Terahertz GaAs Indicator Chip Based on High-Q-Factor Spoof Localized Surface Plasmons Resonator

Abstract

Spoof localized surface plasmons (spoof LSPs, SLSPs) have recently emerged as high-quality-factor (Q-factor) multipole electromagnetic resonant structures, showcasing considerable promise in the field of sensing. However, sensing in the terahertz band presents notable challenges. Here, a dual-port coupled SLSPs resonator and a single-port coupled SLSPs resonator are proposed with phase separated excitation, both exhibiting high-Q-factors in the terahertz band. The dual-port coupled SLSPs can sustain both odd resonance mode and even resonance mode, whereas the single-port coupled SLSPs can generate vortex wave resonance modes and asymmetric modes. In the measurement, the highest Q value of the dual-port resonator is 69 at the frequency of 179.4 GHz. Equally noteworthy is the single-port resonator, which reaches a groundbreaking Q-factor of 405.4 at the frequency of 150 GHz, marking a significant advancement in the Q-factors of passive devices. Biosensing for Bletilla, Fritillaria, Rhubarb, and glucose in the terahertz band is implemented, with the maximum frequency shift of 15.8 GHz for the dual-port coupled SLSPs and 7.8 GHz for the single-port coupled SLSPs. The maximum sensing figures of merits (FoM) are 4.1 and 12.9RIU⁻¹ for the dual- and single-port resonators, respectively, underscoring substantial potentials of this work in the realm of terahertz sensing.