The Experts below are selected from a list of 213 Experts worldwide ranked by ideXlab platform

Jacob Schalch - One of the best experts on this subject based on the ideXlab platform.

  • a survey of theoretical models for terahertz electromagnetic metamaterial absorbers
    Sensors and Actuators A-physical, 2019
    Co-Authors: Guangwu Dua, Jacob Schalch, Xiaoguang Zhao, Chunxu Che, R D Averi, Xi Zhang
    Abstract:

    Abstract In the past few decades, electromagnetic metamaterial absorbers have attracted tremendous attention due to near unity absorption of incident electromagnetic waves over a desired frequency range determined by the metamaterial inclusions as opposed to the constituent material properties. Importantly, metamaterial absorbers enable numerous potential applications which include wave manipulation, terahertz and infrared imaging, energy harvesting, radiative cooling, and chemical detection. To understand the underlying physics of metamaterial absorbers, various theoretical models have been developed. However, these models are seemingly conceptually unrelated, each yielding a distinct set of equations and conclusions. This paper reviews four prevalent theoretical approaches which include effective medium Theory, transmission line modelling, coupled mode Theory, and Interference Theory. We show that each of the four theoretical approaches provides an understanding of metamaterial absorbers from different points-of-view, each with distinct advantages and limitations. Moreover, the four theoretical models are interconnected and we discuss that, quite generally, impedance matching is the crucial condition for perfect absorption.

  • terahertz metamaterial perfect absorber with continuously tunable air spacer layer
    Applied Physics Letters, 2018
    Co-Authors: Jacob Schalch, Guangwu Duan, Xiaoguang Zhao, Xin Zhang, R D Averitt
    Abstract:

    We present a comprehensive investigation of a continuously tunable metamaterial perfect absorber operating at terahertz frequencies. In particular, we investigate a three-layer absorber structure consisting of a layer of split ring resonators and a metallic ground plane, with a central layer consisting of a mechanically tunable air-spaced layer. The absorber was characterized using terahertz time-domain spectroscopy in reflection (at normal incidence) as a function of spacer thickness from 0 to 1000 μm. Our experimental measurements reveal the detailed evolution of the absorption bands as a function of spacing, in excellent agreement with analysis using Interference Theory and simulation. Our Fabry-Perot-like structure provides an avenue for achieving massive tunability in metamaterial absorber devices.We present a comprehensive investigation of a continuously tunable metamaterial perfect absorber operating at terahertz frequencies. In particular, we investigate a three-layer absorber structure consisting of a layer of split ring resonators and a metallic ground plane, with a central layer consisting of a mechanically tunable air-spaced layer. The absorber was characterized using terahertz time-domain spectroscopy in reflection (at normal incidence) as a function of spacer thickness from 0 to 1000 μm. Our experimental measurements reveal the detailed evolution of the absorption bands as a function of spacing, in excellent agreement with analysis using Interference Theory and simulation. Our Fabry-Perot-like structure provides an avenue for achieving massive tunability in metamaterial absorber devices.

  • analysis of the thickness dependence of metamaterial absorbers at terahertz frequencies
    Optics Express, 2018
    Co-Authors: Guangwu Duan, Jacob Schalch, Xiaoguang Zhao, R D Averitt, Jingdi Zhang, Xin Zhang
    Abstract:

    Metamaterial absorbers typically consist of a metamaterial layer, a dielectric spacer layer, and a metallic ground plane. We have investigated the dependence of the metamaterial absorption maxima on the spacer layer thickness and the reflection coefficient of the metamaterial layer obtained in the absence of the ground plane layer. Specifically, we employ Interference Theory to obtain an analytical expression for the spacer thickness needed to maximize the absorption at a given frequency. The efficacy of this simple expression is experimentally verified at terahertz frequencies through detailed measurements of the absorption spectra of a series of metamaterials structures with different spacer thicknesses. Using an array of split-ring resonators (SRRs) as the metamaterial layer and SU8 as the spacer material we observe that the absorption peaks redshift as the spacer thickness is increased, in excellent agreement with our analysis. Our findings can be applied to guide metamaterial absorber designs and understand the absorption peak frequency shift of sensors based on metamaterial absorbers.

R D Averitt - One of the best experts on this subject based on the ideXlab platform.

  • terahertz metamaterial perfect absorber with continuously tunable air spacer layer
    Applied Physics Letters, 2018
    Co-Authors: Jacob Schalch, Guangwu Duan, Xiaoguang Zhao, Xin Zhang, R D Averitt
    Abstract:

    We present a comprehensive investigation of a continuously tunable metamaterial perfect absorber operating at terahertz frequencies. In particular, we investigate a three-layer absorber structure consisting of a layer of split ring resonators and a metallic ground plane, with a central layer consisting of a mechanically tunable air-spaced layer. The absorber was characterized using terahertz time-domain spectroscopy in reflection (at normal incidence) as a function of spacer thickness from 0 to 1000 μm. Our experimental measurements reveal the detailed evolution of the absorption bands as a function of spacing, in excellent agreement with analysis using Interference Theory and simulation. Our Fabry-Perot-like structure provides an avenue for achieving massive tunability in metamaterial absorber devices.We present a comprehensive investigation of a continuously tunable metamaterial perfect absorber operating at terahertz frequencies. In particular, we investigate a three-layer absorber structure consisting of a layer of split ring resonators and a metallic ground plane, with a central layer consisting of a mechanically tunable air-spaced layer. The absorber was characterized using terahertz time-domain spectroscopy in reflection (at normal incidence) as a function of spacer thickness from 0 to 1000 μm. Our experimental measurements reveal the detailed evolution of the absorption bands as a function of spacing, in excellent agreement with analysis using Interference Theory and simulation. Our Fabry-Perot-like structure provides an avenue for achieving massive tunability in metamaterial absorber devices.

  • analysis of the thickness dependence of metamaterial absorbers at terahertz frequencies
    Optics Express, 2018
    Co-Authors: Guangwu Duan, Jacob Schalch, Xiaoguang Zhao, R D Averitt, Jingdi Zhang, Xin Zhang
    Abstract:

    Metamaterial absorbers typically consist of a metamaterial layer, a dielectric spacer layer, and a metallic ground plane. We have investigated the dependence of the metamaterial absorption maxima on the spacer layer thickness and the reflection coefficient of the metamaterial layer obtained in the absence of the ground plane layer. Specifically, we employ Interference Theory to obtain an analytical expression for the spacer thickness needed to maximize the absorption at a given frequency. The efficacy of this simple expression is experimentally verified at terahertz frequencies through detailed measurements of the absorption spectra of a series of metamaterials structures with different spacer thicknesses. Using an array of split-ring resonators (SRRs) as the metamaterial layer and SU8 as the spacer material we observe that the absorption peaks redshift as the spacer thickness is increased, in excellent agreement with our analysis. Our findings can be applied to guide metamaterial absorber designs and understand the absorption peak frequency shift of sensors based on metamaterial absorbers.

Xiaoguang Zhao - One of the best experts on this subject based on the ideXlab platform.

  • a survey of theoretical models for terahertz electromagnetic metamaterial absorbers
    Sensors and Actuators A-physical, 2019
    Co-Authors: Guangwu Dua, Jacob Schalch, Xiaoguang Zhao, Chunxu Che, R D Averi, Xi Zhang
    Abstract:

    Abstract In the past few decades, electromagnetic metamaterial absorbers have attracted tremendous attention due to near unity absorption of incident electromagnetic waves over a desired frequency range determined by the metamaterial inclusions as opposed to the constituent material properties. Importantly, metamaterial absorbers enable numerous potential applications which include wave manipulation, terahertz and infrared imaging, energy harvesting, radiative cooling, and chemical detection. To understand the underlying physics of metamaterial absorbers, various theoretical models have been developed. However, these models are seemingly conceptually unrelated, each yielding a distinct set of equations and conclusions. This paper reviews four prevalent theoretical approaches which include effective medium Theory, transmission line modelling, coupled mode Theory, and Interference Theory. We show that each of the four theoretical approaches provides an understanding of metamaterial absorbers from different points-of-view, each with distinct advantages and limitations. Moreover, the four theoretical models are interconnected and we discuss that, quite generally, impedance matching is the crucial condition for perfect absorption.

  • terahertz metamaterial perfect absorber with continuously tunable air spacer layer
    Applied Physics Letters, 2018
    Co-Authors: Jacob Schalch, Guangwu Duan, Xiaoguang Zhao, Xin Zhang, R D Averitt
    Abstract:

    We present a comprehensive investigation of a continuously tunable metamaterial perfect absorber operating at terahertz frequencies. In particular, we investigate a three-layer absorber structure consisting of a layer of split ring resonators and a metallic ground plane, with a central layer consisting of a mechanically tunable air-spaced layer. The absorber was characterized using terahertz time-domain spectroscopy in reflection (at normal incidence) as a function of spacer thickness from 0 to 1000 μm. Our experimental measurements reveal the detailed evolution of the absorption bands as a function of spacing, in excellent agreement with analysis using Interference Theory and simulation. Our Fabry-Perot-like structure provides an avenue for achieving massive tunability in metamaterial absorber devices.We present a comprehensive investigation of a continuously tunable metamaterial perfect absorber operating at terahertz frequencies. In particular, we investigate a three-layer absorber structure consisting of a layer of split ring resonators and a metallic ground plane, with a central layer consisting of a mechanically tunable air-spaced layer. The absorber was characterized using terahertz time-domain spectroscopy in reflection (at normal incidence) as a function of spacer thickness from 0 to 1000 μm. Our experimental measurements reveal the detailed evolution of the absorption bands as a function of spacing, in excellent agreement with analysis using Interference Theory and simulation. Our Fabry-Perot-like structure provides an avenue for achieving massive tunability in metamaterial absorber devices.

  • analysis of the thickness dependence of metamaterial absorbers at terahertz frequencies
    Optics Express, 2018
    Co-Authors: Guangwu Duan, Jacob Schalch, Xiaoguang Zhao, R D Averitt, Jingdi Zhang, Xin Zhang
    Abstract:

    Metamaterial absorbers typically consist of a metamaterial layer, a dielectric spacer layer, and a metallic ground plane. We have investigated the dependence of the metamaterial absorption maxima on the spacer layer thickness and the reflection coefficient of the metamaterial layer obtained in the absence of the ground plane layer. Specifically, we employ Interference Theory to obtain an analytical expression for the spacer thickness needed to maximize the absorption at a given frequency. The efficacy of this simple expression is experimentally verified at terahertz frequencies through detailed measurements of the absorption spectra of a series of metamaterials structures with different spacer thicknesses. Using an array of split-ring resonators (SRRs) as the metamaterial layer and SU8 as the spacer material we observe that the absorption peaks redshift as the spacer thickness is increased, in excellent agreement with our analysis. Our findings can be applied to guide metamaterial absorber designs and understand the absorption peak frequency shift of sensors based on metamaterial absorbers.

Xin Zhang - One of the best experts on this subject based on the ideXlab platform.

  • terahertz metamaterial perfect absorber with continuously tunable air spacer layer
    Applied Physics Letters, 2018
    Co-Authors: Jacob Schalch, Guangwu Duan, Xiaoguang Zhao, Xin Zhang, R D Averitt
    Abstract:

    We present a comprehensive investigation of a continuously tunable metamaterial perfect absorber operating at terahertz frequencies. In particular, we investigate a three-layer absorber structure consisting of a layer of split ring resonators and a metallic ground plane, with a central layer consisting of a mechanically tunable air-spaced layer. The absorber was characterized using terahertz time-domain spectroscopy in reflection (at normal incidence) as a function of spacer thickness from 0 to 1000 μm. Our experimental measurements reveal the detailed evolution of the absorption bands as a function of spacing, in excellent agreement with analysis using Interference Theory and simulation. Our Fabry-Perot-like structure provides an avenue for achieving massive tunability in metamaterial absorber devices.We present a comprehensive investigation of a continuously tunable metamaterial perfect absorber operating at terahertz frequencies. In particular, we investigate a three-layer absorber structure consisting of a layer of split ring resonators and a metallic ground plane, with a central layer consisting of a mechanically tunable air-spaced layer. The absorber was characterized using terahertz time-domain spectroscopy in reflection (at normal incidence) as a function of spacer thickness from 0 to 1000 μm. Our experimental measurements reveal the detailed evolution of the absorption bands as a function of spacing, in excellent agreement with analysis using Interference Theory and simulation. Our Fabry-Perot-like structure provides an avenue for achieving massive tunability in metamaterial absorber devices.

  • analysis of the thickness dependence of metamaterial absorbers at terahertz frequencies
    Optics Express, 2018
    Co-Authors: Guangwu Duan, Jacob Schalch, Xiaoguang Zhao, R D Averitt, Jingdi Zhang, Xin Zhang
    Abstract:

    Metamaterial absorbers typically consist of a metamaterial layer, a dielectric spacer layer, and a metallic ground plane. We have investigated the dependence of the metamaterial absorption maxima on the spacer layer thickness and the reflection coefficient of the metamaterial layer obtained in the absence of the ground plane layer. Specifically, we employ Interference Theory to obtain an analytical expression for the spacer thickness needed to maximize the absorption at a given frequency. The efficacy of this simple expression is experimentally verified at terahertz frequencies through detailed measurements of the absorption spectra of a series of metamaterials structures with different spacer thicknesses. Using an array of split-ring resonators (SRRs) as the metamaterial layer and SU8 as the spacer material we observe that the absorption peaks redshift as the spacer thickness is increased, in excellent agreement with our analysis. Our findings can be applied to guide metamaterial absorber designs and understand the absorption peak frequency shift of sensors based on metamaterial absorbers.

Minghai Liu - One of the best experts on this subject based on the ideXlab platform.

  • a triple band polarization and incident angle independent microwave metamaterial absorber with Interference Theory
    European Physical Journal B, 2016
    Co-Authors: Junfeng Chen, Shengming Wang, Xiutao Huang, Minghai Liu
    Abstract:

    We present the design, fabrication and characterization of an ultrathin triple-band metamaterial absorber (MMA) in the microwave frequencies. The unit cell of the MMA consists of three different sizes of electric split ring resonators (eSRRs) and continuous metal film separated by only 1 mm dielectric substrate. The single-band MMA of this structure is firstly investigated. Then, by tuning the scale factor of the unit cells, the proposed triple-band MMA achieves absorption peaks at 9.85 GHz, 13.05 GHz and 14.93 GHz, respectively. Electric field distributions at three resonant frequencies are investigated to qualitatively analyze the loss mechanism. The further simulated and experimental results indicate that the proposed MMA is also polarization- and incident angle-independent. Finally, the Interference Theory is introduced to quantitatively analyze the MMA, which provides good insight into the physics behind the absorbing structure. To calculate the absorption rates accurately, we employ a simulation strategy make the near-field coupling between two metallic layers get back (compensation method). The measured absorption spectra show an excellent agreement with the theoretical calculation and simulation results. Therefore, the explanation to the physical mechanism of the triple-band MMA is presented and verified.

  • high impedance surface based broadband absorbers with Interference Theory
    IEEE Transactions on Antennas and Propagation, 2015
    Co-Authors: Junfeng Chen, Shengming Wang, Xiutao Huang, Guodong Wang, Minghai Liu
    Abstract:

    A broadband and polarization-insensitive high-impedance surface (HIS) metamaterial absorber (MA) based on octagonal ring-shaped resistive patches is presented. The absorber is investigated theoretically, experimentally, and by simulation. The simulated results indicate that this structure obtains 10.28 GHz wide absorption from 3.65 to 13.93 GHz with absorptivity larger than 90% at the normal incidence. Experimental results are in accordance with those of the simulation results. The electromagnetic (EM) field distributions and the plots of surface power loss density have been illustrated to analyze the absorption mechanism of the structure. Further simulations of the absorptivity of the proposed absorber with different surface resistances and substrate thicknesses indicate that there exist optimal values for the design. The polarization-insensitive feature and the properties under oblique incidence are also investigated. Finally, the Interference Theory is introduced to analyze and interpret the broadband absorption mechanism at both normal and oblique incidences. The calculated absorption rates of the proposed absorber coincide well with the simulated results. Therefore, the simulated and experimental results verify the validity of the theoretically analytical method for this type of broadband absorber.