Optical sensing of refractive index (RI) and temperature by dual-channel surface plasmon resonance (SPR) using two single-mode fibers (SMFs) and three multi-mode fibers (MMFs).

A dual-channel surface plasmon resonance (SPR) sensor, based upon a multimode-single mode-multimode-single mode- multimode (MSMSM) fiber structure, is reported for the simultaneous measurement of temperature and refractive index. One channel is coated with an indium tin oxide-silver layer for refractive index sensing, and the channel is coated with Au and cyclohexane layer for temperature sensing. The experiments show that the sensor provides high sensitivity with values of 3379 nm/RIU across the refractive index range from 1.333 to 1.3699 and −3.163 nm/°C from 40 °C to 90 °C. The cross-sensitivity problem is resolved by the dual-wavelength matrix method. Moreover, the proposed sensor has good stability, low cost, and a compact structure and may be employed in biology, chemistry, and environmental testing. [ABSTRACT FROM AUTHOR]