Enhanced trace amount terahertz fingerprint spectroscopy using symmetrical spoof surface plasmon metasurfaces

Since the frequency range accords with the fingerprint characteristics of many biomacromolecular materials, terahertz (THz) waves are widely used in the detection of biomacromolecular materials. However, when it is used for real application, how to measure the spectral of trace-amount analysis samples is a major challenge. By localizing electromagnetic fields in dielectric meta-grating or metasurfaces is the most popular way to enhance the spectral signal. In this paper, we propose a design of THz structure that excites a series of spoof surface plasmon (SSP) sharp resonances on the geometry multiplexing metals metasurfaces in one layer to enhance the terahertz absorption spectrum of biomacromolecular materials. The structure can be manufactured and measured easily. The enhanced absorption spectrum can be built by linking a series of SSP sharp resonances. Numerical results show that the absorption enhancement factor about 160 times for the 0.2µm lactose film sample in the frequency range of 0.45–0.61 THz. This design will provide a better method for the detection of biomacromolecular materials.