Terahertz(THz)molecular fingerprint sensing provides a powerful label-free tool for the detection of trace-amount samples.Due to the weak light-matter interaction,various metallic or dielectric metasurfaces have been adopted to enhance fingerprint absorbance signals.However,they suffer from strong background damping or complicated sample coating on patterned surfaces.Here,we propose an inverted dielectric metagrating and en-hance the broadband THz fingerprint detection of trace analytes on a planar sensing surface.Enhancement of the broadband signal originates from the effects of evanescent waves at the planar interface,which are excited by multiplexed quasi-bound states in the continuum(quasi-BICs).One can evenly boost the near-field intensities within the analytes by tuning the asymmetry parameter of quasi-BIC modes.The multiplexing mechanism of broadband detection is demonstrated by manipulating the incident angle of excitation waves and thickness of the waveguide layer.Compared to the conventional approach,the THz fingerprint peak value is dramatically elevated,and the largest peak enhancement time is 330.Our work gives a promising way to facilitate the meta-sensing of the THz fingerprint on a planar surface and will inspire universal THz spectral analysis for trace analytes with different physical states or morphologies.

XUEYING LIU;WEI CHEN;YONGJIE MA;YINONG XIE;JUN ZHOU;LIGUO ZHU;YADONG XU;JINFENg ZHU

Institute of Electromagnetics and Acoustics and Key Laboratory of Electromagnetic Wave Science and Detection Technology,Xiamen University,Xiamen 361005,China;State Key Laboratory of Applied Optics,Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences,Changchun 130033,China;Terahertz Research Center,University of Electronic Science and Technology of China,Chengdu 610054,China;Microsystem and Terahertz Research Center,China Academy of Engineering Physics,Mianyang 621900,China;School of Physical Science and Technology and Institute of Theoretical and Applied Physics,Soochow University,Suzhou 215006,China

光子学研究（英文）

[1]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].光子学研究（英文）,2022(12):2836-2845

metagrating

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