Dual D-Shaped Photonic Crystal Fiber Sensor for Three-Parameter Sensing Based on Surface Plasmon Resonance

A surface plasmon resonance (SPR) sensor based on dual D-shaped hollow microstructured fiber is proposed. The sensor consists of rectangular arranged air holes, a gold (Au) thin film, a silver (Ag) thin film, and an indium tin oxide (ITO) thin film. The dual D-shaped structure of the proposed sensor detects three channels simultaneously. The effects of various structural parameters (e.g., sizes of air holes and metallic film thickness) on the sensor performances are investigated with the finite-element method. The maximum wavelength sensitivity (WS) of 47 500 nm/refractive index unit (RIU) in the refractive index (RI) range of 1.39–1.423 in Ch-1 is achieved, corresponding to a resolution of ${2.11} \times {10}^{-{6}} \text {RIU}^{-1}$ . The range of the SPR sensor in Ch-2 is 1.30–1.38, with a maximum WS of 8300 nm/RIU. In Ch-3, the maximum WS is 12.7 nm/°C, ranging from 0°C to 90°C. The proposed SPR RI sensor is sensitive, which can be potentially used for RI and temperature sensing.