Universal terahertz trace molecular fingerprint sensing based on high-degree-of-freedom dielectric metagrating

Abstract

Label-free molecular detection plays a vital role in the terahertz (THz) field but remains limited by weak light–matter interaction and narrow detection bandwidth, especially for trace analytes. Here, we propose a dielectric metasensor that synergistically couples guided mode resonance and quasi-bound states in the continuum to achieve multimodal enhancement. On this basis, three multiplexing strategies—geometric scaling, incident angle modulation, and waveguide thickness adjustment—are implemented to provide broadband adaptability and structural tolerance. Numerical simulations demonstrate that the “angle multiplexing–thickness compensation” hybrid mechanism narrows the scanning range while effectively enhancing both the resolution and the intensity of fingerprint recognition, with a maximum signal enhancement of 10.69 dB. The method offers a promising pathway for the practical application of THz metasensing in high-throughput biosensing, chemical analysis, and environmental monitoring.