Refractive index sensitivity enhancement of optical fiber SPR sensor utilizing layer of MWCNT/PtNPs composite

An optical fiber surface plasmon resonance (SPR) sensor with MWCNT/PtNPs sensitive layer is presented. The core of optical fiber with gold film is coated with multilayer carbon nanotubes and platinum nanoparticles composite (MWCNT/PtNPs) by layer-by-layer self-assembled method. Compared with traditional optical fiber SPR sensors with gold film and optical fiber SPR sensors with MWCNT deposited on gold film, the sensitivity and figure of merit (FOM) of the proposed sensor have been greatly improved. The refractive index sensitivity of the optical fiber SPR sensor with gold film, optical fiber SPR sensors with MWCNT deposited on gold film and the proposed sensor are 1863 nm/RIU, 2524 nm/RIU and 5923 nm/RIU respectively, the FOM of the three types of sensors are 13.86, 7.74 and 29.32 respectively. Additionally, the sensor has been optimized for the best performance in terms of composition ratio of the composite. The sensitivity of SPR based optical fiber sensor increases as the proportion of platinum nanoparticles in the composite increases.