Bound states in the continuum (BIC) accompanied by avoided crossings in leaky-mode photonic lattices

Lee, Sun-Goo; Kim, Seong Han; Kee, Chul‐Sik

doi:10.1515/nanoph-2020-0346

Cited by 72 publications

(44 citation statements)

References 43 publications

(42 reference statements)

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“…Parameter 𝑘 denotes the internal (near-field) coupling strength between the modes and √ 𝛾 1 𝛾 2 is the radiative coupling term, while 𝜓 is the phase difference between two modes. Therefore parameter 𝑒 𝑖𝜓 √ 𝛾 1 𝛾 2 represents the interference of radiating waves through far-field coupling [22]. The eigenvalues of Hamiltonian (1) are determined by the secular equation and have the following form:…”

Section: Friedrich-wintgen Modelmentioning

confidence: 99%

“…In this work, we will be interested in the third type of quasi-BIC. This type of quasi-BIC occurs when two non-orthogonal modes are coupled to the same radiation channel and a strong-coupling regime of avoided crossing arises with appropriate conditions in parametric space [10,12,[20][21][22][23]. This regime is described by the Friedrich-Wintgen model [24] when due to destructive interference one of the emitting modes disappears and the other becomes more lossy due to constructive interference.…”

Section: Introductionmentioning

confidence: 99%

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Bound states in the continuum in strong-coupling and weak-coupling regimes under the cylinder – ring transition

et al. 2021

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Bound states in the continuum (BIC) have been at the forefront of research in optics and photonics over the past decade. It is of great interest to study the effects associated with quasi-BICs in the simplest structures, where quasi-BICs are very pronounced. An example is a dielectric cylinder, and in a number of works, quasi-BICs have been studied both in single cylinders and in structures composed of cylinders. In this work, we studied the properties of quasi-BICs during the transition from a homogeneous dielectric cylinder in an air environment to a ring with narrow walls while increasing the diameter of the inner air cylinder gradually. The results demonstrate the quasi-BIC crossover from the strong-coupling to the weak-coupling regime, which manifests itself in the transition from the avoided crossing of branches to their intersection with the quasi-BIC being preserved on only one straight branch. In the regime of strong-coupling and quasi-BIC, three waves interfere in the far-field zone: two waves corresponding to the resonant modes of the structure and the wave scattered by the structure as a whole. The validity of the Fano resonance concept is discussed since it describes the interference of only two waves under weak coupling conditions.

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Section: Friedrich-wintgen Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Bound states in the continuum in strong-coupling and weak-coupling regimes under the cylinder – ring transition

et al. 2021

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“…Thus, Bands 2 and 3 repel each other near k x / K ¼ 0.36. [24,25] Band 4 is a W-shaped dispersion, resulted from the dispersion of the solitary HCG. The characteristics of the four dispersion curves will be studied in detail in the following sections.…”

Section: Hcg-dbr-based Metastructure and Its Dispersionsmentioning

confidence: 99%

Dispersion Engineering for a Metastructure Composed of a High‐Contrast Subwavelength Grating and a Distributed Bragg Reflector

Zhang

Liu

2021

Advanced Photonics Research

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High‐contrast subwavelength grating (HCG) and distributed Bragg reflector (DBR) are demonstrated to be able to tailor the dispersion independently. Herein, it is found that multiple‐shape dispersions can be realized by a metastructure, which consists of an HCG on the DBR. Such a simple structure exhibits the linear dispersions with band‐edge modes, the M‐shaped dispersion with a cavity mode, and the W‐shaped dispersion with a bound state in the continuum. The origins of these dispersions and the mode characteristics (field distribution and quality factor) in the dispersions are studied. This study is helpful to realize single‐mode high‐efficiency surface‐emitting lasers, optical sensors, and quantum electrodynamics.

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“…Bound states in the continuum (BICs) are special nonradiating states with an infinite lifetime [ 48 , 49 , 50 , 51 , 52 ] that were first introduced in quantum systems in 1929 by von Neumann and Wigner [ 53 ]. In recent years, BICs are also widely found in all-dielectric metasurfaces [ 54 , 55 , 56 , 57 , 58 , 59 , 60 ].…”

Section: Introductionmentioning

confidence: 99%

Manipulating Optical Scattering of Quasi-BIC in Dielectric Metasurface with Off-Center Hole

Zhou

Huang

et al. 2021

Nanomaterials

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Bound states in the continuum (BICs) correspond to a particular leaky mode with an infinitely large quality-factor (Q-factor) located within the continuum spectrum. To date, most of the research work reported focuses on the BIC-enhanced light matter interaction due to its extreme near-field confinement. Little attention has been paid to the scattering properties of the BIC mode. In this work, we numerically study the far-field radiation manipulation of BICs by exploring multipole interference. By simply breaking the symmetry of the silicon metasurface, an ideal BIC is converted to a quasi-BIC with a finite Q-factor, which is manifested by the Fano resonance in the transmission spectrum. We found that both the intensity and directionality of the far-field radiation pattern can not only be tuned by the asymmetric parameters but can also experience huge changes around the resonance. Even for the same structure, two quasi-BICs show a different radiation pattern evolution when the asymmetric structure parameter d increases. It can be found that far-field radiation from one BIC evolves from electric-quadrupole-dominant radiation to toroidal-dipole-dominant radiation, whereas the other one shows electric-dipole-like radiation due to the interference of the magnetic dipole and electric quadrupole with the increasing asymmetric parameters. The result may find applications in high-directionality nonlinear optical devices and semiconductor lasers by using a quasi-BIC-based metasurface.

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Bound states in the continuum (BIC) accompanied by avoided crossings in leaky-mode photonic lattices

Cited by 72 publications

References 43 publications

Bound states in the continuum in strong-coupling and weak-coupling regimes under the cylinder – ring transition

Bound states in the continuum in strong-coupling and weak-coupling regimes under the cylinder – ring transition

Dispersion Engineering for a Metastructure Composed of a High‐Contrast Subwavelength Grating and a Distributed Bragg Reflector

Manipulating Optical Scattering of Quasi-BIC in Dielectric Metasurface with Off-Center Hole

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