Terahertz chiral biochemical metasensor based on analysis of linearly polarized waves

The long-term development of terahertz (THz) metasurface biochemical sensing technology has been constrained by cumbersome operations and poor reproducibility, creating an urgent need for detection schemes that combine high sensitivity, simplified optical paths, and low sample consumption. In this paper, we proposes a chiral metasensor based on double split-ring resonators (DSRRs), which operates using only linearly polarized THz waves. Through ingenious design of the resonator ring radius, the sensor's operational bandwidth can be extended to a broader spectral region. The resonant wavelength exhibits a linear relationship with the ring radius, with a tuning rate of 4.92 GHz/µm. This resonator encodes chiral information at once into the triple responses of frequency shift, transmission intensity, and polarization ellipticity rotation. We experimentally validated an example operating near 0.6 THz, achieving a minimal sample load of only 3.43 µg. At polarization angles of 0° and ±45°, all three optical indicators show a linear relationship with the concentration of proline, with sensitivities reaching 4.53 GHz/(µg/cm²) (frequency shift), 0.0192 /(µg/cm²) (amplitude change), and 4.61 °/(µg/cm²) (azimuth rotation), enabling direct reading of analyte concentration with simple operation. This scheme avoids the complexity of full polarization spectroscopy, offering a highly sensitive, low-cost technical pathway for convenient screening of chiral biomolecules and pharmaceutical analysis in the THz band.