Optical forces on Quantum dots in the near field region of resonant metallic nano-structures

We examine the forces on a single quantum dot in the presence of resonantly enhanced electric fields and steep field gradients confined to a sub-wavelength region in the near-field of the structure. To accurately resolve the sub-wavelength geometrical features of this structure, we employ the AMR-FDTD method with local space and time grid refinement using a 3D grid interface interpolation algorithm that preserves the second-order accuracy of the original FDTD scheme and is stable for long time integration. Using AMR-FDTD gives detailed access to the near field structure of the enhanced fields and consequently the gradient forces experienced by the quantum dot (QD) located near the tips.