Full controlling of Fano resonances in metal-slit superlattice

Deng, Zi‐Lan; Yogesh, N.; Chen, Xiao; Chen, Wenjie; Dong, Jian‐Wen; Ouyang, Zhengbiao; Wang, Guo Ping

doi:10.1038/srep18461

Cited by 32 publications

(15 citation statements)

References 59 publications

(73 reference statements)

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“…We assume the width of this grating is infinite in y direction and only focus on the SSP mode in the x-z plane. The dispersion equation |M | = 0 is derived based on the mode matching method with perfect electric conductor boundary conditions [25], [26]. The matrix M is depicted in (1) (see appendix A).…”

Section: Model Presentationmentioning

confidence: 99%

Free-Electron-Driven Multi-Frequency Terahertz Radiation on a Super-Grating Structure

Zhu

et al. 2019

IEEE Access

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A free-electron-driven multi-frequency terahertz (THz) radiation based on a super-grating structure is elucidated in this paper. The super-grating, i.e., periodically depth-modulated metallic grating, has a peculiar dispersion characteristic, similar to the energy bands in a crystal due to the Brillouin zone folding effect. The multi-frequency radiation is stimulated in several directions with the excitation of a free electron as the synchronization points are in the radiative region. The radiation frequency can be independently tuned by the groove depths of the super-grating. The number of frequencies is tailored by the modulated period. Additionally, the multi-frequency THz radiation exhibits a frequency-locked effect during the energy variation of the free electron. Moreover, the radiation field intensity shows a significant enhancement compared with that of a conventional Smith-Purcell radiation. The work is promising for developing efficient on-chip THz radiation sources and boosts advanced THz applications such as communications, multi-frequency imaging, and beam diagnostics, etc.

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Section: Model Presentationmentioning

confidence: 99%

Free-Electron-Driven Multi-Frequency Terahertz Radiation on a Super-Grating Structure

Zhu

et al. 2019

IEEE Access

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“…In addition to the abovementioned problem related to the resonant nature of the Fano resonance, studies for controlling the resonance characteristics are also an important issue since it provides large tunability and flexibility for a variety of practical applications, such as optical sensor, elector‐optic modulator, and ultrasensitive spectroscopy . Most previous studies have controlled the line width, spectral position, and depth of the Fano resonances and demonstrated their multiple modes based on a passive method of geometric parameter sweep, which have very limited tuning range . There are some schemes using phase change materials/graphene, electromechanical control, and photo‐excited method .…”

Section: Introductionmentioning

confidence: 99%

Enhancement and Switching of Fano Resonance in Metamaterial

Mun

Yun

Choi

et al. 2018

Advanced Optical Materials

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of resonant scattering phenomenon that makes asymmetric line shape originating from destructive interference between broadband scattering within a continuum state (bright superradiant mode) and an excitation of discrete state (dark subradiant mode) similar to coupled oscillator system. It was firstly observed in scattering phenomenon of electrons from helium atom by Ugo Fano. [2] Since then, Fano-type resonances have been studied in many physical systems including not only classical atomic systems but also nanophotonic systems such as the field of plasmonics, photonic crystals, and metamaterials due to its unique narrow and asymmetric line shapes nature. [3,4] Recently, Fano-type spectral response in plasmonic nanostructures and metamaterials have attracted considerable attention due to its superior capability to manipulate various characteristics of the Fano resonance in a broad frequency range, which is applicable for practical applications including chemical or biosensing, nonlinear optics, slow light device, and spectroscopy. [5,6] Numerous metallic or dielectric metamateirals have been designed to demonstrate Fano resonances using a common method of breaking the structural symmetry of nanostructures, such as split-ring resonators, [7] asymmetric double bars, [8][9][10] nanoparticle clusters, [11,12] dolmen structures, [13] and hybridized structures. [14][15][16][17] Despite the superior capability of the Fano resonant metamaterials, a trade-off between the quality factor (Q factor) and resonance intensity is unfortunately inevitable. Numerous high Q metamaterials have been proposed so far. [18][19][20] However, as the Q factor increases with an extremely narrow line width, the resonance intensity decreases simultaneously, causing it difficult to detect or distinguish sharp and minute resonances that limit application possibilities. It is an important issue of the high Q metamaterials and is being investigated in a way that defines the Figure of merit (FoM) as the product of the Q factor and intensity. [21] This approach, however, does not solve the tradeoff problem, but suggest only an appropriate region where the two values are moderately high by defining the FoM. The way to resolve the trade-off relation still remains a problem. In addition to the abovementioned problem related to the resonant nature of the Fano resonance, studies for controlling the resonance characteristics are also an important issue since it provides large tunability and flexibility for a variety of practical applications, such as optical sensor, elector-optic modulator, and ultrasensitive Excitation and manipulation of Fano resonances in plasmonic nanostructure have attracted considerable attention due to its capability of degrees of freedom in artificial design especially for spectral positions and quality factors (Q factors). To utilize the high Q factor of Fano resonances in practical applications, their sharp peaks or dips should be well detected, which means a high intensity of resonance line shape. Thus far, the realization of F...

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“…The subwavelength metallic slits used to form asymmetric unit cells in the proposed material, in which waveguide modes are used to concentrate strong electromagnetic fields, can be considered as a Fano system that induces a strong asymmetric resonance . The asymmetric spectral signature of Fano resonances is described as the interference between the localized and propagating surface waves .…”

Section: Introductionmentioning

confidence: 99%

High‐Q Metallic Fano Metamaterial for Highly Efficient Cerenkov Lasing

Kim

Baek

Bhattacharya

et al. 2018

Advanced Optical Materials

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development of such CR-based applications is limited by thermal and dielectric breakdown issues. [3,4] Another limitation is that, due to the velocity threshold, large facilities are required to generate highly energetic particles. These limitations restrict the upper and lower size and performance boundaries in vital applications. Nowadays, metallic metamaterial devices have been proposed, which overcome the limitations of conventional Cerenkov devices to realize reversed CR from the negative-refractive index, [5] the ultralow threshold of kinetic energy in hyperbolic metamaterials, [6] and various metallic metamaterials comprised of subwavelength slits. [7][8][9] However, the realization of a high quality factor (Q) is still an outstanding roadblock for practical Cerenkov devices. Previous works on Cerenkov lasing (CL) using mirrors were limited by a lower electron beam impedance due to the interaction device and the radio-frequency (RF) coupling mechanism. [4,10] Here, to achieve a high Q for highly efficient CL, we focus on maximally trapping the electromagnetic Cerenkov radiation wave to extend its interaction with the electron beam and on controlling the radiation damping, as has been described in Rayleigh scattering to maximize the efficiency of CL. In this paper, we demonstrate that the interplay between an extremely low group velocity from the infinite transverse permittivity of the anisotropic metamaterials and the subradiant A high-quality-factor (high-Q) metallic Fano metamaterial is demonstrated both experimentally and theoretically. This material is suitable for highly efficient Cerenkov lasing in which subwavelength metallic slits are arranged to form asymmetric unit cells. In contrast to conventional dielectric Cerenkov or Smith-Purcell devices, in the proposed device, convection electrons traverse the high-Q metallic metamaterial. The interplay between an extremely low group velocity from the infinite transverse permittivity of the anisotropic metamaterial and the subradiant damping from a Fano-type slit mode is shown to be responsible for the high-Q value, which is measured to be unprecedented at 700. The resulting improvement in the Cerenkov lasing efficiency is estimated to be more than two orders of magnitude using a particle-in-cell simulation.

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Full controlling of Fano resonances in metal-slit superlattice

Cited by 32 publications

References 59 publications

Free-Electron-Driven Multi-Frequency Terahertz Radiation on a Super-Grating Structure

Free-Electron-Driven Multi-Frequency Terahertz Radiation on a Super-Grating Structure

Enhancement and Switching of Fano Resonance in Metamaterial

High‐Q Metallic Fano Metamaterial for Highly Efficient Cerenkov Lasing

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