Terahertz Guided Mode Resonance Sensing Platform Based on Freestanding Dielectric Materials: High Q-Factor and Tunable Spectrum

We theoretically investigated a polyethylene-based rectangular and guided mode resonance (GMR) structure with a circular pattern by using the finite-difference time-domain (FDTD) method in the terahertz region. As the refractive index of the grating decreased, the resonance frequency increased, and the Q-factor significantly increased because of the change in the effective refractive index. In addition, GMR was investigated with a sensing layer for sensing applications. The resonance frequency and Q-factor could be perfectly modulated by varying the complex refractive index and thickness of the sensing layer. These results indicate that GMR could be applied to highly sensitive label-free detection, using low-cost GMR sensing platforms based on dielectric materials.