A Hybridizable Discontinuous Galerkin Method for Time-Modulated Drude--Lorentz Media

Abstract: We formulate and analyze a hybridizable discontinuous Galerkin (HDG) method for Maxwell's equations coupled to four time-modulated Drude--Lorentz models: modulated in-coupling, modulated polarization density, modulated current density, and modulated effective mass. The use of electric displacement and model-dependent continuous material states gives a common treatment of temporal interfaces while preserving the distinct physical transmission rules. We derive energy and stability estimates, establish spatial and event-aligned time-error bounds, and separate time-integration error from error caused by misplaced switching times. Numerical experiments in three dimensions and in reduced modal systems confirm the predicted spatial, temporal, and switch-timing behavior, including the field-jump effect specific to the polarization-density model.