Evolution of Fano resonance based on symmetric/asymmetric plasmonic waveguide system and its application in nanosensor

• We can obtain single double or multiple Fano profiles.
• These Fano prifiles can be easily tuned.
• We can explain the evolution of these Fano profiles by the theoretical analysis.
• All these features can find widely applications in the plasmonic nano-sensing area.

We proposed a plasmonic nanosensor based on Fano resonance in the symmetric and asymmetric plasmonic waveguide system, which comprises with a rectangular cavity and two slot cavities with the metal-dielectric-metal waveguide. Simulation results show that by symmetric/asymmetry rectangular cavity and regulating the rectangular cavity coupling with slot cavities, different waveguide modes can be excited. Due to the interaction of the waveguide mode, the transmission spectra possess single, double or multiple sharp asymmetrical profiles. Because of the different origins, these Fano resonances exhibit different dependence on the parameters of the structure and can be easily tuned. These characteristics offer flexibility to design the device. This nanosensor yields a sensitivity of ∼800 nm/RIU and a figure of merit of about ∼1.35×104, which can find widely applications in the plasmonic nano-sensing area.