Ag nanoparticles locally enhanced high performance coupled plasmon waveguide resonance biosensor

Abstract

Coupled plasmon-waveguide resonance (CPWR) biosensor uses the evanescent wave at the waveguide boundary to excite surface plasmon wave (SPW), which couples the energy of the optical field in the waveguide to surface plasmon wave to produce surface plasmon resonance (SPR). In this paper, BK7 prism was combined with Ag/SiO2 structure, Ag nanoparticles were embedded on the surface of SiO2 waveguide layer to form a new CPWR biosensor. Ag nanoparticles can produced light-induced located surface plasmon resonance(LSPR). Resonance coupling between LSPR and CPWR can enhanced the penetration depth and figure of merit (FOM) of traditional biosensors. The finite-difference timedomain (FDTD) method was used to simulate the enhancement behavior of Ag nanoparticles, and to explore the influence of Ag nanoparticles density on the sensor performance. It was found that the penetration depth of the Ag nanoparticle enhanced CPWR biosensor was 1.75 times of that of the traditional CPWR biosensor, and the highest figure of merit was 1.8 times of that of the latter.