Investigation of metallic nanowire-based localized surface plasmon resonance optical biosensors using extinction spectra

In this study, we investigate the impact of the cross sectional profile of an array of metallic nanowires on the feasibility of a localized surface plasmons resonance (LSPR) biosensor. Calculations were performed using rigorous coupled wave analysis with an emphasis on the extinction properties of the LSPR structure. It was confirmed that the resonance spectrum strongly depends on the nanowire period and profile. Our numerical results indicate that the nanowire structure, particularly that of a T-profile, delivers extremely linear sensing performance over a wide range of target refractive index with much enhanced sensitivity. The extinction-based LSPR structure also involves relatively large dimension and thus is expected to provide a feasible biosensor using current semiconductor technology.