Controlling excitons in 2D heterostructures and plasmonic devices

Abstract

Over the past decade, excitonic effects in two-dimensional transition metal dichalcogenide semiconductors such as MoS2 and WSe2 have been intensely studied. Currently, there is significant interest in understanding how to control excitons in heterostructures and on-chip optical structures that have potential applications to excitonic and optical information processing devices. In this presentation, I will discuss our recent work exploring the nature of the moire trapping potential in MoSe2-WSe2 heterostructures, where the interlayer exciton photoluminescence exhibits a strong temperature dependence. I will also discuss our work demonstrating coupling between organic PTCDA molecular excitons and monolayer WSe2 excitons, which manifests as a ~20 times enhancement of the PTCDA Raman scattering efficiency. Finally, I will report on our recent studies on 2D semiconductor plasmonic structures composed of propagating surface plasmon polaritons (SPPs) coupled to monolayer WSe2 excitons. In our new “cross geometry” structures, we are able to explore the nonlinear exciton response of both co- and cross- propagating SPPs. In these devices, we observe a large (near unity) differential transmission response and population pulsation resonances that are dependent on the direction of SPP propagation.