Dual-Parameter Hollow-Core Anti-Resonant Fiber (HC-ARF) Based on Terahertz Surface Plasmon Resonance (THz-SPR) for Low Refractive Index and Temperature Change Detection

We present a two-parameter anti-resonant fiber (ARF) optic sensor based on terahertz surface plasmon resonance (THz-SPR) for the simultaneous detection of low refractive index (RI) and temperature. A graphene layer is selectively coated on the negative curvature tube wall to excite the THz surface plasmon polarization (SPP) mode for detecting low RI analytes. The response to temperature changes is accomplished through dimethylsiloxane (PDMS) filled in graphene-coated tubes. Finite element method (FEM) analysis showed that the sensing characteristics of the first resonance peak were better than the second resonance peak when the RI was in the range of 1.26–1.33, and the maximum wavelength sensitivity and resolution of the first resonance peak were 16142.05[Formula: see text][Formula: see text]m/RIU and [Formula: see text][Formula: see text]RIU[Formula: see text], respectively, with the maximum FOM reaching 207.18[Formula: see text]RIU[Formula: see text]. The first resonance peak is sensitive to temperature when the temperature varies between 6[Formula: see text]C and 76[Formula: see text]C, and the maximum wavelength sensitivity occurs at the second resonance peak of 3.81[Formula: see text][Formula: see text]m/[Formula: see text]C, all with a resolution up to 10[Formula: see text] orders of magnitude. The proposed ARF-SPR sensor is capable of realizing two-parameter measurements in the THz band, and this study focuses on the detection of low RI neighborhoods, which is rarely mentioned in the application scope of THz-SPR sensors. This study reveals the superior ability of our sensors to detect 10[Formula: see text] scale minimum RI changes in solutions of aerogels, halogenated ethers and fluorinated organics, which greatly expands the application of existing THz-SPR sensors for drug testing and drug leakage monitoring.