High-Performance Coupled Plasmon Waveguide Resonance Optical Sensor Based On 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 (similar to 1396.85 nm RIU-1) and figure of merit (similar to 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.