Quasi-analytical solutions of hybrid platform and the optimization of highly sensitive thin-film sensors for terahertz radiation

TL;DR

This paper develops quasi-analytical solutions for a hybrid metallic and dielectric platform to optimize terahertz sensors, achieving ultrahigh sensitivity through resonance engineering and validating results with simulations.

Contribution

It introduces a novel quasi-analytical approach to design and optimize highly sensitive THz thin-film sensors based on hybrid platforms.

Findings

High-order spoof surface plasmon resonances induced by Wood anomalies.

Achieved ultrahigh figure of merit for thin film sensing.

Designed a perfect absorber with enhanced sensitivity for THz detection.

Abstract

We present quasi-analytical solutions (QANS) of hybrid platform (HP) comprising metallic grating (MG) and stacked-dielectric layers for terahertz (THz) radiation. The QANS are validated by finite difference time domain simulation. It is found that the Wood anomalies induce the high-order spoof surface plasmon resonances in the HP. The QANS are applied to optimize new perfect absorber for THz sensing of large-area thin film with ultrahigh figure of merit reaching fifth order of magnitude for the film thickness 0.0001p (p: MG period). The first-order Wood's anomaly of the insulator layer and the Fabry-Perot in the slit's cavity account for the resonance of the perfect absorber. The QANS and the new perfect absorber may lead to highly sensitive and practical nano-film refractive index sensor for THz radiation.