Ultrasensitive specific sensor based on all-dielectric metasurfaces in the terahertz range

Abstract

An ultrasensitive specific sensor based on all-dielectric metasurfaces in the terahertz range was proposed. The designed metasurfaces consist of multi pairs of tilted silicon bars on a SiO₂ substrate with a high-Q Fano resonance feature. The peak of this high Q Fano resonance can form a wide reflection spectrum band by scanning the angle of the incident THz waves. Utilizing this angle-scanning strategy, we designed a metasurface sensor and its reflection spectrum band can cover the absorption peak of tyrosine and santonin. By depositing different thicknesses of tyrosine and santonin on the sensor, we have successfully identified them with a detection limit of 6.7 μg cm⁻² and 59.35 μg cm⁻², respectively. The performance of the sensor with high sensitivity has been analyzed in detail, showing an exciting prospect for identification of ‘fingerprint’ spectra in the terahertz region.