Photonics Research, Volume. 10, Issue 12, 2836(2022)

Enhancing THz fingerprint detection on the planar surface of an inverted dielectric metagrating

Xueying Liu1,2, Wei Chen1, Yongjie Ma1, Yinong Xie1, Jun Zhou3, Liguo Zhu4, Yadong Xu5, and Jinfeng Zhu1,2、*
Author Affiliations
  • 1Institute of Electromagnetics and Acoustics and Key Laboratory of Electromagnetic Wave Science and Detection Technology, Xiamen Universityhttps://ror.org/00mcjh785, Xiamen 361005, China
  • 2State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
  • 3Terahertz Research Center, University of Electronic Science and Technology of China, Chengdu 610054, China
  • 4Microsystem and Terahertz Research Center, China Academy of Engineering Physics, Mianyang 621900, China
  • 5School of Physical Science and Technology and Institute of Theoretical and Applied Physics, Soochow University, Suzhou 215006, China
  • show less
    Figures & Tables(0)
    Schematic drawing of THz molecular fingerprint sensing on a planar surface, where the all-dielectric metastructure supports a series of quasi-BICs by using angle-multiplexed signals. The symbols w1, w2, w3, and w4 denote the widths of four grating elements, while p, h1, and h2 represent the unit cell period, grating layer height, and WG layer height, respectively.
    (a) Dispersion relations in the WG layer for the fundamental mode of TM wave and in the air. (b) Reflectance (R) of a bare metastructure as a function of frequency and asymmetry parameter. The inset is the reflectance spectrum of η=0.05 fitted by the Fano equation. (c) Linewidth and Q factor as functions of η. (d) Normalized electric field Ex distributions at corresponding resonance frequencies. (e) Maximum local electric field enhancement at the planar interface. (f) Absorbance of the metastructure with a perturbation analyte layer 1 μm thick, whose refractive index is n˜=1.5+0.05i. All metastructures are under normal incidence with p=260 μm, w1=w3=65 μm, w0=65 μm, h1=50 μm, and h2=150 μm.
    (a) Reflectance of a bare metastructure as a function of frequency and θ. (b) Normalized electric field distributions at resonance frequencies under different θ values. (c) Maximum local electric field enhancement at the planar interface for different θ values. (d) Reflectance before and after introduction of a perturbation analyte layer (n˜=1.5+0.05i) 1 μm thick at the planar interface for different θ values. For all simulations, the metastructure parameters are p=260 μm, η=0.8, w1=w3=65 μm, w2=117 μm, w4=13 μm, h1=50 μm, and h2=150 μm.
    (a) Complex refractive index of α-lactose and its three surface coating cases for equal volumes of trace samples. The angle-multiplexed reflectance spectra and their envelopes are provided for (b) a bare metastructure, (c) case I, (d) case II, and (e) case III, where each inset denotes the normalized electric field distribution for the minimum reflectance peak at θ=46°. (f) Absorbance envelopes of three cases and the sensing enhancement factors versus a reference spectrum for case III. For all simulations, the metastructure parameters are p=260 μm, η=0.8, w1=w3=65 μm, w2=117 μm, w4=13 μm, h1=50 μm, h2=150 μm, and θ changes from 28° to 71°.
    (a) Absorbance spectra of α-lactose with different thicknesses by conventional sensing. (b) Retrieved absorbance signals of 1 μm α-lactose by the angle-multiplexed metasensing method. For the simulation of α-lactose, the metastructure parameters are p=260 μm, w1=w3=65 μm, h1=50 μm, h2=150 μm, and θ changes from 28° to 71°. (c) Real part conductivity of 20 nm thick rGO. (d) Absorbance envelope of 20 nm thick rGO and the broadband enhancement factors versus a reference absorbance spectrum. For the simulation of rGO, the metastructure parameters are p=130 μm, η=0.6, w1=w3=32.5 μm, w2=58.5 μm, w4=6.5 μm, h1=50 μm, h2=150 μm, and θ changes from 22° to 59°.
    (a) Schematic drawing of the THz quasi-BIC all-dielectric metasensor using a thickness-multiplexed sensing scheme. (b) Reflectance as a function of frequency and thickness h2. (c) Field distributions for resonance peaks at a frequency of 2.7 THz. (d) Thickness-multiplexed (tunable h2) reflectance spectra and envelope for an unloaded metasensor. (e) Complex refractive index of histidine. (f) Reflectance spectra and envelope of coating 1 μm thick histidine on the metasensor. The normal incidence of THz waves is applied on the metastructure, whose parameters are p=105 μm, η=0.8, w1=w3=26.25 μm, w2=47.25 μm, w4=5.25 μm, and h1=35 μm.
    (a) Normalized electric field distributions of unloaded metastructures at f=2.7 THz for different values of η. (b) Absorbance signals of histidine and broadband sensing enhancement factors for η=0.6. The device parameters are p=105 μm, w1=w3=26.25 μm, h1=35 μm, and h2 changes from 0 to 200 μm at intervals of 5 μm. (c) Real part of conductivity σ for a 20 nm thick Mo-based MXene film. (d) Absorbance envelopes of MXene and broadband sensing enhancement factors for η=0.6. The device parameters are p=200 μm, w1=w3=50 μm, h1=60 μm, and h2 changes from 0 μm to 350 μm at intervals of 5 μm.
    Simulated reflectance spectra and Fano fitting for (a) η=0.2, (b) η=0.4, (c) η=0.6, and (d) η=0.8.
    (a) Reflectance spectra with different thicknesses h2 and normalized electric field distributions at resonance frequencies under normal incidence. (b) Angle-multiplexed reflectance spectra and envelopes of coating 1 μm thick α-lactose on the metasensor. (c) Absorbance envelopes with different thicknesses h2. For all simulations, the metastructure parameters are p=260 μm, η=0.8, w1=w3=65 μm, w2=117 μm, w4=13 μm, and h1=50 μm.
    (a) Absorbance spectra of α-lactose with different thicknesses by conventional sensing. (b) Retrieved absorbance signals of 1 μm α-lactose by the thickness-multiplexed metasensing method. The normal incidence of THz waves is applied on the metastructure, whose parameters are p=500 μm, w1=w3=125 μm, w2=225 μm, w4=25 μm, h1=128 μm, and h2 changes from 65 to 600 μm at intervals of 5 μm.
    (a) Angle-multiplexed reflectance spectra and envelope R0 for an unloaded lossy metasensor. (b) Angle-multiplexed reflectance spectra and envelope of coating 1 μm thick α-lactose on the metasensor. (c) Absorbance signals and broadband sensing enhancement factors. The metastructure parameters are p=260 μm, η=0.8, w1=w3=65 μm, w2=117 μm, w4=13 μm, h1=50 μm, h2=150 μm, and θ changes from 28° to 70°. (d) Thickness-multiplexed reflectance spectra and envelope R0 for an unloaded lossy metasensor. (e) Thickness-multiplexed reflectance spectra and envelope of coating 1 μm thick α-lactose on the metasensor. (f) Absorbance signals and broadband sensing enhancement factors. The normal incidence of THz wave is applied on the metastructure, whose parameters are p=500 μm, η=0.8, w1=w3=125 μm, w2=225 μm, w4=25 μm, h1=128 μm, and h2 changes from 65 to 600 μm at intervals of 5 μm.
    • Table 1. Fingerprint Detection Performance of Dielectric Metasensors

      View table
      View in Article

      Table 1. Fingerprint Detection Performance of Dielectric Metasensors

      ReferenceMetastructureSensing SurfaceAnalyteMultiplexed SchemeSpectral RangePeak Enhancement Times
      [15]Pair pillarsPatternedProtein A/GGeometryMid-IR60
      [16]Pair pillarsPatternedPMMAAngleMid-IR50
      [40]MetagratingPatternedhBNAngleMid-IR34
      [5]MetagratingPatternedα-lactoseAngleTHz13
      Our workInverted metagratingPlanarα-lactoseGeometry/angleTHz308/330
    Tools

    Get Citation

    Copy Citation Text

    Xueying Liu, Wei Chen, Yongjie Ma, Yinong Xie, Jun Zhou, Liguo Zhu, Yadong Xu, Jinfeng Zhu. Enhancing THz fingerprint detection on the planar surface of an inverted dielectric metagrating[J]. Photonics Research, 2022, 10(12): 2836

    Download Citation

    EndNote(RIS)BibTexPlain Text
    Save article for my favorites
    Paper Information

    Category: Optical Devices

    Received: Aug. 4, 2022

    Accepted: Oct. 18, 2022

    Published Online: Nov. 24, 2022

    The Author Email: Jinfeng Zhu (nanoantenna@hotmail.com)

    DOI:10.1364/PRJ.472114

    Topics

    Please enter the answer below before you can view the full text.
    4-2=
    Submit