Multipolar properties of guide resonances

He, Yuan; Guo, Guangtao; Feng, Tianhua; Xu, Yi; Miroshnichenko, Andrey E.

doi:10.1364/cleopr.2018.w3a.6

Cited by 4 publications

(9 citation statements)

References 4 publications

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“…In order to verify the validity of the multipolar expansion analysis, we also reconstructed the transmission spectrum of the quasi-BIC with a modified multipole decomposition method. 46 As shown in Figure 1e, the reconstructed transmission spectrum is qualitatively in agreement with that obtained in the numerical simulation. In order to see the influence of the scaling factor s on the lineshape of the quasi-BIC, we show the transmission spectra of the metasurfaces with different values of s in a moderate wavelength range in Figure 1f.…”

Section: ■ Results and Discussionsupporting

confidence: 84%

“…In addition, the transmission and reflection spectra of the metasurface can be reconstructed. 46 Here, one can see an asymmetric Fano lineshape located at ∼1330 nm, which is governed by MD in the z direction (i.e., MD z ). In this case, the intensities of the broad modes (ED y and MD x ) are 3 orders of magnitude weaker than that of the narrow mode (MD z ).…”

Section: ■ Results and Discussionmentioning

confidence: 94%

“…It is generally accepted that symmetry-protected BICs cannot be excited unless the symmetry is broken. 40,44,46 In addition, it is found that the Q factor of a quasi-BIC decreases exponentially with increasing asymmetry. 37 However, a dielectric nanoparticle with a finite size may simultaneously support multiple modes which are not isolated from each other.…”

Section: ■ Introductionmentioning

confidence: 99%

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Modifying the Quality Factors of the Bound States in the Continuum in a Dielectric Metasurface by Mode Coupling

Zhou

Liu

et al. 2022

ACS Photonics

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As optical resonances with high-quality (Q) factors, bound states in the continuum (BICs) supported in a metamaterial with low optical loss have attracted great interest due to their potential applications in photonic devices with different functionalities. However, most studies focus on the influence of the symmetry breaking in the constituent elements on the Q factors of the quasi-BICs, and less attention is paid to the coupling between the constituent elements. Here, we investigate numerically and experimentally the quasi-BICs revealed in metasurfaces composed of regularly arranged silicon (Si) nanoparticles with and without a geometric symmetry. It is found that the quasi-BICs appear in the transmission spectra of the metasurfaces as Fano lineshapes with different asymmetry parameters, depending strongly on the relative locations of the two optical modes involved in the interference. Apart from symmetry-protected BICs dominated by optical modes that radiate only in the direction parallel to the metasurface, accidental BICs at-Γ formed by the destructive interference of two optical modes are also revealed. The leakage of the quasi-BICs in the direction of light incidence originates from the interference of such modes with other optical modes existing in the same spectral range, which limits the maximum Q factors of the quasi-BICs. Consequently, quasi-BICs with high-Q factors (10 10 to 10 13 ) are also observed in metasurfaces composed of Si nanoparticles with geometric symmetry (or without symmetry breaking). More interestingly, the Q factors of the quasi-BICs in a metasurface composed of Si nanoparticles with symmetry breaking exhibit a strong dependence on the period of the metasurface. An exponential decrease of the Q factor is observed when the period of the metasurface deviates from the value at which the maximum Q factor is achieved, implying the crucial role of mode coupling in determining the Q factor. As a result, the Q factor of a quasi-BIC may not decrease exponentially when the symmetry breaking of the Si nanoparticle is increased. In comparison, the quasi-BICs in a metasurface composed of Si nanoparticles with geometric symmetry are not sensitive to the period of the metasurface. By deliberately choosing the period, the maximum Q factors of the quasi-BICs achieved in the metasurface with symmetry breaking are close to those realized in the metasurface without symmetry breaking. Our findings are important for understanding the physical origin of the so-called symmetry-protected BICs supported by metasurfaces and helpful for designing photonic devices based on quasi-BICs.

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Section: ■ Results and Discussionsupporting

confidence: 84%

Section: ■ Results and Discussionmentioning

confidence: 94%

Section: ■ Introductionmentioning

confidence: 99%

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Modifying the Quality Factors of the Bound States in the Continuum in a Dielectric Metasurface by Mode Coupling

Zhou

Liu

et al. 2022

ACS Photonics

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“…Indeed, ordered arrays of silicon nanopillars arranged in a peculiar resonant configuration can support quadrupolar quasi-BIC modes with huge Q-factors (up to Q = 10 9 ) in the NIR spectral range. 24,26,27 Thanks to the slotted nanoantenna geometry, in the present work we have exploited quasi-BIC resonances to boost the Er 3+ radiative emission. Figure 2a shows the PL emission spectrum in the 1400−1650 nm wavelength range for the sample with r = 360 nm and a 0 = 800 nm.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Quasi-BIC Modes in All-Dielectric Slotted Nanoantennas for Enhanced Er³⁺ Emission

Kalinic¹,

Cesca²,

Balasa³

et al. 2023

ACS Photonics

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In the quest for new and increasingly efficient photon sources, the engineering of the photonic environment at the subwavelength scale is fundamental for controlling the properties of quantum emitters. A high refractive index particle can be exploited to enhance the optical properties of nearby emitters without decreasing their quantum efficiency, but the relatively modest Q-factors (Q ∼ 5− 10) limit the local density of optical states (LDOS) amplification achievable. On the other hand, ultrahigh Q-factors (up to Q ∼ 10 9 ) have been reported for quasi-BIC modes in all-dielectric nanostructures. In the present work, we demonstrate that the combination of quasi-BIC modes with high spectral confinement and nanogaps with spacial confinement in silicon slotted nanoantennas lead to a significant boosting of the electromagnetic LDOS in the optically active region of the nanoantenna array. We observe an enhancement of up to 3 orders of magnitude in the photoluminescence intensity and 2 orders of magnitude in the decay rate of the Er 3+ emission at room temperature and telecom wavelengths. Moreover, the nanoantenna directivity is increased, proving that strong beaming effects can be obtained when the emitted radiation couples to the high Q-factor modes. Finally, via tuning the nanoanntenna aspect ratio, a selective control of the Er 3+ electric and magnetic radiative transitions can be obtained, keeping the quantum efficiency almost unitary.

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“…Dielectric metasurfaces are typically composed of high-index dielectric resonators integrated on low-index substrates (e.g., silicon nanodisks on a quartz substrate). 24,26,32,33 Unfortunately, the thickness of the substrate is usually comparable to the wavelength of interest at terahertz frequencies, introducing interference effects. Moreover, the electromagnetic response can be affected by the dielectric contrast between the resonators and the substrate.…”

Section: ■ Introductionmentioning

confidence: 99%

Broadband Terahertz Silicon Membrane Metasurface Absorber

et al. 2022

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Metasurface absorbers are of particular interest in numerous photonic applications including detectors, photovoltaic cells, and emissivity coatings. We introduce a thin membrane silicon metasurface absorber with periodic elliptical holes that, as demonstrated theoretically and experimentally, achieves very high absorption (≥90%) over a ∼500 GHz bandwidth at normal incidence. Based on the analysis of the effective medium theory, the broadband absorption is attributed to proximal electric and magnetic dipole resonances. The absorption amplitude can also be tuned by ∼20% with above-gap photoexcitation. Due to the unit cell geometry, the carrier density on the top surface and sidewalls of the membrane must be taken into account. Our dynamic membrane silicon metasurface absorber is notably thin and CMOS-compatible, providing a promising platform to realize compact terahertz devices including detectors, modulators, and switches.

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Multipolar properties of guide resonances

Cited by 4 publications

References 4 publications

Modifying the Quality Factors of the Bound States in the Continuum in a Dielectric Metasurface by Mode Coupling

Modifying the Quality Factors of the Bound States in the Continuum in a Dielectric Metasurface by Mode Coupling

Quasi-BIC Modes in All-Dielectric Slotted Nanoantennas for Enhanced Er³⁺ Emission

Broadband Terahertz Silicon Membrane Metasurface Absorber

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Multipolar properties of guide resonances

Cited by 4 publications

References 4 publications

Modifying the Quality Factors of the Bound States in the Continuum in a Dielectric Metasurface by Mode Coupling

Modifying the Quality Factors of the Bound States in the Continuum in a Dielectric Metasurface by Mode Coupling

Quasi-BIC Modes in All-Dielectric Slotted Nanoantennas for Enhanced Er3+ Emission

Broadband Terahertz Silicon Membrane Metasurface Absorber

Contact Info

Product

Resources

About

Quasi-BIC Modes in All-Dielectric Slotted Nanoantennas for Enhanced Er³⁺ Emission