▎ 摘　　要

This paper studies the propagation of plasmons on graphene when the Drude weight is varied in time. The phenomenon of plasmon propagation is modeled by considering the graphene as a conductive sheet. Under the assumption that the field is oscillatory in the direction parallel to the sheet, it can be shown that the coupled electromagnetic field can be reduced to a single time-dependent equation describing the current density on the sheet. The current density depends on the wave number xi and is shown to satisfy an integro-differential equation in time. Well-posedness for this equation is established. A numerical scheme to solve the current equations based on convolution quadrature is developed. An approximate equation, based on large xi with the physical interpretation of a quasi-static approximation, is derived and its accuracy assessed. The phenomena of wave reversal and parametric amplification are studied. Numerical calculations are conducted to address several theoretical issues as well as to demonstrate the main ideas.