Symmetry-protected bound states in the continuum supported by all-dielectric metasurfaces

Li, Shiyu; Zhou, Chaobiao; Liu, Tingting; Xiao, Shuyuan

doi:10.1103/physreva.100.063803

Cited by 297 publications

(133 citation statements)

References 54 publications

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“…Further evidence of SP-BIC is represented by the disappearance of a resonance at the symmetry restoring region, where the linewidth becomes zero or quality factor tends to infinity 10,42 . The Q factors of the resonances are calculated as Q = ω 0 /2γ where ω 0 is center resonance frequency and γ is damping rate of the resonance extracted from the equation below 12 TðwÞ…”

Section: Resultsmentioning

confidence: 99%

“…he concept of bound states in the continuum, or BIC, was first proposed by von Neumann and Wigner for an electron in an artificial complex potential 1 . Thereafter, different types of BICs have been reported in quantum systems 2,3 , acoustic and water waves 4,5 and photonic systems [6][7][8][9][10][11][12] , where modes inside the radiation continuum above the light line are perfectly confined instead of radiating away. Due to the infinite quality (Q-) factor and zero linewidth of the BIC modes, only quasi-BICs with partial confinement and finite linewidth are observed experimentally.…”

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confidence: 99%

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Polarization-selective modulation of supercavity resonances originating from bound states in the continuum

et al. 2020

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Bound states in the continuum (BICs) are widely studied for their ability to confine light, produce sharp resonances for sensing applications and serve as avenues for lasing action with topological characteristics. Primarily, the formation of BICs in periodic photonic band gap structures are driven by symmetry incompatibility; structural manipulation or variation of incidence angle from incoming light. In this work, we report two modalities for driving the formation of BICs in terahertz metasurfaces. At normal incidence, we experimentally confirm polarization driven symmetry-protected BICs by the variation of the linear polarization state of light. In addition, we demonstrate through strong coupling of two radiative modes the formation of capacitively-driven Freidrich-Wintgen BICs, exotic modes which occur in off-Γ points not accessible by symmetry-protected BICs. The capacitance-mediated strong coupling at 0° polarization is verified to have a normalized coupling strength ratio of 4.17% obtained by the Jaynes-Cummings model. Furthermore, when the polarization angle is varied from 0° to 90° (0° ≤ ϕ < 90°), the Freidrich-Wintgen BIC is modulated until it is completely switched off at 90°.

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Section: Resultsmentioning

confidence: 99%

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confidence: 99%

Polarization-selective modulation of supercavity resonances originating from bound states in the continuum

et al. 2020

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“…BICs found in slab-type photonic lattices so far can be split into three categories: (i) symmetry-protected BICs, (ii) single-resonance parametric BICs, and (iii) Friedrich-Wintgen BICs. Symmetry-protected BICs appear at the Γ point (the center of the Brillouin zone) due to the symmetry mismatch between their mode profiles and those of external plane waves [29,30]. Single-resonance parametric BICs are found at generic k points along dispersion curves when the relevant coupling to the radiation continuum completely vanishes [31].…”

Section: Introductionmentioning

confidence: 99%

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

2020

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When two nonorthogonal resonances are coupled to the same radiation channel, avoided crossing arises and a bound state in the continuum (BIC) appears with appropriate conditions in parametric space. This paper presents numerical and analytical results on the properties of avoided crossing and BIC due to the coupled guided-mode resonances in one-dimensional (1D) leaky-mode photonic lattices with slab geometry. In symmetric photonic lattices with up-down mirror symmetry, Friedrich–Wintgen BICs with infinite lifetime are accompanied by avoided crossings due to the coupling between two guided modes with the same transverse parity. In asymmetric photonic lattices with broken up-down mirror symmetry, quasi-BICs with finite lifetime appear with avoided crossings because radiating waves from different modes cannot be completely eliminated. We also show that unidirectional-BICs are accompanied by avoided crossings due to guided-mode resonances with different transverse parities in asymmetric photonic lattices. The Q factor of a unidirectional-BIC is finite, but its radiation power in the upward or downward direction is significantly smaller than that in the opposite direction. Our results may be helpful in engineering BICs and avoided crossings in diverse photonic systems that support leaky modes.

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“…One such example is a normally incident plane wave or Gaussian beam and a high-contrast grating with an antisymmetric mode at its gamma point, that is, wavevector k = 0. The inability of an even symmetry incident wave to couple to an odd symmetry device mode is the working principle of a so-called symmetry-protected BIC [28]. Coupling to such a resonance therefore requires either the breaking of the even symmetry of the incident beam or of the odd symmetry of the mode, a process that results in a state that is quasi-bound in the continuum (a quasi-BIC).…”

Section: Device Principlesmentioning

confidence: 99%

Enhanced harmonic generation in gases using an all-dielectric metasurface

et al. 2020

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Strong field confinement, long-lifetime resonances, and slow-light effects suggest that metasurfaces are a promising tool for nonlinear optical applications. These nanostructured devices have been utilized for relatively high efficiency solid-state high-harmonic generation platforms, four-wave mixing, and Raman scattering experiments, among others. Here, we report the first all-dielectric metasurface to enhance harmonic generation from a surrounding gas, achieving as much as a factor of 45 increase in the overall yield for Argon atoms. When compared to metal nanostructures, dielectrics are more robust against damage for high power applications such as those using atomic gases. We employ dimerized high-contrast gratings fabricated in silicon-on-insulator that support bound states in the continuum, a resonance feature accessible in broken-symmetry planar devices. Our 1D gratings maintain large mode volumes, overcoming one of the more severe limitations of earlier device designs and greatly contributing to enhanced third- and fifth-harmonic generation. The interaction lengths that can be achieved are also significantly greater than the 10’s of nm to which earlier solid-state designs were restricted. We perform finite-difference time-domain simulations to fully characterize the wavelength, linewidth, mode profile, and polarization dependence of the resonances. Our experiments confirm these predictions and are consistent with other nonlinear optical properties. The tunable wavelength dependence and quality factor control we demonstrate in these devices make them an attractive tool for the next generation of high-harmonic sources, which are anticipated to be pumped at longer wavelengths and with lower peak power, higher repetition rate lasers.

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Symmetry-protected bound states in the continuum supported by all-dielectric metasurfaces

Cited by 297 publications

References 54 publications

Polarization-selective modulation of supercavity resonances originating from bound states in the continuum

Polarization-selective modulation of supercavity resonances originating from bound states in the continuum

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

Enhanced harmonic generation in gases using an all-dielectric metasurface

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