Ultra‐Broadband, Rapid, and Trace Terahertz Fingerprint Detection via Resonance Interaction Enhancement with an Unpatterned Dielectric Wafer

Abstract Enhancing the interaction between light and matter, especially at the terahertz band, is pivotal for achieving ultra‐broadband trace molecular fingerprint detection. Here, an efficient scheme featuring multiple Fabry–Pérot modes with equal intervals and uniform intensity is presented to implement a resonance interaction enhancement of molecular fingerprints with long‐awaited precision and flexibility. This technique constructs uniform resonant probes across the entire spectral range to reveal molecular coupling effects via frequency‐selective amplitude attenuation, enabling both qualitative and quantitative detection of L‐tyrosine with a detection limit of 0.11 µg mm −2 . This is an inaugural experimental achievement of quantitative THz trace fingerprint detection with dual capabilities of achieving ultra‐broadband and high‐efficiency. Significantly, the technology enables direct identification of molecular absorption signatures from the transmitted multiple Fabry–Pérot modes using wavelet denoising algorithms, eliminating cumbersome data postprocessing and redundant testing procedures. This advancement heralds a new, accessible era in terahertz fingerprint spectroscopy.