Polarization-Independent Multi-Resonance With High Q-Factor for Highly Sensitive Terahertz Sensors Based on All-Dielectric Metasurface

Since the fingerprints of numerous crucial biologic materials can be identified by terahertz (THz) spectroscopy, THz sensing have become an important approach of biological and medical detections. Particularly, benefit from the excellent capability of metasurface, strong interactions between the metasurface and THz waves can be realized, thus the THz sensing with high sensitivity becomes reality. However, the common configuration of metasurface-based THz sensor is composed of metallic subwavelength structure. Due to the inherent resistive loss of metal, it is still a great challenge to further enhance the quality factor (Q-factor) of resonance and sensitivity of THz sensor. In this work, we designed an all-dielectric metasurface with high Q-factor for highly sensitive THz sensors. The metasurface is a windmill-like structure consisting of four cuboids, and every adjacent two cuboids are arranged alternately vertically and horizontally. The transmission spectrum of metasurface exhibits four polarization-independent and strong resonance peaks with high Q-factor in 0.1-2.5 THz, and all of them show high sensitivity related to ambient refractive index. The transmitted structure and polarization-independent resonances can relief the difficulty of measurement. We believe these studies will lay the theoretical and technical foundation for the design of high-sensitivity terahertz sensing.