Dual-Channel Photonic Crystal Fiber Sensor Integrating Hyperbolic Mode Resonance and Lossy Mode Resonance for Simultaneous Measurement of RI and Temperature

Abstract

Hyperbolic mode resonance (HMR) has emerged as a solution to conventional sensing limitations. HMR is introduced into a photonic crystal fiber (PCF) for sensing in this research. A dual-channel PCF sensor for both refractive index (RI) and temperature measurement is proposed. The device has two independent sensing channels on the dual-side polishing surface of the PCF. An Au/SnO2 bilayer in the RI channel induces HMR, while the SnO2/PDMS bilayer in the temperature channel induces lossy mode resonance, with PDMS as the temperature-sensitive material. By introducing an Au layer to excite the HMR effect, the sensor achieves enhanced resonance depth and figure of merit (FOM) without sacrificing sensitivity. When the RI ranges from 1.34 to 1.426 and the temperature varies from 25 °C to 100 °C, the optimized sensor achieves a maximum RI sensitivity of 9100 nm/RIU and a maximum temperature sensitivity of −5 nm/°C. A 2×2 sensitivity-matrix analysis confirms effective dual-parameter decoupling, with demodulation errors below 5×10−4 RIU and 0.1 °C under simultaneous RI and temperature variations. This PCF sensor offers high sensitivity, quantifiably low crosstalk, wide detection range and good fabrication tolerance, making it promising for biomedical, environmental and industrial applications.