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

Abstract

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.

Keywords

• Coupled plasmon waveguide resonance
• BK7 prism
• Ag
• SiO2
• SiO2:Ag structure
• Localised surface plasmon resonance