Reflection based silicon incorporated silver coated fiber optic SPR sensor for refractive index and temperature measurement

We report a reflection based multimode fiber surface plasmon resonance (SPR) sensor utilizing a high index silicon layer between silver metal and sensing medium layer. Theoretical studies have been carried out to optimize the suitable width of material layer to sense refractive index (RI) of the analyte surrounding the optical fiber sensing region using the transfer matrix method. The RI sensitivity of the proposed SPR sensor has been experimentally verified to reach 4774 nm/RIU with figure of merit of 36.07 and resolution of 6.28 × 10⁻⁵at 1.38 RI. Furthermore, the large thermo-optic coefficient and thermal expansion coefficient of the silicon layer has enhanced the experimental temperature sensitivity of the SPR sensor to 1.76 nm/°C.