Electrically switchable in-plane anisotropic exciton-polariton in a van der Waal semiconductor

Tailoring of the propagation dynamics of exciton-polaritons in two-dimensional quantum materials has shown extraordinary promise to enable nanoscale control of electromagnetic fields. Varying permittivities along crystal directions within layers of material systems, can lead to an in-plane anisotropic dispersion of polaritons. Exploiting this physics as a control strategy for manipulating the directional propagation of the polaritons is desired and remains elusive. Here, we explore the in-plane anisotropic exciton-polariton propagation in a group-IV monochalcogenide semiconductor which forms ferroelectric domains and exhibits room-temperature excitonic behavior. Exciton-polaritons with their propagation dynamics and dispersion studied. This propagation of exciton-polaritons allows for nanoscale imaging of the in-plane ferroelectric domains. Finally, we demonstrate the electric switching of the exciton-polaritons in the ferroelectric domains of this complex vdW system. The study suggests that systems like group-IV monochalcogenides could serve as excellent ferroic platforms for actively reconfigurable polaritonic optical devices.