Modeling of optical trapping using double negative index fishnet metamaterials

Abstract

We calculate the optical forces exerted on nanoparticles in close proximity to the surface of fishnet metamaterials based on metal/dielectric/metal films when irradiated at near infrared wavelength. These forces show resonant frequencies similar to the magnetic resonant frequencies in the double negative index fishnet metamaterial. We also show that the optical force can be enhanced by optimizing the geometry of the fishnet to provide a stronger magnetic resonant dipole. In contrast to most other plasmonic nanostructure which always obtaining trapping force using an electrical resonant dipole, our presented structure utilizes the magnetic resonance to provide a trapping force. We have found that it is suitable for optical trapping of nanoscale particles at illumination intensities of just 1 mW/μm2 and the force is sufficient to overcome gravity.