Highly enhanced trace amount terahertz fingerprint spectroscopy by multiplexing surface spoof plasmon metasurfaces in a single layer

Abstract

Terahertz (THz) absorption spectroscopy has a large potential for molecular label-free fingerprinting. But it should overcome barriers to effectively measure the spectra of trace-amount analysis in a real application. The popular solution is enhancing the broadband spectral signals by localizing electromagnetic fields in dielectric metagrating or metasurfaces. In this paper, we numerically demonstrate a sensing scheme based on the geometry multiplexing of metal metasurfaces in one layer steel sheet with a series of spoof surface plasmon (SSP) sharp resonances. The SSP resonances are excited by normal THz incidents. The meta device is easy to manufacture and measure. The linked resonances peaks build an enhanced absorption spectrum. The envelope curve shows a substantial absorption enhancement factor of about 104 times for the 0.1μm lactose film sample in 0.46∼0.60 THz. The proposed method offers a flexible way for the wide terahertz spectra enhancement in trace-amount chemical, organic, or biomedical materials detection.