Research on Integrated Detection and Optimization of Photonic Crystal Fiber Sensors Based on Orthogonal Polarization Mode Separation

A multichannel surface plasmon resonance (SPR) fiber sensor based on orthogonal polarization modes is proposed, featuring a photonic crystal fiber (PCF) structure formed through three-sided polishing and surface grooving, with a regular air-hole arrangement. Channel 1 (Ch1) and Channel 2 (Ch2) are filled with magnetic fluid (MF) and the temperature-sensitive material polydimethylsiloxane (PDMS), respectively, and both channels are coated with a gold film. Under Y-polarized light, Ch1 enables independent detection of magnetic field and temperature, achieving maximum sensitivities of 4.66 nm/Oe and −3.5 nm/°C, respectively. Under orthogonal X-polarization, Ch2 performs temperature sensing with no crosstalk, reaching a peak sensitivity of −5 nm/°C. To enable refractive index (RI) detection, silver is introduced as the plasmonic material in Channel 3 (Ch3). Due to the dispersion differences between silver and gold, two SPR absorption peaks appear in the Y-polarized transmission spectrum, of which only the first peak is sensitive to RI variations. Ch3 supports an RI detection range of 1.26–1.43, with a maximum sensitivity of 28000 nm/RIU. Simulation results confirm that the proposed PCF-SPR sensor exhibits high sensitivity across all three parameters—magnetic field, temperature, and RI—while maintaining broad detection ranges and excellent anti-interference performance. Owing to its versatile capabilities, the sensor holds great promise for applications in biomedicine, food safety, marine environmental monitoring, aerospace, and chemical analysis.