High-Performance coupled plasmon waveguide resonance optical sensor based on SiO2:Ag film

•An optical sensor—a BK7 prism/Ag/SiO2/SiO2:Ag structure—was designed and fabricated.•The device couples localised surface plasmon resonance of Ag nanoparticle in SiO2:Ag film.•The fabricated sensor exhibited enhanced sensitivity and figure of merit values.•The reflectivity spectra could be tuned by manipulating SiO2 interlayer thickness.•The reflectivity spectra could be tuned by manipulating Ag content in SiO2:Ag film. A coupled plasmon waveguide resonance (CPWR)-based optical sensor takes advantage of the evanescent wave at a waveguide boundary to excite surface plasmon polaritons, which can link waveguide electromagnetic energy to a surface plasmon wave to enhance the propagating surface plasmon resonance. Herein, a novel optical sensor having a BK7 prism/Ag/SiO2/SiO2:Ag structure and that couples the localised surface plasmon resonance of Ag nanoparticles in a SiO2 film was designed and fabricated. The results showed that the proposed sensor exhibited higher sensitivity (~1396.85 nm RIU−1) and figure of merit (~11.36 RIU−1) values than a traditional CPWR optical sensor (i.e., 368.50 nm RIU−1 and 1.72 RIU−1, respectively). Moreover, the resonance wavelength could be tuned to the near-infrared region by adjusting the thickness of the SiO2 interlayer or the Ag content of the top SiO2 layer. Simulations and experimental data confirmed that the CPWR-based sensor exhibited superior optical sensing performance.