UC San Diego

This work deals with the modeling of collective mode phenomena in two-dimensional materials, especially of modes with momenta greatly exceeding the phonon wavenumber. The first chapter contains a brief review of the electrodynamic description of light-matter coupling. In the latter parts of that chapter, this formalism is applied to model and quantitatively describe the results of experimental measurements utilizing specialized near-field microscopy. A model for the experimentally observed near-field signal is built and analyzed for a system with additional carriers from optical pumping, for a system with wavelength-size features, and for a system featuring strong coupling between collective modes in optically anisotropic systems.

The second chapter contains a theoretical description of certain near-field photocurrent experiments. We build a model for a class of these experiments, connecting the results for each type to each other. We also derive a theorem connecting different the signal from different types of near-field experiments on the same material. We also analyze several different mechanisms for the generation of photocurrent and give their scaling with relevant experimental parameters. In addition, existing experimental results are compared with the output of the model.