PhD Comprehensive Seminar | Kamran Akbari, Radiation from nanostructures induced by moving charged particles

M3-3103

Candidate

Kamran Akbari, Applied Mathematics, University of Waterloo

Title

Radiation from nanostructures induced by moving charged particles

Abstract

The central pillars of Nano-optics (or Nano-photonics) are light-matter interactions on the nanometer scale. Strong interaction between light and quasi-free electrons in matter gives rise to Plasmonics as a separate branch of Nano-photonics, which enables one to break the diffraction limit and concentrate light into deep-subwavelength volumes with huge field enhancements. Initially, noble metals were studied as qualified host materials in Plasmonics that can support collective electronic modes called surface plasmon polaritons. As the use of graphene is rapidly growing, new scientific and technological opportunities are opened in the context of Optoelectronics and Photonics. Highly doped graphene is considered to be a promising plasmonic material working in the mid-infrared and terahertz spectral ranges.

Excitation of surface plasmons by swift electrons has long been utilized in electron microscopes for experimental technique called electron-energy-loss spectroscopy (EELS) to investigate plasmonic properties of ultrathin, or two-dimensional electron systems. In electron microscopes it is possible to focus electron beams on subnanometer spots and probe the target response by analyzing electron energy losses or by detecting emitted radiation.

In this project, a theoretical model and mathematical foundation of EELS will be rendered. Specifically, we shall perform a deep analysis of retardation effects and transition radiation which is, basically, light emission induced by swift electrons. This mathematical model will be first applied to a single-layer graphene and then generalized to multi-layer graphene. Finally, we shall analyze the spectral probability densities of both the electron energy loss and the emitted radiation and draw conclusions on their applications for characterizing graphene-based nano-plasmonic devices.