Modeling of THz Pump Induced Plasmonic Oscillations in Silicon Membranes

We present a one-dimensional charge density model for an oscillating “plasmon” in a 200 nm thick silicon membrane. The free carriers are generated using photoexcitation, then a single-cycle THz pump induces an oscillation of those carriers. The plasmonic oscillation is probed using a short relativistic electron bunch which is sensitive to the dipole field produced by the separation of charges. We compare the results of the model with measurements of the local field from ultrafast electron diffraction.