Sensitivity enhancement of THz metamaterial by reduction of the Fabry-Pérot oscillations and decoupling its resonance from substrate losses

We demonstrate an optical method for sensitivity enhancement for LC resonant MM’s, using meta-plate which act as plasmonic enhancer by increasing the electric field concentration in the active area of the metasurface. This makes the MM resonance ultra-sensitive to the tiny changes of particle size/concentration under test spread on the metasurface, contributing to enhanced spectral shift (ΔF). The meta-plate also makes the Si substrate optically lossless and transparent in THz, enabling the full effect of MM resonance without any substrate losses in the transmission spectra. This work also demonstrates an extended concept of de-coupling MM-resonance from the substrate’s Fabry-Pérot (FP) oscillations by de-trapping of the THz radiation from the MM substrate, resulting in the improved quality-factor of the MM resonance and overall plasmonic enhancement on the metasurface. The plasmonic enhancer meta-plate increases the ΔF by eight-fold compared to MM’s fabricated on conventional Si substrates.