The remarkable properties of excitons in transition-metal-dichalcogenides (TMDs), together with the ability to readily control their charge carriers, have attracted a significant amount of interest in recent years. Despite the atomic dimensions of the hosting 2D semiconductors, TMD excitons exhibit strong interaction with light, both in absorption and photoemission processes, and practically dominate the optical response of these 2D materials. In this talk, I will introduce several approaches for achieving extremely strong light-exciton interactions. First, by optical and electrical manipulation of TMD excitons inside a van der Waals heterostructure cavity , second, via the formation of highly-confined, in-plane exciton polaritons , and third, through the realization of valley-polarized hyperbolic exciton polaritons .
These enhanced light–exciton interactions may provide a platform for studying excitonic phase-transitions, quantum nonlinearities and the enablement of new possibilities for 2D semiconductor-based optoelectronic devices.
 I. Epstein et al, "Near-unity Light Absorption in a Monolayer WS2 Van der Waals Heterostructure Cavity", Nano letters 20 (5), 3545-3552 (2020).
 I. Epstein et al, "Highly Confined In-plane Propagating Exciton-Polaritons on Monolayer Semiconductors", 2D Materials 7, 035031 (2020).
 T. Eini, T. Asherov, Y. Mazor, and I. Epstein, "Valley-polarized Hyperbolic Exciton Polaritons in Multilayer 2D Semiconductors at Visible Frequencies", Phys. Rev. B 106, L201405 (2022).