Multipolar origin of bound states in the continuum

Sadrieva, Z. F.; Frizyuk, Kristina; Petrov, Mihail; Kivshar, Yuri S.; Bogdanov, Andrey

doi:10.1103/physrevb.100.115303

Cited by 229 publications

(131 citation statements)

References 98 publications

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“…In the latter, lasing is achieved by modifying one of the lattice constants to allow for an off-normal diffraction channel. Otherwise, it should be mentioned that complex multipolar have been proposed very recently to enforce off-normal cancellation for accidental BICs 17 .…”

Section: Introductionmentioning

confidence: 99%

Brewster quasi bound states in the continuum in all-dielectric metasurfaces from single magnetic-dipole resonance meta-atoms

Abujetas

Barreda

Moreno

et al. 2019

Sci Rep

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Bound states in the continuum (BICs) are ubiquitous in many areas of physics, attracting special interest for their ability to confine waves with infinite lifetimes. Metasurfaces provide a suitable platform to realize them in photonics; such BICs are remarkably robust, being however complex to tune in frequency-wavevector space. Here we propose a scheme to engineer BICs and quasi-BICs with single magnetic-dipole resonance meta-atoms. Upon changing the orientation of the magnetic-dipole resonances, we show that the resulting quasi-BICs, emerging from the symmetry-protected BIC at normal incidence, become transparent for plane-wave illumination exactly at the magnetic-dipole angle, due to a Brewster-like effect. While yielding infinite Q-factors at normal incidence (canonical BIC), these are termed Brewster quasi-BICs since a transmission channel is always allowed that slightly widens resonances at oblique incidences. This is demonstrated experimentally through reflectance measurements in the microwave regime with high-refractive-index mm-disk metasurfaces. Such Brewster-inspired configuration is a plausible scenario to achieve quasi-BICs throughout the electromagnetic spectrum inaccessible through plane-wave illumination at given angles, which could be extrapolated to other kind of waves.

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Section: Introductionmentioning

confidence: 99%

Brewster quasi bound states in the continuum in all-dielectric metasurfaces from single magnetic-dipole resonance meta-atoms

Abujetas

Barreda

Moreno

et al. 2019

Sci Rep

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“…The latter have been proved to be highly robust against input beam collimation and nanostructure extension in lasing applications [23] and surface-enhanced fluorescence microscopy [24]. Very recent advances of BIC phenomeon include electromagnetic multipole theory interpretation [28] and momentum space merging of multiple bound states [29]. Recently, in-plane symmetry breaking for engineering and tuning of quasi-BIC modes with designer architectures of photonic crystal slabs [30] and metasurfaces [31,32] have also been proposed and applied for hyperspectral biomolecular detection.…”

Section: Introductionmentioning

confidence: 99%

Tuning the exponential sensitivity of a bound-state-in-continuum optical sensor

Romano¹,

Zito²,

Yépez³

et al. 2019

Opt. Express

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In this work, we investigate the evanescent field sensing mechanism provided by an all-dielectric metasurface supporting bound states in the continuum (BICs). The metasurface is based on a transparent photonic crystal with subwavelength thickness. The BIC electromagnetic field is localized along the direction normal to the photonic crystal nanoscale-thin slab (PhCS) because of a topology-induced confinement, exponentially decaying in the material to detect. On the other hand, it is totally delocalized in the PhCS plane, which favors versatile and multiplexing sensing schemes. Liquids with different refractive indices, ranging from 1.33 to 1.45, are infiltrated in a microfluidic chamber bonded to the sensing dielectric metasurface. We observe an experimental exponential sensitivity leading to differential values as large as 226 nm/RIU with excellent FOM. This behavior is explained in terms of the physical superposition of the field with the material under investigation and supported by a thorough numerical analysis. The mechanism is then translated to the case of molecular adsorption where a suitable theoretical engineering of the optical structure points out potential sensitivities as large as 4000 nm/RIU.

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“…Comprehensive schematic representations of the formation mechanisms of symmetry protected (at-Γ) and accidental (off-Γ) BICs are depicted in the top and bottom rows of Figure 1b. [39] Multipolar expansion of the Γ-point BICs: if a single unit cell consists only of the multipoles that do not radiate along the z-axis, then apparently, there is no total radiation in the z direction ( Figure 1b, top row). Analyzing the multipoles, the authors in ref.…”

Section: Multipole Approach To the Bic-based Meta-elementsmentioning

confidence: 99%

Photonic Bound States in the Continuum: From Basics to Applications

Azzam

Kildishev

2020

Advanced Optical Materials

363

141

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In theory, BICs are dark states with infinite radiative lifetime and generally require at least one dimension of the structure extending to infinity. [6] Similar conditions can also be obtained in localized systems of finite extent when the permittivity approaches zero. [5,11] However, in practice, due to the finite extent of structures, material absorption, and other external perturbations, BICs collapse to a Fano resonance with a limited radiative Q factor. Such resonances are known as quasi-BIC and they have been used to obtain very high Q resonances in numerous photonic systems to date. [6,8,12] Even though practical implementations of BICs are limited to quasi-BIC, in the literature, as well as in this review, quasi-BIC are commonly referred to as BICs. Another type of high-Q resonances called near-BIC is obtained in the vicinity of the BIC through detuning the system from the BIC regime. [9,13,14] Near-BICs can be explained by the Theory of Resonance Reactions by Fonda [13,14] as a bound state can exist in the continuum at an energy where some channels are open even when the open and closed channels are strongly coupled. If the Hamiltonian of the system differs slightly from the one that can produce such a bound state, a sharp resonance appears in all scattering and reaction cross-sections. Near-BIC resonances can be obtained over an interval of values of a specific parameter of the system, unlike BICs that are generally achieved at a single value of the parameter. [9,15] This is of importance for practical systems as it provides stability to fabrication errors and other imperfections. [12] It is also worth mentioning that the total Q factor (Q t) realizable through BICs is generally limited by the material loss. While the radiative Q-factor (Q r) at BICs can diverge, the non-radiative Q-factor (Q nr) is limited by material absorption and its inhomogeneous broadening, scattering from the structural disorder, and in-plane lateral leakage. It is therefore, important to have an accurate distinction between Q r and Q nr and account for non-radiative processes as generally the main contributors to the total Q." 1.2. BIC Types and Formation Mechanisms Since the time of initial prediction of BICs in photonics, they have been realized in numerous geometrical systems, including gratings, waveguides, metasurfaces, and photonic crystals. [4,7,9,16-24] Such a broad diversity of photonic systems supports different types of BICs that originate from various physical mechanisms. We will briefly highlight the different The introduction of bound states in the continuum (BICs) to photonics has revolutionized the way cavity design and light-matter interactions are thought about in general. BICs can have very high quality factors, even in open structures where access to radiation is permissible. Now, BICs found applications in a large class of areas, including nonlinear enhancement, coherent light generation, sensors, filters, integrated circuits, and many others. In this review, the different types of BICs in photonic systems,...

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Multipolar origin of bound states in the continuum

Cited by 229 publications

References 98 publications

Brewster quasi bound states in the continuum in all-dielectric metasurfaces from single magnetic-dipole resonance meta-atoms

Brewster quasi bound states in the continuum in all-dielectric metasurfaces from single magnetic-dipole resonance meta-atoms

Tuning the exponential sensitivity of a bound-state-in-continuum optical sensor

Photonic Bound States in the Continuum: From Basics to Applications

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