Modification of the surface plasmon enhanced optical forces on metal nanorod pairs by axial rotation and by dielectric intralayer

We investigate numerically the effect of axial rotation and the presence of a dielectric intralayer on the spectral behavior of the optical force on a gold nanorod pair. The frequency spectrum of the optical force is obtained through the Maxwell stress tensor formulation and the full vectorial solution of electromagnetic waves. The common and the relative forces, which are defined through the optical force acting on each nanorod, are computed for different axial rotations and for different permittivity and thickness of the dielectric intralayer. We found that both the misalignment and the dielectric intralayer can be utilized to tailor the magnitude and direction of the relative optical force, providing a tunable attractive or repulsive response between the nanorods.