Long-range ballistic propagation of 80$\%$-excitonic-fraction polaritons in a perovskite metasurface at room temperature

TL;DR

This study demonstrates room-temperature long-range propagation of high-excitonic-fraction polaritons in perovskite metasurfaces, enabling potential advancements in all-optical devices through ballistic polariton transport.

Contribution

The paper reports the first experimental observation of over hundreds of micrometers of polariton propagation at room temperature with 80% excitonic fraction in a perovskite metasurface, facilitated by large Rabi splitting and metasurface design.

Findings

Long-range propagation (> hundreds of micrometers) of polaritons at room temperature.

High excitonic fraction (~80%) polaritons can propagate effectively.

Metasurface design enables directional control of polariton flow.

Abstract

Exciton-polaritons, hybrid light-matter elementary excitations arising from the strong coupling regime between excitons in semiconductors and photons in photonic nanostructures, offer a fruitful playground to explore the physics of quantum fluids of light as well as to develop all-optical devices. However, achieving room temperature propagation of polaritons with a large excitonic fraction, which would be crucial, e.g., for nonlinear light transport in prospective devices, remains a significant challenge. } Here we report on experimental studies of exciton-polariton propagation at room temperature in resonant metasurfaces made from a sub-wavelength lattice of perovskite pillars. Thanks to the large Rabi splitting, an order of magnitude larger than the optical phonon energy, the lower polariton band is completely decoupled from the phonon bath of perovskite crystals. The long lifetime of these cooled polaritons, in combination with the high group velocity achieved through the metasurface design, enables long-range propagation regardless of the polariton excitonic fraction. Remarkably, we observed propagation distances exceeding hundreds of micrometers at room temperature, even when the polaritons possess a very high excitonic component, approximately {80}$\%$. Furthermore, the design of the metasurface introduces an original mechanism for directing uni-directional propagation through polarization control. This discovery of a ballistic propagation mode, leveraging high-speed cooled polaritons, heralds a promising avenue for the development of advanced polaritonic devices.