Forces and transport velocities for a particle in a slot waveguide.

Optofluidic transport seeks to exploit the high-intensity electromagnetic energy in waveguiding structures to manipulate nanoscopic matter using radiation pressure and optical trapping forces. In this paper, we present an analysis of optical trapping and transport of sub-100 nm polystyrene and gold nanoparticles in silicon slot waveguides. This study focuses on the effect of particle size, particle refractive index, and slot waveguide geometry on trapping stability and the resulting transport speed. Our results indicate that stable trapping and transport can be achieved for objects as small as 10 or 20 nm in diameter with as much as a 100 fold enhancement in trapping stiffness over the state of the art.