Temporal Dynamics of an Asymmetrical Dielectric Nanodimer Wrapped with Graphene

We theoretically and numerically investigate the temporal dynamics of a nanodimer system consisting of a pair of graphene-wrapped dielectric nanospheres with tunable radii. Considering that symmetry breaks on resonant frequencies, we derive the temporal kinetic equations in an asymmetric form by utilizing the dispersion relation method in dipole limit. The bifurcation diagrams achieved via the analysis on the linear instability and numerical solutions can quantitatively characterize the complex coexistences of stationary and dynamical behaviors in this dimer system, and the asymmetry apparently can increase the number of regimes with the periodic self-oscillation state or chaos. Furthermore, we find that the indefinite switching not only can be triggered among the stationary steady solutions, but it also universally exists among all the possible solutions in a coexistent regime. The switching can be tuned by applying a hard excitation signal with different durations and saturation values. Our results may provide new paths to realize a nonlinear nanophotonic device with tunable dynamical responses or even multi-functionalities.