We propose a novel way to trap and manipulate nano-objects above a dielectric substrate using an apertureless near-field probe. A combination of evanescent illumination and light scattering at the probe apex is used to shape the optical field into a localized, three-dimensional optical trap. We use the coupled-dipole method and the Maxwell stress tensor to provide a self-consistent description of the optical force, including retardation and the influence of the substrate. We show that small objects can be selectively captured and manipulated under realistic conditions.

• Received 10 July 2001

DOI:https://doi.org/10.1103/PhysRevLett.88.123601