Refractive Index and Temperature Sensing System With High Sensitivity and Large Measurement Range Using an Optical Fiber

In this article, a temperature and refractive index sensing probe based on a photonic crystal fiber (PCF) with a silver film coating is proposed. We suggested a simple method for coating silver films, and a silver film was coated on the periphery of the PCF that solves the previous difficulties of coating metal film inside the air holes or polishing a flat surface. The sensing probe has achieved dual-parameter sensing of refractive index and temperature by employing polydimethylsiloxane (PDMS) as the temperature-sensitive material. The results of the experiment demonstrated that the wide measurement range and high sensitivity of the sensing probe. It has a refractive index sensitivity of 3341.65 nm/unit of refractive index (RIU) in the range of 1.333–1.3953 and a temperature sensitivity of 2.02 nm/°C in the range of
$50-100\,\,^{\circ }\text{C}$
. The features of the suggested sensing probe, including its simple structure and ease of production, indicate the potential application in the field of biochemical sensing.