Magnetic bias-driven modulation of graphene for tunable gyrotropic and magnetoplasmon devices

This work investigates the electromagnetic response of graphene subjected to a magnetic bias field under harmonic modulation. Two representative configurations are analyzed: a small square patch to examine scattering behavior, and a graphene microstrip to explore plasmonic propagation. A modified FDTD algorithm is developed to accurately model the time-varying magnetic bias within the full-wave simulation. For the square patch, the quasi-normal modes are extracted to assess the shift of the scattered field’s main lobe as a function of the applied magnetic bias, and full-wave analyses reveal notable harmonic generation, especially for stronger modulation amplitudes. In the microstrip configuration, modal analysis of the cross-section provides the dispersion characteristics of the supported modes, while full-wave simulations highlight that the modulation effects are more evident than in the scattering case. Furthermore, the harmonically varying bias restores the symmetric plasmonic propagation, demonstrating the potential of time-varying magnetic control in dynamic graphene-based photonic devices.