Photonic Bound States in the Continuum in Nanostructures

Zhong, Hongkun; He, Tiantian; Meng, Yuan; Xiao, Qirong

doi:10.3390/ma16227112

Cited by 2 publications

(1 citation statement)

References 245 publications

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“…Bound state in the continuum (BIC) is a wave that remains localized even though it coexists with a continuous spectrum of the radiation wave that can carry energy away [ 22 ], i.e., it is an eigenmode without electromagnetic energy leakage [ 23 , 24 ], and hence its theoretical Q factor can reach infinity. While Quasi-bound state in the continuum (QBIC) makes a small portion of the electromagnetic energy leakage to the far field by introducing a structural asymmetry into the BIC mode [ 25 ], by controlling the asymmetry, it is possible to control the degree of electromagnetic energy leakage and thus actively regulate the Q factor [ 26 , 27 , 28 ], which provides an important idea of designing metamaterials sensors with adjustable high Q factors.…”

Section: Introductionmentioning

confidence: 99%

Detection of Low-Concentration Biological Samples Based on a QBIC Terahertz Metamaterial Sensor

Dong,

Wei,

Wei

et al. 2024

Sensors

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Quasi-bound state in the continuum (QBIC) can effectively enhance the interaction of terahertz (THz) wave with matter due to the tunable high-Q property, which has a strong potential application in the detection of low-concentration biological samples in the THz band. In this paper, a novel THz metamaterial sensor with a double-chain-separated resonant cavity structure based on QBIC is designed and fabricated. The process of excitation of the QBIC mode is verified and the structural parameters are optimized after considering the ohmic loss by simulations. The simulated refractive index sensitivity of the sensor is up to 544 GHz/RIU, much higher than those of recently reported THz metamaterial sensors. The sensitivity of the proposed metamaterial sensor is confirmed in an experiment by detecting low-concentration lithium citrate (LC) and bovine serum albumin (BSA) solutions. The limits of detection (LoDs) are obtained to be 0.0025 mg/mL (12 μM) for LC and 0.03125 mg/mL (0.47 μM) for BSA, respectively, both of which excel over most of the reported results in previous studies. These results indicate that the proposed THz metamaterial sensor has excellent sensing performances and can well be applied to the detection of low-concentration biological samples.

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Section: Introductionmentioning

confidence: 99%

Detection of Low-Concentration Biological Samples Based on a QBIC Terahertz Metamaterial Sensor

Dong,

Wei,

Wei

et al. 2024

Sensors

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Efficient polarization-insensitive quasi-BIC modulation by VO₂ thin films

Zhong,

He,

Wang

et al. 2024

Opt. Express

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Bound states in the continuum (BIC) offer great design freedom for realizing high-quality factor metasurfaces. By deliberately disrupting the inherent symmetries, BIC can degenerate into quasi-BIC exhibiting sharp spectra with strong light confinement. This transformation has been exploited to develop cutting-edge sensors and modulators. However, most proposed quasi-BICs in metasurfaces are composed of unit cells with Cs symmetry that may experience performance degradation due to polarization deviation, posing challenges in practical applications. Addressing this critical issue, our research introduces an innovative approach by incorporating metasurfaces with C4v unit cell symmetry to eliminate polarization response sensitivity. Vanadium Dioxide (VO2) is a phase-change material with a relatively low transition temperature and reversibility. Here, we theoretically investigate the polarization-insensitive quasi-BIC modulation in Si-VO2 hybrid metasurfaces. By introducing defects into metasurfaces with Cs, C4, and C4v symmetries, we enable the emergence of quasi-BICs characterized by strong Fano resonance in their transmission spectra. Via numerically calculating the multipole decomposition, distinct dominant multipoles for different quasi-BICs are identified. A comprehensive investigation into the polarization responses of these structures under varying directions of linearly polarized light reveals the superior polarization-independent characteristics of metasurfaces with C4 and C4v symmetries, a feature that ensures the maintenance of maximum resonance peaks irrespective of polarization direction. Utilizing the polarization-insensitive quasi-BIC, we thus designed two different Si-VO2 hybrid metasurfaces with C4v symmetry. Each configuration presents complementary benefits, leveraging the VO2 phase transition's loss change to facilitate efficient modulation. Our quantitative calculation indicates notable achievements in modulation depth, with a maximum relative modulation depth reaching up to 342%. For the first time, our research demonstrates efficient modulation using polarization-insensitive quasi-BICs in designed Si-VO2 hybrid metasurfaces, achieving identical polarization responses for quasi-BIC-based applications. Our work paves the way for designing polarization-independent quasi-BICs in metasurfaces and marks a notable advancement in the field of tunable integrated devices.

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Photonic Bound States in the Continuum in Nanostructures

Cited by 2 publications

References 245 publications

Detection of Low-Concentration Biological Samples Based on a QBIC Terahertz Metamaterial Sensor

Detection of Low-Concentration Biological Samples Based on a QBIC Terahertz Metamaterial Sensor

Efficient polarization-insensitive quasi-BIC modulation by VO₂ thin films

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Photonic Bound States in the Continuum in Nanostructures

Cited by 2 publications

References 245 publications

Detection of Low-Concentration Biological Samples Based on a QBIC Terahertz Metamaterial Sensor

Detection of Low-Concentration Biological Samples Based on a QBIC Terahertz Metamaterial Sensor

Efficient polarization-insensitive quasi-BIC modulation by VO2 thin films

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Efficient polarization-insensitive quasi-BIC modulation by VO₂ thin films