Radiation pressure of active dispersive chiral slabs.

We report a mechanism to obtain optical pulling or pushing forces exerted on the active dispersive chiral media. Electromagnetic wave equations for the pure chiral media using constitutive relations containing dispersive Drude models are numerically solved by means of Auxiliary Differential Equation Finite Difference Time Domain (ADE-FDTD) method. This method allows us to access the time averaged Lorentz force densities exerted on the magnetoelectric coupling chiral slabs via the derivation of bound electric and magnetic charge densities, as well as bound electric and magnetic current densities. Due to the continuously coupled cross-polarized electromagnetic waves, we find that the pressure gradient force is engendered on the active chiral slabs under a plane wave incidence. By changing the material parameters of the slabs, the total radiation pressure exerted on a single slab can be directed either along the propagation direction or in the opposite direction. This finding provides a promising avenue for detecting the chirality of materials by optical forces.