Nonlinear Dynamics of Optically Excited Chiral Nano-Spheroid in a Stationary Fluid

We investigate the nonlinear mechanical motion of a chiral nanoparticle suspended in stationary fluid induced by a linearly polarized electromagnetic field with a rotating polarization axis. Our analysis makes use of the time-averaged optical torque, which yields a set of three nonlinear equations for the angular velocities of the 3D rotating chiral particle in terms of its time-dependent Euler angles. The effect of electromagnetic chirality dramatically changes the qualitative behavior of the optical torque. It is also shown that chirality manifests itself in the non-invariance of the particle's optical torque with respect to the direction of rotation of light polarization. In order to preserve the invariant behavior, a chiral duality condition must be enforced. Some relevant experimental observations and few practical applications of predicted effect are also mentioned and discussed.