A novel plasmonic refractive index sensor based on gold/silicon complementary grating structure*

A novel complementary grating structure is proposed for plasmonic refractive index sensing due to its strong resonance at near-infrared wavelength. The reflection spectra and the electric field distributions are obtained via the finite-difference time-domain method. Numerical simulation results show that multiple surface plasmon resonance modes can be excited in this novel structure. Subsequently, one of the resonance modes shows appreciable potential in refractive index sensing due to its wide range of action with the environment of the analyte. After optimizing the grating geometric variables of the structure, the designed structure shows the stable sensing performance with a high refractive index sensitivity of 1642 nm per refractive index unit (nm/RIU) and the figure of merit of 409 RIU-1. The promising simulation results indicate that such a sensor has a broad application prospect in biochemistry.

Automated summary

A novel complementary grating structure with strong resonance at near-infrared wavelength is proposed for plasmonic refractive index sensing. Numerical simulation results show that multiple surface plasmon resonance modes can be excited in this structure, with one mode exhibiting significant potential in refractive index sensing. After optimization, the designed structure demonstrates stable sensing performance with a high refractive index sensitivity and figure of merit, suggesting broad application prospects in biochemistry.