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Metamaterials and metasurfaces for designing metadevices:Perfect absorbers and microstrip patch antennas 被引量:2
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作者 Yahong Liu Xiaopeng Zhao 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第11期235-249,共15页
In the past twenty years, electromagnetic metamaterials represented by left-handed metamaterials(LHMs) have attracted considerable attention due to the unique properties such as negative refraction, perfect lens, an... In the past twenty years, electromagnetic metamaterials represented by left-handed metamaterials(LHMs) have attracted considerable attention due to the unique properties such as negative refraction, perfect lens, and electromagnetic cloaks. In this paper, we present a comprehensive review of our group's work on metamaterials and metasurfaces. We present several types of LHMs and chiral metamaterials. As a two-dimensional equivalent of bulk three-dimensional metamaterials, metasurfaces have led to a myriad of devices due to the advantages of lower profile, lower losses, and simpler to fabricate than bulk three-dimensional metamaterials. We demonstrate the novel microwave metadevices based on metamaterials and metasurfaces: perfect absorbers and microwave patch antennas, including novel transmission line antennas,high gain resonant cavity antennas, wide scanning phased array antennas, and circularly polarized antennas. 展开更多
关键词 left-handed metamaterials chiral metamaterials metasurfaces perfect absorbers microstrip patch antennas
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Achieving a multi-band metamaterial perfect absorber via a hexagonal ring dielectric resonator
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作者 李立扬 王军 +2 位作者 杜红亮 王甲富 屈绍波 《Chinese Physics B》 SCIE EI CAS CSCD 2015年第6期314-320,共7页
A multi-band absorber composed of high-permittivity hexagonal ring dielectric resonators and a metallic ground plate is designed in the microwave band. Near-unity absorptions around 9.785 GHz, 11.525 GHz, and 12.37 GH... A multi-band absorber composed of high-permittivity hexagonal ring dielectric resonators and a metallic ground plate is designed in the microwave band. Near-unity absorptions around 9.785 GHz, 11.525 GHz, and 12.37 GHz are observed for this metamaterial absorber. The dielectric hexagonal ring resonator is made of microwave ceramics with high permittivity and low loss. The mechanism for the near-unity absorption is investigated via the dielectric resonator theory. It is found that the absorption results from electric and magnetic resonances where enhanced electromagnetic fields are excited inside the dielectric resonator. In addition, the resonance modes of the hexagonal resonator are similar to those of standard rectangle resonators and can be used for analyzing hexagonal absorbers. Our work provides a new research method as well as a solid foundation for designing and analyzing dielectric metamaterial absorbers with complex shapes. 展开更多
关键词 MULTI-BAND perfect absorber all-dielectric METAMATERIAL
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Nonlinear coherent perfect photon absorber in asymmetrical atom–nanowires coupling system
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作者 Xiuwen Xia Xinqin Zhang +2 位作者 Jingping Xu Mutian Cheng Yaping Yang 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第11期494-497,共4页
Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perf... Coherent perfect absorption provides a method of light-controlling-light and has practical applications in optical communications. Recently, a cavity-based nonlinear perfect photon absorption extends the coherent perfect absorber(CPA)beyond the linear regime. As nanowire-based system is a more competitive candidate for full-optical device, we introduce a nonlinear CPA in the single two-level atom–nanowires coupling system in this work. Nonlinear input–output relations are derived analytically, and three contributions of atomic saturation nonlinearity are explicit. The consociation of optical nonlinearity and destructive interference makes it feasible to fabricate a nonlinear monoatomic CPA. Our results also indicate that a nonlinear system may work linearly even when the incoming lights are not weak any more. Our findings show promising applications in full-optical devices. 展开更多
关键词 single-atom system atom-nanowires coupling nonlinear coherent perfect absorber
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Narrowband perfect terahertz absorber based on polar-dielectrics metasurface
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作者 Meng-Meng Zhao Shu-Fang Fu +7 位作者 Sheng Zhou Yu-Ling Song Qiang Zhang Yong-Qi Yin Yu-Tian Zhao Hong Liang Xuan-Zhang Wang 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第5期297-302,共6页
We theoretically propose a narrowband perfect absorber metasurface(PAMS) based on surface phonon polaritons in the terahertz range. The PAMS has unit cell consisting of a silver biarc on the top, a thin polar-dielectr... We theoretically propose a narrowband perfect absorber metasurface(PAMS) based on surface phonon polaritons in the terahertz range. The PAMS has unit cell consisting of a silver biarc on the top, a thin polar-dielectric in the middle and a silver layer at the bottom. The phonon polaritons are excited at the interface between the silver biarc and the polar dielectric, and enhance the absorption of the PAMS. The absorption peak is at 36.813 μm and the full width half maximum(FWHM) is nearly 36 nm, independent of the polarization and incidence angle. The electric fields are located at the split of the biarc silver layer and the quality factor Q is 1150. The FWHM decreases with the decreasing split width. When the thickness of the bottom layer is larger than 50 nm, the narrow band and high absorption are insensitive to the thickness of those layers. The designed absorber may have useful applications in terahertz spectra such as energy harvesting, thermal emitter, and sensing. 展开更多
关键词 metasurface narrowband perfect absorber TERAHERTZ polar-dielectrics
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Terahertz Perfect Absorber Based on Asymmetric Open-Loop Cross-Dipole Structure
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作者 Meng-Yao Yan Bi-Jun Xu +2 位作者 Zhi-Chao Sun Zhen-Dong Wu Bai-Rui Wu 《Chinese Physics Letters》 SCIE CAS CSCD 2020年第6期94-97,共4页
Equipped with multiple and unique features,a terahertz absorber exhibits great potential for use in the development of communication,military,and other fields where achieving perfect broadband absorption has always be... Equipped with multiple and unique features,a terahertz absorber exhibits great potential for use in the development of communication,military,and other fields where achieving perfect broadband absorption has always been a challenge.We present a metamaterial terahertz(THz)absorber comprising a cross-dipole patch,four symmetric square patches and an asymmetric open-loop patch with a good perfect absorption rate for TE and TM polarizations.The average absorption of more than 96%occurs in the frequency range from 2.4 THz to3.8 THz,in which the absorptance peak can reach 99.9%,as indicated by simulated results.Our design has broad potential applications in THz couplers,as well as in fields like biology and security. 展开更多
关键词 absorber ABSORPTION perfect
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Nearly Perfect Absorbers Operating Associated with Fano Resonance in the Infrared Range
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作者 黄万霞 赵国任 +2 位作者 郭娟娟 汪茂胜 石建平 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第8期131-134,共4页
We fabricate a three-layer metamaterial of metal patterns/dielectric/metal films. The optical properties associated with Fano resonance of the metamaterials are investigated experimentally and theoretically. The resul... We fabricate a three-layer metamaterial of metal patterns/dielectric/metal films. The optical properties associated with Fano resonance of the metamaterials are investigated experimentally and theoretically. The results indicate that the introduction of Fano resonance due to symmetry breaking leads to a much wider absorption range. Furthermore, the amplitude and phase of reflection can be modulated effectively by adjusting various free parameters using the proposed structure. 展开更多
关键词 with or on of Nearly perfect absorbers Operating Associated with Fano Resonance in the Infrared Range in MODE is
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Solar broadband metamaterial perfect absorber based on dielectric resonant structure of Ge cone array and InAs film
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作者 Kuang-Ling Guo Hou-Hong Chen +2 位作者 Xiao-Ming Huang Tian-Hui Hu Hai-Ying Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第11期325-330,共6页
The broadband metamaterial perfect absorber has been extensively studied due to its excellent characteristics and promising application prospect.In this work a solar broadband metamaterial perfect absorber is proposed... The broadband metamaterial perfect absorber has been extensively studied due to its excellent characteristics and promising application prospect.In this work a solar broadband metamaterial perfect absorber is proposed based on the structure of the germanium(Ge)cone array and the indium arsenide(InAs)dielectric film on the gold(Au)substrate.The results show that the absorption covers the whole ultraviolet-visible and near-infrared range.For the case of A>99%,the absorption bandwidth reaches up to 1230 nm with a wavelength range varied from 200 nm to 1430 nm.The proposed absorber is able to absorb more than 98.7%of the solar energy in a solar spectrum from 200 nm to 3000 nm.The electromagnetic dipole resonance and the high-order modes of the Ge cone couple strongly to the incident optical field,which introduces a strong coupling with the solar radiation and produces an ultra-broadband absorption.The absorption spectrum can be feasibly manipulated via tuning the structural parameters,and the polarization insensitivity performance is particularly excellent.The proposed absorber can possess wide applications in active photoelectric effects,thermion modulators,and photoelectric detectors. 展开更多
关键词 METAMATERIAL electromagnetic resonance perfect absorber solar broadband absorption`
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A three-band perfect absorber based on a parallelogram metamaterial slab with monolayer MoS_(2)
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作者 张雯婧 刘青松 +3 位作者 程波 晁明豪 徐云 宋国峰 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第3期280-285,共6页
As a two-dimensional(2D)material,monolayer MoS2which limits its optical applications has a low absorption efficiency.In this paper,we propose a three-band perfect metamaterial absorber in the visible light range based... As a two-dimensional(2D)material,monolayer MoS2which limits its optical applications has a low absorption efficiency.In this paper,we propose a three-band perfect metamaterial absorber in the visible light range based on monolayer MoS_(2).The peak absorptivity of the structure at each resonance wavelength is nearly perfect,moreover,the light absorption of monolayer MoS2is obviously enhanced at the three resonant wavelengths.The dielectric–dielectric–metal structure we designed produces the coupling of Fabry–Perot resonance and high-order diffraction guided-mode resonance at different absorption peaks,which has been proved by the slab waveguide theory.In addition,the multi-modal absorption phenomenon is explained by extracting the equivalent impedance.The results show that we can adjust the absorption peak wavelength by regulating the parameters of the structure.This structure not only provides an idea for enhancing the interaction between light and two-dimensional materials but also has potential applications for optical detection devices. 展开更多
关键词 METAMATERIAL perfect absorber monolayer MoS_(2) high-order diffraction
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A Perfect Graphene Absorber with Waveguide Coupled High-Contrast Gratings
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作者 张皓景 郑改革 +2 位作者 陈云云 邹秀娟 徐林华 《Chinese Physics Letters》 SCIE CAS CSCD 2018年第3期101-105,共5页
To achieve the enhancement and manipulation of light absorption in graphene within the visible and near infrared regions, a design consists of high-contrast gratings and two evanescently coupled slabs with graphene mo... To achieve the enhancement and manipulation of light absorption in graphene within the visible and near infrared regions, a design consists of high-contrast gratings and two evanescently coupled slabs with graphene monolayer is demonstrated. The operation principle and design process of the proposed structure are analyzed using the coupled mode theory, which is confirmed by the rigorous coupled wave analysis. It is proved that the absorptance of graphene monolayer can be greatly enhanced to unity. The thickness of grating and slab layers can significantly change the line width and resonant mode position in the absorption spectra. Furthermore, high tunability in amplitude and bandwidth of the absorption spectra can be achieved by controlling the structural parameters of the hybrid structure. The proposed devices could be efficiently exploited as tunable and selective absorbers, and could be allowed to realize other two-dimensional materials-based selective photo-detectors. 展开更多
关键词 A perfect Graphene absorber with Waveguide Coupled High-Contrast Gratings
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Perfectly matched layer-absorbing boundary condition for finite-element time-domain modeling of elastic wave equations 被引量:3
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作者 赵建国 史瑞其 《Applied Geophysics》 SCIE CSCD 2013年第3期323-336,359,共15页
The perfectly matched layer (PML) is a highly efficient absorbing boundary condition used for the numerical modeling of seismic wave equation. The article focuses on the application of this technique to finite-eleme... The perfectly matched layer (PML) is a highly efficient absorbing boundary condition used for the numerical modeling of seismic wave equation. The article focuses on the application of this technique to finite-element time-domain numerical modeling of elastic wave equation. However, the finite-element time-domain scheme is based on the second- order wave equation in displacement formulation. Thus, the first-order PML in velocity-stress formulation cannot be directly applied to this scheme. In this article, we derive the finite- element matrix equations of second-order PML in displacement formulation, and accomplish the implementation of PML in finite-element time-domain modeling of elastic wave equation. The PML has an approximate zero reflection coefficients for bulk and surface waves in the finite-element modeling of P-SV and SH wave propagation in the 2D homogeneous elastic media. The numerical experiments using a two-layer model with irregular topography validate the efficiency of PML in the modeling of seismic wave propagation in geological models with complex structures and heterogeneous media. 展开更多
关键词 absorbing boundary condition elastic wave equation perfectly matched layer finite-element modeling
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The Application of the Nonsplitting Perfectly Matched Layer in Numerical Modeling of Wave Propagation in Poroelastic Media 被引量:4
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作者 宋若龙 马俊 王克协 《Applied Geophysics》 SCIE CSCD 2005年第4期216-222,共7页
The nonsplitting perfectly matched layer (NPML) absorbing boundary condition (ABC) was first provided by Wang and Tang (2003) for the finite-difference simulation of elastic wave propagation in solids. In this p... The nonsplitting perfectly matched layer (NPML) absorbing boundary condition (ABC) was first provided by Wang and Tang (2003) for the finite-difference simulation of elastic wave propagation in solids. In this paper, the method is developed to extend the NPML to simulating elastic wave propagation in poroelastic media. Biot's equations are discretized and approximated to a staggered-grid by applying a fourth-order accurate central difference in space and a second-order accurate central difference in time. A cylindrical twolayer seismic model and a borehole model are chosen to validate the effectiveness of the NPML. The results show that the numerical solutions agree well with the solutions of the discrete wavenumber (DW) method. 展开更多
关键词 FINITE-DIFFERENCE numerical simulation absorbing boundary condition and perfectly matched layer.
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A study of perfectly matched layers for joint multicomponent reverse-time migration 被引量:3
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作者 杜启振 秦童 +1 位作者 朱钇同 毕丽飞 《Applied Geophysics》 SCIE CSCD 2010年第2期166-173,194,195,共10页
Reverse-time migration in finite space requires effective boundary processing technology to eliminate the artificial truncation boundary effect in the migration result.On the basis of the elastic velocity-stress equat... Reverse-time migration in finite space requires effective boundary processing technology to eliminate the artificial truncation boundary effect in the migration result.On the basis of the elastic velocity-stress equations in vertical transversely isotropic media and the idea of the conventional split perfectly matched layer(PML),the PML wave equations in reverse-time migration are derived in this paper and then the high order staggered grid discrete schemes are subsequently given.Aiming at the"reflections"from the boundary to the computational domain,as well as the effect of seismic event's abrupt changes at the two ends of the seismic array,the PML arrangement in reverse-time migration is given.The synthetic and real elastic,prestack,multi-component,reverse-time depth migration results demonstrate that this method has much better absorbing effects than other methods and the joint migration produces good imaging results. 展开更多
关键词 perfectly matched layer(PML) absorbing boundary reverse-time migration velocity-stress equation MULTI-COMPONENT
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Perfectly Matched Layer for an Elastic Parabolic Equation Model in Ocean Acoustics 被引量:5
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作者 XU Chuanxiu ZHANG Haigang +3 位作者 PIAO Shengchun YANG Shi’e SUN Sipeng TANG Jun 《Journal of Ocean University of China》 SCIE CAS CSCD 2017年第1期57-64,共8页
The perfectly matched layer(PML) is an effective technique for truncating unbounded domains with minimal spurious reflections. A fluid parabolic equation(PE) model applying PML technique was previously used to analyze... The perfectly matched layer(PML) is an effective technique for truncating unbounded domains with minimal spurious reflections. A fluid parabolic equation(PE) model applying PML technique was previously used to analyze the sound propagation problem in a range-dependent waveguide(Lu and Zhu, 2007). However, Lu and Zhu only considered a standard fluid PE to demonstrate the capability of the PML and did not take improved one-way models into consideration. They applied a [1/1] Padé approximant to the parabolic equation. The higher-order PEs are more accurate than standard ones when a very large angle propagation is considered. As for range-dependent problems, the techniques to handle the vertical interface between adjacent regions are mainly energy conserving and single-scattering. In this paper, the PML technique is generalized to the higher order elastic PE, as is to the higher order fluid PE. The correction of energy conserving is used in range-dependent waveguides. Simulation is made in both acoustic cases and seismo-acoustic cases. Range-independent and range-dependent waveguides are both adopted to test the accuracy and efficiency of this method. The numerical results illustrate that a PML is much more effective than an artificial absorbing layer(ABL) both in acoustic and seismo-acoustic sound propagation modeling. 展开更多
关键词 ELASTIC PARABOLIC EQUATION perfectly matched LAYER artificial absorbing LAYER
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An improved convolution perfectly matched layer for elastic second-order wave equation 被引量:2
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作者 Yang Ling-Yun Wu Guo-Chen +1 位作者 Li Qing-Yang Liang Zhan-Yuan 《Applied Geophysics》 SCIE CSCD 2021年第3期317-330,432,共15页
A convolution perfectly matched layer(CPML)can efficiently absorb boundary reflection in numerical simulation.However,the CPML is suitable for the first-order elastic wave equation and is difficult to apply directly t... A convolution perfectly matched layer(CPML)can efficiently absorb boundary reflection in numerical simulation.However,the CPML is suitable for the first-order elastic wave equation and is difficult to apply directly to the second-order elastic wave equation.In view of this,based on the first-order CPML absorbing boundary condition,we propose a new CPML(NCPML)boundary which can be directly applied to the second-order wave equation.We first systematically extend the first-order CPML technique into second-order wave equations,neglecting the space-varying characteristics of the partial damping coefficient in the complex-frequency domain,avoiding the generation of convolution in the time domain.We then transform the technique back to the time domain through the inverse Fourier transform.Numerical simulation indicates that the space-varying characteristics of the attenuation factor have little influence on the absorption effect and increase the memory at the same time.A number of numerical examples show that the NCPML proposed in this study is effective in simulating elastic wave propagation,and this algorithm is more efficient and requires less memory allocation than the conventional PML absorbing boundary. 展开更多
关键词 Convolutional perfectly matched layer absorbing boundary conditions second-order elastic wave equation numerical simulation
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APPLICATION OF THE PML ABSORBING BOUNDARY CONDITION TO FD-TD SIMULATION
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作者 Guo Ziqin Lin Deyun(Dept. of Electronic Engineering, Tsinghua University, Beijing 100084) 《Journal of Electronics(China)》 1998年第2期168-173,共6页
The key problem of finite-difference time-domain (FD-TD) method is the skillful application of special conditions on the boundaries of the computational domain. A new technique named Perfectly Matched Layer(PML) yield... The key problem of finite-difference time-domain (FD-TD) method is the skillful application of special conditions on the boundaries of the computational domain. A new technique named Perfectly Matched Layer(PML) yields a robust Absorbing Boundary Condition(ABC) independent of the angle of incidence and the frequency of outgoing waves. In this paper, the principle of the PML technique is briefly presented. Then some problems in the application and their settlements are discussed emphatically. Finally three numerical tests and a measured result are devoted to examine the accuracy and effectiveness of this approach. 展开更多
关键词 FINITE-DIFFERENCE TIME-DOMAIN absorbing BOUNDARY CONDITION perfectly matched layer REFLECTION COEFFICIENT
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基于金属-介质-金属的可调谐窄带完美吸收的研究
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作者 王晓坤 李周 梁国龙 《中国光学(中英文)》 EI CAS CSCD 北大核心 2024年第2期263-270,共8页
为了实现窄带完美吸收,本文提出了一种简单的三层金-二氧化硅-金薄膜(MDM)结构。通过电磁波时域差分算法(FDTD)进行模拟仿真和理论计算,详细分析了该结构的可调谐吸收特性,同时建立了理论模型,分析了其中存在的电磁模式以及窄带完美吸... 为了实现窄带完美吸收,本文提出了一种简单的三层金-二氧化硅-金薄膜(MDM)结构。通过电磁波时域差分算法(FDTD)进行模拟仿真和理论计算,详细分析了该结构的可调谐吸收特性,同时建立了理论模型,分析了其中存在的电磁模式以及窄带完美吸收的物理机制。首先,利用电磁波时域差分算法和传输矩阵算法(TMM)对该结构进行了理论计算,详细地分析了各个结构参数对吸收光谱的影响。然后,对该结构形成的窄带完美吸收物理机制进行了分析讨论。最后,利用磁控溅射制备手段,成功制备了三层结构的样片。实验观测到的结果与理论仿真一致。实验结果表明:本文提出的窄带完美吸收结构,最窄带宽约为21 nm,最高吸收可达99.51%,基本实现了窄带完美吸收。本文研究成果为相关应用奠定了基础。 展开更多
关键词 薄膜 完美吸收 超薄薄膜
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等离激元银金属膜耦合氮化硅纳米空腔在可见光-近红外区间的多谱带完美吸收和传感性质的仿真研究 被引量:1
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作者 王家正 刘佳 +3 位作者 孙维鑫 周剑章 吴德印 田中群 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2024年第3期663-669,共7页
具有多谱带完美吸收效应的超构材料在光学滤波和折射率传感等多种应用中是理想的材料。提出了一种由银金属上的氮化硅介电纳米空腔阵列组成的多谱带窄带完美吸收超构材料。有限元仿真给出了四个最高可达99.9%的吸收峰,以及最小达到0.74... 具有多谱带完美吸收效应的超构材料在光学滤波和折射率传感等多种应用中是理想的材料。提出了一种由银金属上的氮化硅介电纳米空腔阵列组成的多谱带窄带完美吸收超构材料。有限元仿真给出了四个最高可达99.9%的吸收峰,以及最小达到0.74 nm的吸收峰宽。这些吸收谱带来自于表面晶格模式和三个表面等离激元极化子模式。此外,这些模式的谱峰对超构材料几何外形和环境介质光学参数的变化敏感,从而在可见光-近红外范围内可以被调控。用于折射率传感时,其具有347 nm每折射率单位的灵敏度,Figure of Merit达到469。这些特性令这一材料适用于光学滤波器和折射率传感器等用途。 展开更多
关键词 完美吸收超构材料 结构敏感吸收谱 折射率传感器 表面等离激元
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Visible-near infrared ultra-broadband polarization-independent metamaterial perfect absorber involving phase-change materials 被引量:6
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作者 Ximin Tian Zhi-Yuan Li 《Photonics Research》 SCIE EI 2016年第4期146-152,共7页
We numerically demonstrate a novel ultra-broadband polarization-independent metamaterial perfect absorber in the visible and near-infrared region involving the phase-change material Ge_2Sb_2Te_5(GST).The novel perfect... We numerically demonstrate a novel ultra-broadband polarization-independent metamaterial perfect absorber in the visible and near-infrared region involving the phase-change material Ge_2Sb_2Te_5(GST).The novel perfect absorber scheme consists of an array of high-index strong-absorbance GST square resonators separated from a continuous Au substrate by a low-index lossless dielectric layer(silica)and a high-index GST planar cavity.Three absorption peaks with the maximal absorbance up to 99.94% are achieved,owing to the excitation of plasmon-like dipolar or quadrupole resonances from the high-index GST resonators and cavity resonances generated by the GST planar cavity.The intensities and positions of the absorption peaks show strong dependence on structural parameters.A heat transfer model is used to investigate the temporal variation of temperature within the GST region.The results show that the temperature of amorphous GST can reach up to 433 K of the phase transition temperature from room temperature in just 0.37 ns with a relatively low incident light intensity of 1.11×10~8W∕m^2,due to the enhanced ultra-broadband light absorbance through strong plasmon resonances and cavity resonance in the absorber.The study suggests a feasible means to lower the power requirements for photonic devices based on a thermal phase change via engineering ultra-broadband light absorbers. 展开更多
关键词 MMPA Visible-near infrared ultra-broadband polarization-independent metamaterial perfect absorber involving phase-change materials GST
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Tunable and multichannel terahertz perfect absorber due to Tamm surface plasmons with graphene 被引量:9
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作者 XI WANG XING JIANG +3 位作者 QI YOU JUN GUO XIAOYU DAI YUANJIANG XIANG 《Photonics Research》 SCIE EI 2017年第6期61-67,共7页
In this paper, we have shown that perfect absorption at terahertz frequencies can be achieved by using a composite structure where graphene is coated on one-dimensional photonic crystal(1 DPC) separated by a dielectri... In this paper, we have shown that perfect absorption at terahertz frequencies can be achieved by using a composite structure where graphene is coated on one-dimensional photonic crystal(1 DPC) separated by a dielectric. Due to the excitation of optical Tamm states(OTSs) at the interface between the graphene and 1 DPC, a strong absorption phenomenon occurs induced by the coupling of the incident light and OTSs. Although the perfect absorption produced by a metal–distributed Bragg reflector structure has been researched extensively, it is generally at a fixed frequency and not tunable. Here, we show that the perfect absorption at terahertz frequency not only can be tuned to different frequencies but also exhibits a high absorption over a wide angle range. In addition,the absorption of the proposed structure is insensitive to the polarization, and multichannel absorption can berealized by controlling the thickness of the top layer. 展开更多
关键词 Tunable and multichannel terahertz perfect absorber due to Tamm surface plasmons with graphene DBR THz
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Tuning the metal filling fraction in metal-insulator-metal ultra-broadband perfect absorbers to maximize the absorption bandwidth 被引量:4
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作者 AMIR GHOBADI HODJAT HAJIAN +2 位作者 ALIREZA RAHIMI RASHED BAYRAM BUTUN EKMEL OZBAY 《Photonics Research》 SCIE EI 2018年第3期168-176,共9页
In this paper, we propose a methodology to maximize the absorption bandwidth of a metal-insulator-metal(MIM) based absorber. The proposed structure is made of a Cr-Al_2O_3-Cr multilayer design. At the initial step,the... In this paper, we propose a methodology to maximize the absorption bandwidth of a metal-insulator-metal(MIM) based absorber. The proposed structure is made of a Cr-Al_2O_3-Cr multilayer design. At the initial step,the optimum MIM planar design is fabricated and optically characterized. The results show absorption above 0.9 from 400 nm to 850 nm. Afterward, the transfer matrix method is used to find the optimal condition for the perfect light absorption in an ultra-broadband frequency range. This modeling approach predicts that changing the filling fraction of the top Cr layer can extend light absorption toward longer wavelengths. We experimentally proved that the use of proper top Cr thickness and annealing temperature leads to a nearly perfect light absorption from 400 nm to 1150 nm, which is much broader than that of a planar design. Therefore, while keeping the overall process lithography-free, the absorption functionality of the design can be significantly improved. The results presented here can serve as a beacon for future performance-enhanced multilayer designs where a simple fabrication step can boost the overall device response without changing its overall thickness and fabrication simplicity. 展开更多
关键词 Tuning the metal filling fraction perfect absorbers maximize the absorption bandwidth MIM
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