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
The strong chiroptical effect is highly desirable and has a wide range of applications in biosensing, chiral catalysis,polarization tuning, and chiral photo detection. In this work, we find a simple method to enhance ...The strong chiroptical effect is highly desirable and has a wide range of applications in biosensing, chiral catalysis,polarization tuning, and chiral photo detection. In this work, we find a simple method to enhance the reflection circular dichroism(CDR) by placing the planar anisotropic chiral metamaterials(i.e., Z-shaped PACMs) on the interface of two media(i.e., Z-PCMI) with a large refractive index difference. The maximum reflection CDR from the complex system can reach about 0.840 when the refractive index is set as ntop = 4.0 and nbottom = 1.49, which is approximately three times larger than that of placing the Z-shaped PACMs directly on the substrate(i.e., Z-PCMS). While the minimum reflection CDR is 0.157 when the refractive index is set as ntop = 1.0 and nbottom = 1.49. So we can get a large available range of reflection CDR from -0.840 to -0.157. Meanwhile, the transmission CDT remains unchanged with the refractive index ntop increment. Our in-depth research indicates that the large reflection CDR is derived from the difference of non-conversion components of the planar anisotropic chiral metamaterials’ reflection matrices. In short, we provide a simple and practical method to enhance the chiroptical effect by changing the refractive index difference between two media without having to design a complex chiral structure.展开更多
High performance optical diode-like devices are highly desired in future practical nano-photonic devices with strong directional selectivity.We demonstrate a kind of giant broadband reciprocity optical diode-like devi...High performance optical diode-like devices are highly desired in future practical nano-photonic devices with strong directional selectivity.We demonstrate a kind of giant broadband reciprocity optical diode-like devices by simultaneously using the directional Mie scattering effect and the asymmetric grating diffraction effect.The maximum asymmetric subtraction and the asymmetric transmission ratio can reach nearly 100%and 40dB at specified wavelength,respectively.In a wide waveband from 500nm to 800nm,the asymmetric subtraction and the ratio keep larger than 80%and 3.5 dB,respectively,even under oblique incidence.To the best of our knowledge,this is the best one-way-transmission effect observed in the reciprocity optical diode-like devices.In addition,we further demonstrate that this one-way-transmission effect can bring an effective absorption enhancement on gold films.The giant,broadband and angle-insensitive one-way-transmission effect demonstrated here is far beyond the well-known anti-reflection effect in the light-trapping devices and will bring new design philosophy for nano-photonic devices.展开更多
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
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. 11604227).
文摘The strong chiroptical effect is highly desirable and has a wide range of applications in biosensing, chiral catalysis,polarization tuning, and chiral photo detection. In this work, we find a simple method to enhance the reflection circular dichroism(CDR) by placing the planar anisotropic chiral metamaterials(i.e., Z-shaped PACMs) on the interface of two media(i.e., Z-PCMI) with a large refractive index difference. The maximum reflection CDR from the complex system can reach about 0.840 when the refractive index is set as ntop = 4.0 and nbottom = 1.49, which is approximately three times larger than that of placing the Z-shaped PACMs directly on the substrate(i.e., Z-PCMS). While the minimum reflection CDR is 0.157 when the refractive index is set as ntop = 1.0 and nbottom = 1.49. So we can get a large available range of reflection CDR from -0.840 to -0.157. Meanwhile, the transmission CDT remains unchanged with the refractive index ntop increment. Our in-depth research indicates that the large reflection CDR is derived from the difference of non-conversion components of the planar anisotropic chiral metamaterials’ reflection matrices. In short, we provide a simple and practical method to enhance the chiroptical effect by changing the refractive index difference between two media without having to design a complex chiral structure.
基金Supported by the National Natural Science Foundation of China under Grant No.11604227。
文摘High performance optical diode-like devices are highly desired in future practical nano-photonic devices with strong directional selectivity.We demonstrate a kind of giant broadband reciprocity optical diode-like devices by simultaneously using the directional Mie scattering effect and the asymmetric grating diffraction effect.The maximum asymmetric subtraction and the asymmetric transmission ratio can reach nearly 100%and 40dB at specified wavelength,respectively.In a wide waveband from 500nm to 800nm,the asymmetric subtraction and the ratio keep larger than 80%and 3.5 dB,respectively,even under oblique incidence.To the best of our knowledge,this is the best one-way-transmission effect observed in the reciprocity optical diode-like devices.In addition,we further demonstrate that this one-way-transmission effect can bring an effective absorption enhancement on gold films.The giant,broadband and angle-insensitive one-way-transmission effect demonstrated here is far beyond the well-known anti-reflection effect in the light-trapping devices and will bring new design philosophy for nano-photonic devices.
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.
