From Fano to Quasi-BIC Resonances in Individual Dielectric Nanoantennas

Melik-Gaykazyan, Elizaveta V.; Koshelev, Kirill; Choi, Jae Hyuck; Kruk, Sergey; Bogdanov, Andrey; Park, Hong Gyu; Kivshar, Yuri S.

doi:10.1021/acs.nanolett.0c04660

Cited by 118 publications

(60 citation statements)

References 55 publications

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“…Symmetric shape of the resonances in Fig. 4(d) is a distinctive feature of quasi-BICs as verified experimentally for individual nanoparticles [67]. A small blue shift of the quasi-BIC resonance evident from Fig.…”

supporting

confidence: 76%

Quasi-bound states in the continuum induced by $\mathcal{PT}$-symmetry breaking

Novitsky,

Shalin,

Redka

et al. 2021

Preprint

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Bound states in the continuum (BICs) enable unique features in tailoring light-matter interaction on nanoscale. These radiationless localized states drive theoretically infinite quality factors and lifetimes for modern nanophotonics, making room for a variety of emerging applications. Here we, for the first time, pave a way from the recent developments in non-Hermitian photonics and peculiar properties possessed by the so-called PTsymmetric optical structures to novel mechanism for the quasi-BIC manifestation governed by the PTsymmetry breaking. In particular, we study regularities of the spontaneous PT -symmetry breaking in trilayer structures with the outer loss and gain layers consisting of materials with permittivity close to zero. We reveal singular points on the curves separating PT -symmetric and broken-PT -symmetry states in the parametric space of the light frequency and the angle of incidence. These singularities remarkably coincide with the BIC positions at the frequency of volume plasmon excitation, where the dielectric permittivity vanishes. The loss and gain value acts as an asymmetry parameter that disturbs conditions of the ideal BIC inducing the quasi-BIC. Fascinating properties of these quasi-BICs having ultrahigh quality factors and almost perfect transmission can be utilized in sensing, nonlinear optics, and other applications.

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supporting

confidence: 76%

Quasi-bound states in the continuum induced by $\mathcal{PT}$-symmetry breaking

Novitsky,

Shalin,

Redka

et al. 2021

Preprint

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“…In order to verify our general analysis and theoretical findings, we conduct nonlinear spectroscopy from the dimers of two AlGaAs nanoparticles fabricated by a consequent transfer of individual nanoparticles on a glass substrate as described earlier [60]. The dimers are formed (see an SEM picture in Fig.…”

Section: B Shg For Nanoparticle Dimersmentioning

confidence: 81%

Nonlinear circular dichroism in Mie-resonant nanoparticle dimers

Frizyuk,

Melik-Gaykazyan,

Choi

et al. 2021

Preprint

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We study nonlinear response of a dimer composed of two identical Mie-resonant dielectric nanoparticles illuminated normally by a circularly polarized light. We develop a general theory describing hybridization of multipolar modes of the coupled nanoparticles, and reveal nonvanishing nonlinear circular dichroism (CD) in the second-harmonic generation (SHG) signal enhanced by the multipolar resonances in the dimer provided its axis is oriented under an angle to the crystalline lattice of the dielectric material. We present experimental results for this SHG-CD effect obtained for the AlGaAs dimers placed on an engineered substrate which confirm the basic prediction of our general multipolar hybridization theory.

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“…1d) transforms BIC into quasi-BIC supporting high-Q leaky resonant modes 12 manifested in the transmission spectra as sharp Fano resonances. 44 We design the metasurface to support this high-Q mode in the telecom spectral range (1400 − 1600 nm) by making the bars in the unit cell w 1 = 230 nm wide (Fig. 1d).…”

Section: Resultsmentioning

confidence: 99%

Observation of Ultrafast Self-Action Effects in Quasi-BIC Resonant Metasurfaces

et al. 2021

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High-index dielectric metasurfaces can support sharp optical resonances enabled by the physics of bound states in the continuum (BICs) often manifested in experiment as quasi-BIC resonances. They provide an efficient way to enhance light-matter interaction at the subwavelength scale bringing novel opportunities for nonlinear nanophotonics. Strong narrow-band field enhancement in quasi-BIC metasurfaces leads to an extreme sensitivity to a change of the refractive index that may limit nonlinear functionalities for the pump intensities beyond the perturbative regime. Here we study ultrafast self-action effects observed in quasi-BIC silicon metasurfaces with meta-atoms characterized by a broken in-plane symmetry. We demonstrate how the self-action effects can alter the power dependence of the third-harmonic generation efficiency. We study experimentally a transition from the super-cubic to sub-cubic regimes for the generated third-harmonic power, and measure a blue-shift of the third-harmonic signal on subpicosecond scales in the multiphoton absorption regime. We observe a sharp increase of the third-harmonic linewidth with a growth of the peak pump intensity above the threshold of 10 GW/cm 2 . Our results suggest a direct way to implement ul-trafast nonlinear dynamics in high-index resonant dielectric metasurfaces for nonlinear metaoptics beyond the perturbative regime.

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From Fano to Quasi-BIC Resonances in Individual Dielectric Nanoantennas

Cited by 118 publications

References 55 publications

Quasi-bound states in the continuum induced by $\mathcal{PT}$-symmetry breaking

Quasi-bound states in the continuum induced by $\mathcal{PT}$-symmetry breaking

Nonlinear circular dichroism in Mie-resonant nanoparticle dimers

Observation of Ultrafast Self-Action Effects in Quasi-BIC Resonant Metasurfaces

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