Toroidal dipole Fano resonances supported by lattice-perturbed dielectric nanohole arrays in the near-infrared region

Song, Duofu; Wang, Hong; Deng, Meng; Wang, Yi

doi:10.1364/ao.422295

Cited by 9 publications

(3 citation statements)

References 50 publications

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“…Electrons, electric quadrupoles

, and magnetic quadrupoles

can be ignored due to the small contribution of higher-order multipoles. The multipole moment is defined as [ 42 , 43 , 44 ]

where j is the current density vector, r is the position vector, c is the speed of light, ω is the angular frequency, α , β = x , y , z . The scattered power for multipole momentum can be calculated by

…”

Section: Resultsmentioning

confidence: 99%

High-Sensitivity Sensing in All-Dielectric Metasurface Driven by Quasi-Bound States in the Continuum

et al. 2023

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Quasi-bound states in the continuum (quasi-BIC) in all-dielectric metasurfaces provide a crucial platform for sensing due to its ability to enhance strong matter interactions between light-waves and analytes. In this study, a novel high-sensitivity all-dielectric sensor composed of a periodic array of silicon (Si) plates with square nanoholes in the continuous near-infrared band is theoretically proposed. By adjusting the position of the square nanohole, the symmetry-protected BIC and Friedrich–Wintgen BIC (FW–BIC) can be excited. The torodial dipole (TD) and electric quadruple (EQ) are demonstrated to play a dominating role in the resonant modes by near-field analysis and multipole decomposition. The results show that the sensitivity, the Q-factor, and the corresponding figure of merit (FOM) can simultaneously reach 399 nm/RIU (RIU is refractive index unit), 4959, and 1281, respectively. Compared with other complex nanostructures, the proposed metasurface is more feasible and practical, which may open up an avenue for the development of ultrasensitive sensors.

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“…Electrons, electric quadrupoles

, and magnetic quadrupoles

can be ignored due to the small contribution of higher-order multipoles. The multipole moment is defined as [ 42 , 43 , 44 ]

…”

Section: Resultsmentioning

confidence: 99%

High-Sensitivity Sensing in All-Dielectric Metasurface Driven by Quasi-Bound States in the Continuum

et al. 2023

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show abstract

“…However, when n = 1.0001, the GH shift (ϴ = 2°) is 37.14 μm (the resonance wavelength λ0 (n = 1.0001) = 977.187 nm). The sensor sensitivity, which is defined as S = ΔGH/Δn, is calculated to be 3.58 × 10 6 μm/RIU, which is much From Figure 2b, it can be seen that the narrow linewidth Fano resonance formed by the metasurface has a high Q value when d = 0 nm, which indicates that the metasurface has ultra-high sensitivity when used as a sensor [39]. For this reason, we apply this to refractive index (RI) sensing to detect any small changes in the environmental refractive index.…”

Section: Theoretical Calculation Of Gh Shiftmentioning

confidence: 95%

“…Therefore, their changes have a smaller impact on the GH shift of the metasurface. From Figure 2b, it can be seen that the narrow linewidth Fano resonance formed by the metasurface has a high Q value when d ≠ 0 nm, which indicates that the metasurface has ultra-high sensitivity when used as a sensor [39]. For this reason, we apply this to refractive index (RI) sensing to detect any small changes in the environmental refractive index.…”

Section: Theoretical Calculation Of Gh Shiftmentioning

confidence: 99%

Theoretical Enhancement of the Goos–Hänchen Shift with a Metasurface Based on Bound States in the Continuum

2023

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The enhancement of the Goos–Hänchen (GH) shift has become a research hotspot due to its promoted application of the GH effect in various fields. However, currently, the maximum GH shift is located at the reflectance dip, making it difficult to detect GH shift signals in practical applications. This paper proposes a new metasurface to achieve reflection-type bound states in the continuum (BIC). The GH shift can be significantly enhanced by the quasi-BIC with a high quality factor. The maximum GH shift can reach more than 400 times the resonant wavelength, and the maximum GH shift is located exactly at the reflection peak with unity reflectance, which can be applied to detect the GH shift signal. Finally, the metasurface is used to detect the variation in the refractive index, and the sensitivity can reach 3.58 × 106 μm/RIU (refractive index unit) according to the simulation’s calculations. The findings provide a theoretical basis to prepare a metasurface with high refractive index sensitivity, a large GH shift, and high reflection.

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High-Q magnetic toroidal dipole resonance in all-dielectric metasurfaces

Zhang,

Wang,

et al. 2024

APL Photonics

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High quality (Q) factor toroidal dipole (TD) resonances have played an increasingly important role in enhancing light–matter interactions. Interestingly, TDs share a similar far-field distribution as the conventional electric/magnetic dipoles but have distinct near-field profiles from them. While most reported works focused on the electric TD, magnetic TDs (MTDs), particularly high-Q MTD, have not been fully explored yet. Here, we successfully realized a high-Q MTD by effectively harnessing the ultrahigh Q-factor guided mode resonances supported in an all-dielectric metasurface, that is, changing the interspacing between silicon nanobar dimers. Other salient properties include the stable resonance wavelength but a precisely tailored Q-factor by interspacing distance. A multipole decomposition analysis indicates that this mode is dominated by the MTD, where the electric fields are mainly confined within the dielectric nanostructures, while the induced magnetic dipole loops are connected head-to-tail. Finally, we experimentally demonstrated such high-Q MTD resonance by fabricating a series of silicon metasurfaces and measuring their transmission spectra. The MTD resonance is characterized by a sharp Fano resonance in the transmission spectrum. The maximum measured Q-factor is up to 5079. Our results provide useful guidance for realizing high-Q MTD and may find exciting applications in boosting light–matter interactions.

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Toroidal dipole Fano resonances supported by lattice-perturbed dielectric nanohole arrays in the near-infrared region

Cited by 9 publications

References 50 publications

High-Sensitivity Sensing in All-Dielectric Metasurface Driven by Quasi-Bound States in the Continuum

High-Sensitivity Sensing in All-Dielectric Metasurface Driven by Quasi-Bound States in the Continuum

Theoretical Enhancement of the Goos–Hänchen Shift with a Metasurface Based on Bound States in the Continuum

High-Q magnetic toroidal dipole resonance in all-dielectric metasurfaces

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