SPR Sensor Based on Cascaded NCF and U-Shaped Multimode Fibers for Simultaneous Detection of Refractive Index and Temperature

A surface plasmon resonance (SPR) sensor based on hybrid structure with cascaded no-core fiber (NCF) and U-shaped multimode fiber (MMF) for simultaneous measurement refractive index (RI) and temperature is proposed. One of the SPR channels excited using the U-shaped MMF coated with an Au film is employed for measuring the RI, while the other SPR channel that is excited using the NCF coated with an Au film and polydimethylsiloxane (PDMS) is used for temperature measurement at the same time. The experimental results show that an RI sensitivity of 3364 nm/RIU and a temperature sensitivity of −3.26 nm/°C are achieved by using the proposed sensor. The proposed sensor offers the advantages of a compact structure and stability, making it suitable for potential applications in fields requiring multiparameter measurements, such as environmental monitoring, drug diagnostics, and biochemical sensing.