Compact Three-Channel Photonic Crystal Fiber Sensor Based on Surface Plasmon Resonance

In order to improve the integration of fiber optic sensors, this paper designs a dual-core three-channel photonic crystal fiber (PCF) optic sensor that can simultaneously measure the refractive index of a liquid, its temperature, and the ambient magnetic field. Based on the PCF as well as SPR principles, the sensor has two D-planes, one coated with PDMS as well as a gold film for detecting temperature and the other coated with a gold film for detecting refractive index and coated with a gold film over the air holes on the side of the core where the refractive index is measured and a magnetic fluid injected into the air holes to detect the magnetic field. The results show a maximum sensitivity of 20,000 nm/RIU for refractive index, a linear sensitivity of 116 pm/Oe for magnetic field, and 5300 pm/°C for temperature when the sample’s refractive index is between 1.36 and 1.42, the temperature is between 0 °C and 50 °C, and the magnetic field is between 20 and 550 Oe. The sensitivity matrix of temperature versus refractive index is also given. The sensor is compact and simple to prepare, providing a new solution for miniaturization and integration of multifunctional photonic devices.