Dynamic optical activity and self-oscillation in torsional metamaterials

We study the nonlinear dynamic properties of coupled torsional meta-molecules. We find that this structure may exhibit self-oscillation behaviour, and we analyse two different mechanisms leading to this effect. Contrary to many previously studied optomechanical systems, self-oscillations of torsional meta-molecules can be extremely robust against mechanical damping and they can be manipulated by the polarisation of electromagnetic waves. We also study the dynamic nonlinear optical activity arising in the system and its active control.