We present a narrow band forward scattering optical antenna which is based on the excitation of distinctive whispering gallery modes（WGMs）. The antenna is composed of three coaxial cylinder layers： a dielectric lay...We present a narrow band forward scattering optical antenna which is based on the excitation of distinctive whispering gallery modes（WGMs）. The antenna is composed of three coaxial cylinder layers： a dielectric layer is sandwiched between a metallic core and cladding. Owing to the destructive interference between the scattering of the outer metallic cladding and the WGM in the backward direction, the power flow in the forward direction is increased. Simulation and analysis show that in proper geometry conditions, the cavity can be tuned into a superscattering state. At this state, both the zeroth and the first order of WGM are excited and contribute to the total scattering. It is shown that the power ratio（power towards backward divided by power towards forward） can be enhanced to about 27 times larger than that for a non-resonant position by the superscattering. Owing to the confinement of the cladding to WGMs, the wavelength range of effective forward scattering is considerably narrow（about 15 nm）.展开更多
基金supported by the National Natural Science Foundation of China under Grant No.61377054
文摘Cavity-coupled plasmonic structure is demonstrated to be a simple and effective tool to manipulatelight,enhance the biosensing figure of merit, and control the polarization state. In this Letter, we demonstrate the tunability of the chiroptical effect of cavity-coupled chiral structure, i.e., sandwich chiral metamaterials（SCMs）, in whichradiation coupling dominates the interaction between particles. Two types of SCMs whose building blocks are 3D chiral and 2D chiral, respectively, are numerically studied. Distinct responses are observed in these two materials. The chiroptical effect can be effectively manipulated and enhanced in the 2D case, while the SCMs consisting of 3D chiral layers keep the chiroptical effecta constant. A theoretical analysis based on matrix optics is developed to explain the corresponding phenomena, which gives a reasonable agreement with numerical simulations.
基金the National Key R&D Program of China(No.YS2018YFB110012)the Guangdong Provincial Innovation and Entrepreneurship Project(No.2016ZT06D081)。
文摘Plasmonic structural colors have plenty of advantages over traditional colors based on colorants.The pulsed laser provides an important method generating plasmonic structural colors with high efficiency and low cost.Here,we present plasmonic color printing Al nanodisc structures through curvature-driven shape transition.We systematically study the mechanism of morphologic evolution of the Al nanodisc below the thermal melting threshold.A multi-pulse-induced accumulated photothermal effect and subsequent curvature-driven surface atom diffusion model are adopted to explain the controllable shape transition.The shape transition and corresponding plasmonic resonances of the nanodisc can be independently and precisely modulated by controlled irradiations.This method opens new ways towards high-fidelity color prints in a highly efficient and facile laser writing fashion.
基金supported by the National Natural Science Foundation of China(Grant No.61377054)
文摘The circular dichroism（CD） signal of a two-dimensional（2D） chiral meta-surface is usually weak, where the difference between the transmitted（or reflected） right and left circular polarization is barely small. We present a general method to enhance the reflective CD spectrum, by adding a layer of reflective film behind the meta-surface. The light passes through the chiral meta-surface and propagates towards the reflector, where it is reflected back and further interacts with the chiral meta-surface. The light is reflected back and forth between these two layers, forming a Fabry–Perot type resonance,which interacts with the localized surface plasmonic resonance（LSPR） mode and greatly enhances the CD signal of the light wave leaving the meta-surface. We numerically calculate the CD enhancing effect of an L-shaped chiral meta-surface on a gold film in the visible range. Compared with the single layer meta-surface, the L-shaped chiral meta-surface has a CD maximum that is dramatically increased to 1. The analysis of reflection efficiency reveals that our design can be used to realize a reflective circular polarizer. Corresponding mode analysis shows that the huge CD originates from the hybrid mode comprised of FP mode and LSPR. Our results provide a general approach to enhancing the CD signal of a chiral meta-surface and can be used in areas like biosensing, circular polarizer, integrated photonics, etc.
基金Project supported by the National Natural Science Foundation of China(Grant No.61377054)the Collaborative Innovation Foundation of Sichuan University,China(Grant No.XTCX 2013002)the International Cooperation and Exchange of Science and Technology Project in Sichuan Province,China(Grant No.2013HH0010)
文摘We present a narrow band forward scattering optical antenna which is based on the excitation of distinctive whispering gallery modes（WGMs）. The antenna is composed of three coaxial cylinder layers： a dielectric layer is sandwiched between a metallic core and cladding. Owing to the destructive interference between the scattering of the outer metallic cladding and the WGM in the backward direction, the power flow in the forward direction is increased. Simulation and analysis show that in proper geometry conditions, the cavity can be tuned into a superscattering state. At this state, both the zeroth and the first order of WGM are excited and contribute to the total scattering. It is shown that the power ratio（power towards backward divided by power towards forward） can be enhanced to about 27 times larger than that for a non-resonant position by the superscattering. Owing to the confinement of the cladding to WGMs, the wavelength range of effective forward scattering is considerably narrow（about 15 nm）.
