The forces from coupled surface plasmon polaritons in planar waveguides.

We analytically investigate the forces due to Surface Plasmon Polariton (SPP) modes between finite and infinitely thick metal slabs separated by an air gap. Using the Drude model and experimentally determined values of the dielectric functions of gold and silver, we study how frequency dispersion and loss in the metals affects the behavior of the SPP modes and the forces generated by them. We calculate the force using the Maxwell Stress Tensor for both the attractive and repulsive modes.