Flexible nanoparticle-on-mirror strategy for ultrasensitive molecule detection by directionally coupling surface plasmon polaritons

Applying local surface plasmon resonance (LSPR) to a nanoparticle-on-mirror (NPOM) configuration for realizing highly sensitive molecule detection using surface-enhanced Raman scattering (SERS) typically enhances the Raman signal by 106-1010 under limiting conditions. We propose a special nanoparticle-fishbone structure (NPFS) system, which incorporates the surface plasmon polariton (SPP) coupler of the fishbone structure into the NPOM configuration, to achieve ultra-high local electric field enhancement by plasmon hybridizing the LSPR mode of metallic nanoparticles and the SPP mode of the fishbone array structure. During the numerical simulation, the NPFS system exhibited a SERS enhancement factor of 1011, which is two orders of magnitude higher than that of the NPOM system; the SERS experimental results further demonstrated its outstanding performance. These findings indicate that introducing a well-designed SPP coupler on the metallic film can further improve the advantages of various NPOM configurations. The proposed approach can open new horizons for designing nanoscale photonic devices for ultrasensitive molecule detection.

Automated summary

The study introduces a new nanoparticle-fishbone structure system, which achieves ultra-high local electric field enhancement by incorporating the SPP coupler of the fishbone structure, resulting in a SERS enhancement factor of 1011. Experimental results demonstrate the outstanding performance of this system, providing new insights for designing highly sensitive molecule detection devices.