Photons, plasmons, and polaritons: optical phenomena in complex materials

Abstract: When light interacts with complex materials, we can excite a variety of modes including plasmon polaritons and optical phonons. In layered materials, these modes can interact with each other to produce hybrid excitations resulting in novel optical phenomena such as negative refraction, extreme light confinement, and preferential thermal emission. In this talk, I will discuss our work on the growth of topological insulator thin films and heterostructures by molecular beam epitaxy. Topological insulators have two-dimensional surface states that house massless electrons, and the plasmon polaritons in these materials show unusual properties. I will discuss the dispersion of these modes and show record high mode indices and extremely long polariton lifetimes. Using MBE, we can then grow layered structures comprising multiple topological and normal insulators, resulting in hybrid coupled plasmon modes. I will also describe our work on semiconductor hyperbolic metamaterials, which are layered materials comprising alternating metallic and dielectric materials. I will show negative refraction in these materials, their ability to house their own complex plasmon polariton modes, show preferential thermal emission, and strongly couple to embedded quantum wells.

Bio: Prof. Law is the Norris B. McFarlane Faculty Career Development Associate Professor in the department of Materials Science and Engineering at Penn State University, and she holds affiliate appointments in the Penn State Department of Physics and the Institute for Energy and the Environment. She is the Director of Education, Outreach, and Diversity programs for the PSU Two-Dimensional Crystal Consortium and is an Associate Editor for the Journal of Vacuum Science and Technology. She received her B.S. in Physics from Iowa State University and her Ph.D. in Physics from the University of Illinois Urbana Champaign. She then held a postdoctoral position in the Electrical Engineering department at Illinois before moving to the University of Delaware as an Assistant Professor. Prof. Law has won the North American Molecular Beam Epitaxy Young Investigator award, the Department of Energy Early Career award, the AVS Peter Mark Memorial Award, the International Conference on Molecular Beam Epitaxy Young Investigator Award, and the Presidential Early Career Award for Scientists and Engineers (PECASE).