Surface plasmon resonance optical fiber sensor for relative humidity detection without temperature crosstalk

A new method to overcome temperature crosstalk in humidity detection is proposed in this manuscript, which is realized by integrated surface plasmon resonance (SPR) and Mach-Zehnder (MZ) interference in the same optical fiber detection structure. The proposed sensor is made by photonic crystal fiber and multimode fiber, SPR excited by half coated gold film on one side of photonic crystal fiber, MZ interference is made by photonic crystal fiber without gold film coating and multimode fiber. Graphene quantum dots and polyvinyl alcohol (GQDs-PVA) are adopted as relative humidity sensitive materials. By data demodulation, the sensitivity of proposed sensor to relative humidity is 23 pm/%RH. Compared with other RH sensors, the proposed sensor in this manuscript is high integrated, and overcomes the problems of complex data demodulation, which provides a novel idea for the sensor to overcome crosstalk of other factors.