Cross-sensitivity immune SPR sensor based on fan-shaped microstructured optical fiber for temperature and refractive index sensing.

To avoid coating and filling into the fiber holes, facilitate the phase-matching and eliminate cross-sensitivity problems, we propose a surface plasmon resonance sensor based on a fan-shaped microstructured optical fiber (MOF) for the simultaneous sensing of temperature and refractive index (RI). The fan-shaped structure is fabricated by polishing two sides of MOF with an angle of 120°. One side is coated with the gold film and polydimethylsiloxane layer for temperature sensing, and the other side is only coated with the gold film for RI sensing. The two sensing sides can support resonance peaks with two polarized directions at the angle of 120°, which are independent without cross-sensitivity. By monitoring the shifts of the two polarized peaks, our numerical results show that the temperature sensitivity is 2.932 nm/°C in the range of 30 °C to 40 °C, and RI sensitivity is 4235 nm/RIU in the range of 1.38 to 1.39, respectively.