Optical trapping using double negative index fishnet metamaterial

We calculate the optical force exerted on the nanoparticle close proximity to the surface of fishnet metamaterials penetrating through metal/dielectric/metal films when irradiated at near infrared wavelength. These forces show the resonant frequencies similar to the magnetic resonant frequencies in the double negative index fishnet metamaterial. We also present that the optical force can be enhanced by optimizing the geometry of the fishnet to provide a stronger magnetic resonant dipole. In contrast to the other plasmonic nanostructure always obtaining trapping force using electrical resonant dipole, our presented structure utilizes the magnetic resonance to provide a gradient force, which is suitable for the optical trapping of the nanoscale particles at illumination intensities of just 1mW/mu m(2), the optical force is sufficient to overcome the Earth's gravitational pull.