Subject2D Materials Polaritons
Date2019.06.24(Mon) 10:30 am
SpeakerProf.Tony Low (Department of Electrical & Computer Engineering, University of Minnesota, Minneapolis, US)
PlaceE3-2, Room 2216
Recent years have observed a plethora of strong dipole type polaritonic excitations in 2D materials owing to the reduced screening. These polaritons can be sustained as electromagnetic modes at the interface between a positive and negative permittivity material. In the case of the plasmon-polaritons (e.g. in semi-metallic graphene), the negative permittivity is provided by the coherent oscillations of the free carriers. For exciton-polaritons (e.g. in semiconducting transition metal dichalcogenides, TMD) and phonon-polaritons (e.g. in diatomic hexagonal boron nitride, hBN), it is associated with their resonant optical absorption, resulting from a highly dispersive permittivity. These optical resonances can also result in a negative permittivity, albeit over a narrow spectral window. In this talk, I will discuss our recent efforts in understanding plasmons behavior in various 2D materials, such as graphene, black phosphorus, and transition metal dichalcogenides, and how these systems can also exhibit rich transport behavior, such as hyperbolic rays, non-reciprocal chiral propagation, time reversal of waves and coupling of light spin to induce one-way propagation. Lastly, I will conclude with the opportunities that 2D heterostructures might bring for polariton physics.
Biography: Tony Low is an associate professor and leads the theory & computational group at the department of Electrical & Computer Engineering at the University of Minnesota. Prior to this, Low worked as a research scientist at Columbia University and IBM Thomas J. Watson Research. While at IBM, from 2011-2014, Low served as an industry liaison to various Universities under the Semiconductor Research Consortium & National Science Foundation, with the goal of finding the next electronics switch. He obtained his doctoral degree from the National University of Singapore in 2008, and then a postdoctoral associate at Purdue University. Low received the McKnight Presidential Fellowship (2019), IBM Pat Goldberg Memorial Best Paper Award (2014), and the IBM Invention Award (2013).