Terahertz asymmetric metallic hole arrays with polarization-independent quasi-bound states in the continuum for membrane sensing

Liu, De Jun; Xi, Yu; Wu, Feng; Du, Weijie; Chen, Lin; Liu, Feng; Kuwahara, Makoto; Ono, Shingo

doi:10.1364/oe.494306

Cited by 14 publications

(12 citation statements)

References 57 publications

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“…Sharp quasi-BICs are sensitive to changes in materials such as absorption and refractive index [ 14 , 23 , 25 , 35 ]. In full metal-based metasurfaces, high conductivities show higher Q-factors [ 14 , 23 , 25 ].…”

Section: Simulation Results and Analysismentioning

confidence: 99%

“…A sensitivity of 151 GHz/RIU for 50-μm polymer was obtained, higher than bulky dielectric substrate metamaterials. To further improve the sensitivity of quasi-BICs sensors, a metasurface based on four-hole arrays was proposed, which realizes a polarization-independent quasi-BIC and a high Q-factor exceeding 2000 after optimization [ 25 ]. For a 25 µm-thick polyimide membrane, the measured results exhibit that the frequency shift is 97.5 GHz.…”

Section: Introductionmentioning

confidence: 99%

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Double-Strip Array-Based Metasurfaces with BICs for Terahertz Thin Membrane Detection

Shen,

Wang,

Sheng

et al. 2023

Micromachines

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A double-strip array-based metasurface that supports the sharp quasi-bound states in the continuum (quasi-BICs) is demonstrated in terahertz regions. By tuning the structural parameters of metal strips, the conversion of BICs and quasi-BICs is controllable. The simulated results exhibit an achieved maximum Q-factor for quasi-BICs that exceeds 500, corresponding to a bandwidth that is less than 1 GHz. The optical response of quasi-BICs is mainly affected by the properties of substrates. Resonant frequencies decrease linearly with increasing refractive index. The bandwidth of quasi-BICs decreases to 0.9 GHz when n is 2.2. The sharp quasi-BICs are also sensitive to changes in material absorption. Low-loss materials show higher Q-factors. Thus, the selection of a suitable substrate material will be beneficial in achieving resonance with a high Q value. The sensitivity of DSAs for molecules is assessed using a thin membrane layer. The DSAs show high sensitivity, which achieves a frequency shift of 70 GHz when the thickness of the membrane is 10 μm, corresponding to a sensitivity of 87.5 GHz/RIU. This metasurface with sharp quasi-BICs is expected to perform well in THz sensing.

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Section: Simulation Results and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Double-Strip Array-Based Metasurfaces with BICs for Terahertz Thin Membrane Detection

Shen,

Wang,

Sheng

et al. 2023

Micromachines

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“…Such quasi-BICs possessing polarization-insensitive properties originate from guided mode resonances in metasurfaces via symmetry-breaking. Meal-dielectric or all-metal metasurfaces are also proposed for BICs manipulations although the Ohmic loss is not negligible [22,32,[42][43][44][45][46][47][48][49][50][51]. Kyaw et al reported an asymmetric split-ring resonator-based metasurfaces, realizing polarization-dependence of accidental BICs [32].…”

Section: Introductionmentioning

confidence: 99%

“…The accidental BIC originates from the coupling between plasmonic dipole and higher-order quadrupole modes, which is not obviously affected by the polarization angles. All-metal metasurfaces have stable optical performance after sensing various molecules [22,[46][47][48]52]. Wang et al proposed an H-shaped based all-metal metasurface, whose induced quasi-BICs are sensitive to the ultrathin graphene film [22].…”

Section: Introductionmentioning

confidence: 99%

“…The H-shaped structure selects the polarization waves in which only TE waves are able to excite quasi-BICs. For this purpose, in 2023, asymmetric metal hole arrays have been proposed for polarization-independent quasi-BICs [48]. Experimental results demonstrated that the asymmetric patterns based on hole arrays achieve a high sensitivity of 147.7 GHz/RIU for 25 μm thick PI membrane.…”

Section: Introductionmentioning

confidence: 99%

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Polarization-insensitive quasi-bound states in the continuum supported by terahertz all-metallic complementary periodic cross-shaped resonators

Liu,

Zhang,

et al. 2024

Phys. Scr.

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A strategy to design polarization-insensitive quasi-bound states in the continuum (BICs) metasurfaces based on symmetry-broken metamolecules is introduced. Such metasurfaces consist of four complementary periodic cross-shaped resonators (CPCRs), forming a novel C4 structure through rotating arrangements, whose resonant qualities can be improved by optimizing the slit length. Unlike single CPCRs sensitive to polarization changes, experimental results demonstrate that the constructed metasurface exhibits the same spectral response when the polarization angle alters, despite a 2.4 GHz frequency variation found in these simulated resonances. This polarization-insensitive quasi-BIC show a frequency shift of 67.1 GHz when a 20 μm-thick polyimide membrane is attached. Modification of the structural parameters also has an impact on its sensing performance. The study provides a way to achieve high-quality resonances with polarization-insensitive properties that can be easily applied to high-sensitivity sensor design for THz sensing.

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Terahertz Sensing Based on Floating Bilayer Metasurface with Toroidal Dipole Resonance Toward Ultra‐High Sensitivity

Liu,

Xiao,

Qin

2024

Advanced Optical Materials

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Metasurface structures have proven to be effective in enhancing terahertz sensing signals and can thus be used as sensors to improve terahertz detection sensitivity. However, the sensitivity is limited by the poor spatial overlap between the analytes and the local electric field of the metasurface. In this work, a novel design of a floating bilayer metasurface structure for terahertz sensing is proposed and investigated. This structure supports a sharp toroidal dipole resonance and can concentrate near‐field energy on the analyte and metal atoms rather than on the substrate surface by floating the metal atoms. Consequently, the sensitivity is significantly improved to as high as 362 GHz RIU−1; theoretically, this is approximately 2.6 times higher than that of the common metasurface. The ability of the floating bilayer metasurface to quantitatively detect chlorothalonil is experimentally demonstrated. The resonance peak shows a significant frequency shift of 7 GHz for a change of 0.0001 mg dL−1 in chlorothalonil concentration, reaching up to 86 GHz when the change in chlorothalonil concentration is 100 mg dL−1; this is approximately 6.6 times higher than that of the common metasurface. This work provides opportunities for metasurface to realize ultrasensitive sensing in the terahertz regime.

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Terahertz asymmetric metallic hole arrays with polarization-independent quasi-bound states in the continuum for membrane sensing

Cited by 14 publications

References 57 publications

Double-Strip Array-Based Metasurfaces with BICs for Terahertz Thin Membrane Detection

Double-Strip Array-Based Metasurfaces with BICs for Terahertz Thin Membrane Detection

Polarization-insensitive quasi-bound states in the continuum supported by terahertz all-metallic complementary periodic cross-shaped resonators

Terahertz Sensing Based on Floating Bilayer Metasurface with Toroidal Dipole Resonance Toward Ultra‐High Sensitivity

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