Novel optical fiber SPR temperature sensor based on MMF-PCF-MMF structure and gold-PDMS film

In this paper, a novel optical fiber temperature sensor based on surface plasmon resonance (SPR) is presented. The sensor consists of multimode fiber-photonic crystal fiber-multimode fiber (MMF-PCF-MMF) structure coated with gold film, whose refractive index (RI) sensitivity was found to range from 1060.78 nm/RIU to 4613.73 nm/RIU in the RI range of 1.3330-1.3904. Through simulation and experimental results, the RI sensitivity of the MMF-PCF-MMF structure is found to be higher than that of multimode fiber-single mode fiber-multimode fiber (MMF-SMF-MMF) structure. The sensing area was coated with polydimethylsiloxane (PDMS) that has a high thermal coefficient, obtaining a high temperature sensitivity of -1.551 nm/°C in the temperature range of 35-100 °C, which means it has a broad application prospect in medical, environmental monitoring and manufacturing industry.