Plasmonic Nanopillar Arrays for Optical Trapping, Biosensing, and Spectroscopy

In this work, we propose a unique plasmonic substrate that combine the strength of localized and extended surface plasmons for optical trapping, spectroscopy and biosensing, all in the same platform. The system is based on periodic arrays of gold nanopillars fabricated on a thin gold sheet. The proposed periodic structure exhibits high refractive index sensitivities, as large as 675 nm/RIU which is highly desirable for biosensing applications. The spectrally sharp resonances, we determine a figure of merit, as large as 112.5. The nanopillar array also supports easily accessible high near-field enhancements, as large as 10.000 times, for surface enhanced spectroscopy. The plasmonic hot spots with high intensity enhancement lead to large gradient forces, 350 pN/W/mu m(2), needed for optical trapping applications.