Q-ing Up Better THz Sensors: guided-mode resonances in thin-film metagratings

Detecting trace amounts of molecules—from explosives to biomarkers—requires highly sensitive sensors. Many molecules exhibit characteristic vibrational and rotational modes in the THz range, providing molecular fingerprints for label-free spectroscopic detection. However, the weak interaction between freely propagating THz waves and dilute analytes has long limited detection sensitivity.

In the latest publication from our group, Joshua Mornhinweg and colleagues demonstrate a high-performance resonant THz sensor that combines a metallic metasurface with a guided-mode resonance. By using an ultrathin film as the guiding medium, the metagrating platform mitigates the typical THz losses while enhancing the interaction with the analyte. The sensor achieves a record experimental figure of merit, along with high sensitivity, establishing a cost-effective and manufacturing-tolerant platform well suited for demanding trace-detection applications.

See the publication in Optica.

 Artistic rendering by Joshua Mornhinweg.