Simultaneous measurement of temperature and magnetic field based on surface plasmon resonance and Sagnac interference in a D-shaped photonic crystal fiber

A novel D-shaped photonic crystal fiber (PCF) sensor based on surface plasmon resonance (SPR) and Sagnac interference technology is proposed to realize the simultaneous measurement of temperature and magnetic field. Two ultra-large air-holes are introduced into the cladding layer to increase the birefringence. Magnetic fluid (MF) material is filled into the cladding air-holes to measure the temperature and magnetic field based on the dependence of the MF refractive index (RI) on temperature and magnetic field. The D-shaped flat surface coated with a gold layer is in direct contact with ethanol to achieve the dual-parameter demodulation and solve the cross-sensitivity problem. The proposed sensor has the advantages of high sensitivity and easy fabrication for the multi-parameter measurement applications.