Subfemtosecond and Nanometer Plasmon Dynamics with Photoelectron Microscopy: Theory and Efficient Simulations

We develop a theoretical model of the excitation and interference of surface plasmon polariton (SPP) waves with femtosecond laser pulses and use the model to understand the features in images from subfemtosecond time-resolved two-photon photoelectron microscopy (2PPE–PEEM). The numerically efficient model is based on the optics of SPP modes on multilayer thin films and takes account of the excitation and interference by the incident light, its polarization, the boundary shape on the film where the plasmons are generated, the pulsed form of the excitation and the time integration associated with the PEEM method. The model explains the dominant features observed in the images including the complex patterns formed in experiments involving orbital angular momentum. The model forms the basis of an efficient numerical method for simulating time-resolved 2PPE–PEEM images of SPP wave propagation. The numerics is extremely fast, efficient, and accurate, so that each image can take as little as a few seconds to calculate on a laptop computer, enabling entire PEEM movies to be calculated within minutes.