In this work, some solutions such as Mori-Tanaka approximation (MTA), Differential approximations (DA), and Fast Fourier transformation method (FFT) were applied to estimate the elastic bulk and shear modulus of three-phase composites in 2D. In which two different sizes of circular inclusions are arranged randomly non-overlapping in a continuous matrix. The numerical solutions using FFT analysis were compared with DA, MTA, and Hashin-Strikman's bounds. The MTA and DA reasonably agreeable solution with the FFT solution shows the effectiveness of the approximation methods, which makes MTA, DA useful with simplicity and ease of application.
{"title":"FFT, DA, and Mori-Tanaka approximation to determine the elastic moduli of three-phase composites with the random inclusions","authors":"V. Nguyen","doi":"10.1051/epjam/2022007","DOIUrl":"https://doi.org/10.1051/epjam/2022007","url":null,"abstract":"In this work, some solutions such as Mori-Tanaka approximation (MTA), Differential approximations (DA), and Fast Fourier transformation method (FFT) were applied to estimate the elastic bulk and shear modulus of three-phase composites in 2D. In which two different sizes of circular inclusions are arranged randomly non-overlapping in a continuous matrix. The numerical solutions using FFT analysis were compared with DA, MTA, and Hashin-Strikman's bounds. The MTA and DA reasonably agreeable solution with the FFT solution shows the effectiveness of the approximation methods, which makes MTA, DA useful with simplicity and ease of application.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"65 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Heavily doped semiconductors have emerged as low-loss and tunable materials for plasmonics at mid-infrared frequencies. We analyze the nonlinear optical response of free electrons and show how nonlinear optical phenomena associated with high electron concentration are influenced by the intrinsic properties of semiconductors, namely background permittivity and effective mass. We apply our recently developed hydrodynamic description that takes into account nonlinear contributions up to the third order, usually negligible for noble metals, to compare third-harmonic generation from InP, Ge, GaAs, Si, ITO and InSb. We show how free electron nonlinearities may be enhanced with a proper choice of the semiconductor.
{"title":"Free electron harmonic generation in heavily doped semiconductors: the role of the materials properties","authors":"F. De Luca, Michele Ortolani, C. Ciracì","doi":"10.1051/epjam/2022011","DOIUrl":"https://doi.org/10.1051/epjam/2022011","url":null,"abstract":"Heavily doped semiconductors have emerged as low-loss and tunable materials for plasmonics at mid-infrared frequencies. We analyze the nonlinear optical response of free electrons and show how nonlinear optical phenomena associated with high electron concentration are influenced by the intrinsic properties of semiconductors, namely background permittivity and effective mass. We apply our recently developed hydrodynamic description that takes into account nonlinear contributions up to the third order, usually negligible for noble metals, to compare third-harmonic generation from InP, Ge, GaAs, Si, ITO and InSb. We show how free electron nonlinearities may be enhanced with a proper choice of the semiconductor.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saeid Izadshenas, P. Masłowski, T. Herr, K. Słowik
A metasurface in the metal-insulator-grating configuration is designed and optimised to support enhancement of coherent Raman signal of selected molecules orders of magnitude above the single-molecule detection threshold. The tunability is demonstrated by adjusting the structure to match selected Raman peaks of rhodamine, however, its spectral response is broad enough to cover a range of Raman shifts. Finally, the grating allows switching between distinct values of Raman shift with a single metasurface illuminated at different angles.
{"title":"Multiresonant metasurface for Raman spectroscopy beyond single molecule detection level","authors":"Saeid Izadshenas, P. Masłowski, T. Herr, K. Słowik","doi":"10.1051/epjam/2022009","DOIUrl":"https://doi.org/10.1051/epjam/2022009","url":null,"abstract":"A metasurface in the metal-insulator-grating configuration is designed and optimised to support enhancement of coherent Raman signal of selected molecules orders of magnitude above the single-molecule detection threshold. The tunability is demonstrated by adjusting the structure to match selected Raman peaks of rhodamine, however, its spectral response is broad enough to cover a range of Raman shifts. Finally, the grating allows switching between distinct values of Raman shift with a single metasurface illuminated at different angles.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Topological states are useful because they are robust against disorder and imperfection. In this study, we consider the effect of disorder and the breaking of parity symmetry on a topological network system in which the edge states are protected by Chern numbers. In the absence of periodicity, the local Chern number is adopted to characterize the topological features of the network. Our numerical results show that the local Chern number and the edge states are very robust against onsite disorder as long as the gap of the bulk state continuum remains open and survives even when the bulk band gap is closed. Breaking the parity symmetry can destroy the quantization of local Chern numbers, compromising the existence of edge modes. We observed non-integer local Chern number peaks that are non-zero inside the bulk bands but these non-zero non-integral local Chern numbers are not associated with the existence of robust edge states.
{"title":"Disordered transmission-line networks with and without parity symmetry","authors":"Tianshu Jiang, C. T. Chan","doi":"10.1051/epjam/2022001","DOIUrl":"https://doi.org/10.1051/epjam/2022001","url":null,"abstract":"Topological states are useful because they are robust against disorder and imperfection. In this study, we consider the effect of disorder and the breaking of parity symmetry on a topological network system in which the edge states are protected by Chern numbers. In the absence of periodicity, the local Chern number is adopted to characterize the topological features of the network. Our numerical results show that the local Chern number and the edge states are very robust against onsite disorder as long as the gap of the bulk state continuum remains open and survives even when the bulk band gap is closed. Breaking the parity symmetry can destroy the quantization of local Chern numbers, compromising the existence of edge modes. We observed non-integer local Chern number peaks that are non-zero inside the bulk bands but these non-zero non-integral local Chern numbers are not associated with the existence of robust edge states.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2021-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43950842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The ellipse assemblage model with imperfect interface has quite complex microstructure, that can be considered an extension of the circle assemblage model with imperfect interfaces. The paper introduces an approximate method for computing the effective conductivity of isotropic composites with imperfect interfaces in two-dimensional space. Based on the coated-ellipse assemblage model and the equivalent inclusion approximation, one can determine the effective thermal conductivity of the composites. The polarization approximation is given in an explicit form (PEK) and this method will be applied to calculate the effective conductivity of the composite with Kapitza thermal resistance model. The PEK result will have compared with the Fast Fourier Transform (FFT) simulation and Hashin-strikman bounds (HS).
{"title":"Estimating the effective conductivity for ellipse-inclusion model with Kapitza thermal resistance","authors":"V. Nguyen","doi":"10.1051/epjam/2021010","DOIUrl":"https://doi.org/10.1051/epjam/2021010","url":null,"abstract":"The ellipse assemblage model with imperfect interface has quite complex microstructure, that can be considered an extension of the circle assemblage model with imperfect interfaces. The paper introduces an approximate method for computing the effective conductivity of isotropic composites with imperfect interfaces in two-dimensional space. Based on the coated-ellipse assemblage model and the equivalent inclusion approximation, one can determine the effective thermal conductivity of the composites. The polarization approximation is given in an explicit form (PEK) and this method will be applied to calculate the effective conductivity of the composite with Kapitza thermal resistance model. The PEK result will have compared with the Fast Fourier Transform (FFT) simulation and Hashin-strikman bounds (HS).","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823892","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xin Wang, Xianfeng Tang, Shifeng Li, J. Ling, Xuanming Zhang, Z. Duan
As a kind of artificially structured media, electromagnetic metamaterials (MTMs) have exotic electromagnetic properties that are not found or difficult to achieve in natural materials. This class of metal/dielectric-structured artificial media has attracted great attention during the past two decades and made important breakthroughs. A variety of passive and active devices based on MTMs have been developed rapidly. Especially MTM klystrons, which show very remarkable advantages, including miniaturization, high gain, and high efficiency in the microwave band. MTM extended interaction klystrons creatively combine the advantages of MTMs, extended interaction technology, and klystrons. It provides a new design idea for the development of brand-new klystrons with high performance. In this review paper, we report the recent advances in MTM klystrons including MTM extended interaction oscillator and MTM extended interaction klystron amplifier. Furthermore, the prospects and challenges of MTM klystrons are discussed. Finally, the development trend is concluded.
{"title":"Recent advances in metamaterial klystrons","authors":"Xin Wang, Xianfeng Tang, Shifeng Li, J. Ling, Xuanming Zhang, Z. Duan","doi":"10.1051/EPJAM/2021001","DOIUrl":"https://doi.org/10.1051/EPJAM/2021001","url":null,"abstract":"As a kind of artificially structured media, electromagnetic metamaterials (MTMs) have exotic electromagnetic properties that are not found or difficult to achieve in natural materials. This class of metal/dielectric-structured artificial media has attracted great attention during the past two decades and made important breakthroughs. A variety of passive and active devices based on MTMs have been developed rapidly. Especially MTM klystrons, which show very remarkable advantages, including miniaturization, high gain, and high efficiency in the microwave band. MTM extended interaction klystrons creatively combine the advantages of MTMs, extended interaction technology, and klystrons. It provides a new design idea for the development of brand-new klystrons with high performance. In this review paper, we report the recent advances in MTM klystrons including MTM extended interaction oscillator and MTM extended interaction klystron amplifier. Furthermore, the prospects and challenges of MTM klystrons are discussed. Finally, the development trend is concluded.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Vellucci, A. Monti, M. Barbuto, A. Toscano, F. Bilotti
Among the different cloaking applications proposed in the literature, the antenna framework has emerged as one of the most fruitful and mature field. In particular, mantle cloaking approach has proven to be a powerful tool for enabling unprecedented possibilities in antenna design. Here, we provide a review of the most significant works in the field of electromagnetic invisibility for antenna applications, demonstrating the versatility of cloaking metasurfaces in antenna scenarios. We also discuss our recent results and investigations on the design of advanced cloaking metasurfaces equipped with electronic components and circuits and able enriching the antenna intelligence.
{"title":"Progress and perspective on advanced cloaking metasurfaces: from invisibility to intelligent antennas","authors":"S. Vellucci, A. Monti, M. Barbuto, A. Toscano, F. Bilotti","doi":"10.1051/EPJAM/2020013","DOIUrl":"https://doi.org/10.1051/EPJAM/2020013","url":null,"abstract":"Among the different cloaking applications proposed in the literature, the antenna framework has emerged as one of the most fruitful and mature field. In particular, mantle cloaking approach has proven to be a powerful tool for enabling unprecedented possibilities in antenna design. Here, we provide a review of the most significant works in the field of electromagnetic invisibility for antenna applications, demonstrating the versatility of cloaking metasurfaces in antenna scenarios. We also discuss our recent results and investigations on the design of advanced cloaking metasurfaces equipped with electronic components and circuits and able enriching the antenna intelligence.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xinghua Li, Mingde Feng, Jiafu Wang, Xinmin Fu, Yajuan Han, S. Sui, Y. Pang, Qu Shaobo
The back-scattering from front edge diffraction contributes significantly to mono-static radar cross section under TE-polarization when the specular reflection of an object is eliminated by elaborate shaping. With the aim to suppress the back-scattering of thin metallic edge, we propose to achieve wideband radar cross section (RCS) reduction by integrating an absorbing structure (AS) in front of the edge. The unit cell of AS is composed of a longitudinal array of metallic strips with linearly decreasing lengths. Under TE-polarized illumination, spoof surface plasmon polariton (SSPP) can be excited with high efficiency. Due to the deep-subwavelength property of SSPP, electromagnetic waves are highly confined around the AS, leading to strong local field enhancement and hence to wideband absorption. In this way, back-scattering of the edge is suppressed and the mono-static RCS can be reduced significantly over wide band. To verify this method, we designed, fabricated and measured a prototype. The results of both simulation and measurement indicate that our proposal can significantly suppress edge scattering, whose RCS reduction more than 10 dB achieves at range of 8.8–17.8 GHz under TE polarization. This work provides a new alternative of suppressing edge diffraction and may find applications in electromagnetic compatibility, radar stealth, etc.
{"title":"Wideband RCS reduction of thin metallic edges mediated by spoof surface plasmon polaritons","authors":"Xinghua Li, Mingde Feng, Jiafu Wang, Xinmin Fu, Yajuan Han, S. Sui, Y. Pang, Qu Shaobo","doi":"10.1051/EPJAM/2020018","DOIUrl":"https://doi.org/10.1051/EPJAM/2020018","url":null,"abstract":"The back-scattering from front edge diffraction contributes significantly to mono-static radar cross section under TE-polarization when the specular reflection of an object is eliminated by elaborate shaping. With the aim to suppress the back-scattering of thin metallic edge, we propose to achieve wideband radar cross section (RCS) reduction by integrating an absorbing structure (AS) in front of the edge. The unit cell of AS is composed of a longitudinal array of metallic strips with linearly decreasing lengths. Under TE-polarized illumination, spoof surface plasmon polariton (SSPP) can be excited with high efficiency. Due to the deep-subwavelength property of SSPP, electromagnetic waves are highly confined around the AS, leading to strong local field enhancement and hence to wideband absorption. In this way, back-scattering of the edge is suppressed and the mono-static RCS can be reduced significantly over wide band. To verify this method, we designed, fabricated and measured a prototype. The results of both simulation and measurement indicate that our proposal can significantly suppress edge scattering, whose RCS reduction more than 10 dB achieves at range of 8.8–17.8 GHz under TE polarization. This work provides a new alternative of suppressing edge diffraction and may find applications in electromagnetic compatibility, radar stealth, etc.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Miniaci, N. Kherraz, C. Croënne, M. Mazzotti, M. Morvaridi, A. Gliozzi, M. Onorato, F. Bosia, N. Pugno
Large scale elastic metamaterials have recently attracted increasing interest in the scientific community for their potential as passive isolation structures for seismic waves. In particular, so-called “seismic shields” have been proposed for the protection of large areas where other isolation strategies (e.g. dampers) are not workable solutions. In this work, we investigate the feasibility of an innovative design based on hierarchical design of the unit cell, i.e. a structure with a self-similar geometry repeated at different scales. Results show how the introduction of hierarchy allows the conception of unit cells exhibiting reduced size with respect to the wavelength while maintaining the same or improved isolation efficiency at frequencies of interest for earthquake engineering. This allows to move closer to the practical realization of such seismic shields, where low-frequency operation and acceptable size are both essential characteristics for feasibility.
{"title":"Hierarchical large-scale elastic metamaterials for passive seismic wave mitigation","authors":"M. Miniaci, N. Kherraz, C. Croënne, M. Mazzotti, M. Morvaridi, A. Gliozzi, M. Onorato, F. Bosia, N. Pugno","doi":"10.1051/EPJAM/2021009","DOIUrl":"https://doi.org/10.1051/EPJAM/2021009","url":null,"abstract":"Large scale elastic metamaterials have recently attracted increasing interest in the scientific community for their potential as passive isolation structures for seismic waves. In particular, so-called “seismic shields” have been proposed for the protection of large areas where other isolation strategies (e.g. dampers) are not workable solutions. In this work, we investigate the feasibility of an innovative design based on hierarchical design of the unit cell, i.e. a structure with a self-similar geometry repeated at different scales. Results show how the introduction of hierarchy allows the conception of unit cells exhibiting reduced size with respect to the wavelength while maintaining the same or improved isolation efficiency at frequencies of interest for earthquake engineering. This allows to move closer to the practical realization of such seismic shields, where low-frequency operation and acceptable size are both essential characteristics for feasibility.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yanjie Wu, J. Xiong, Feng Deng, Hail Lin, Youyi Wang
A miniaturized frequency selective rasorber (FSR) with high selectivity passband and wideband absorption properties is presented. Its performance as an absorber over a wide absorption band from 8.08 to 18.08 GHz through the structure of metal incurved square loop structure loaded resistors. The frequency selective surface (FSS) using Jerusalem cross array and metallic patch realizes the transmission frequency band from 2.7 to 3.52 GHz. And the insertion loss (IL) is 0.37 dB at 3.08 GHz. The symmetry and miniaturized elements design enable the proposed FSR to achieve satisfactory incident angle stability. Its small unit size effectively avoids the generation of grating lobes in the absorption band and the interference to Radar Cross Section (RCS) reduction.
{"title":"A miniaturized frequency selective rasorber with high selectivity passband and wideband absorption properties","authors":"Yanjie Wu, J. Xiong, Feng Deng, Hail Lin, Youyi Wang","doi":"10.1051/EPJAM/2020017","DOIUrl":"https://doi.org/10.1051/EPJAM/2020017","url":null,"abstract":"A miniaturized frequency selective rasorber (FSR) with high selectivity passband and wideband absorption properties is presented. Its performance as an absorber over a wide absorption band from 8.08 to 18.08 GHz through the structure of metal incurved square loop structure loaded resistors. The frequency selective surface (FSS) using Jerusalem cross array and metallic patch realizes the transmission frequency band from 2.7 to 3.52 GHz. And the insertion loss (IL) is 0.37 dB at 3.08 GHz. The symmetry and miniaturized elements design enable the proposed FSR to achieve satisfactory incident angle stability. Its small unit size effectively avoids the generation of grating lobes in the absorption band and the interference to Radar Cross Section (RCS) reduction.","PeriodicalId":43689,"journal":{"name":"EPJ Applied Metamaterials","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57823294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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