Surface plasmon resonance refractive sensor based on silver-coated side-polished fiber

We demonstrate a surface plasmon resonance refractive sensor based on the side-polished single mode optical fiber and investigated the sensor performance decay induced by silver coating degradation. The sensor showed fast response to the refractive index liquid in the range from 1.32 to 1.40 RIU. The highest sensitivity up to 4365.5 nm/RIU and a FOM of 51.61 RIU−1 were achieved, which were comparable to the reported polished-fiber-based SPR sensors. Characteristics of the silver-coated sensor after exposure to the air as well as to the liquid environment were investigated. The sensor always stored in dry air could respond stably two weeks later with sensitivity comparable with the fresh one and lower resolution due to the broadened resonant dip. But the sensor immersed in the refractive liquid for 30 min firstly and then exposed to ambient air for hours decayed dramatically due to silver degradation. The presented silver-coated SPR sensor could be used as a simple, cost-effective, disposable device in bio-chemical, environment, and food safety detection.