Dual-frequency and dual-polarization multiplexed terahertz biochemical sensor based on chiral metasurface

Metasurfaces offer a novel platform for terahertz spectroscopic detection of chiral biochemical substances. However, multichannel and high-sensitivity metasensors still require further development. This paper presents a dual-frequency, dual-polarization multiplexed terahertz metasensor based on metallic chiral resonators. It utilizes orthogonally linearly polarized terahertz waves at two distinct frequencies as independent sensing channels. Using L-proline as an example, we designed and fabricated a sensor prototype and evaluated its sensing performance for different linear polarizations near 0.6 and 0.9 THz. Frequency shift sensitivities of 3.75 GHz/(μg/cm2) and 4.27 GHz/(μg/cm2) were achieved in the two working modes, respectively. Additionally, we demonstrated the polarization ellipse of the transmitted wave as an intuitive sensing indicator. Both the ellipticity and azimuth angle showed significant changes with increasing analyte concentration. The consistent trends observed in both simulations and experiments fully validate the feasibility of the proposed approach. The findings of this study provide new insights for the development of novel multichannel, high-sensitivity metasensors.