Slow reflection and two-photon generation of microcavity exciton-polaritons

TL;DR

This paper demonstrates slow reflection of exciton-polaritons in a microcavity, measures their long lifetime, and introduces two-photon excitation to generate polaritons, enabling potential modulation of absorption.

Contribution

It presents the first observation of slow reflection of polaritons and measures their lifetime, along with a novel two-photon generation method for polaritons in microcavities.

Findings

Polaritons have a lifetime of 180 ps.

Polaritons propagate millimeters in the cavity.

Two-photon excitation can generate polaritons.

Abstract

We resonantly inject polaritons into a microcavity and track them in time and space as they feel a force due to the cavity gradient. This is an example of "slow reflection," as the polaritons, which can be viewed as renormalized photons, slow down to zero velocity and then move back in the opposite direction. These measurements accurately measure the lifetime of the polaritons in our samples, which is 180 $\pm$ 10 ps, corresponding to a cavity leakage time of 135 ps and a cavity $Q$ of 320,000. Such long-lived polaritons propagate millimeters in these wedge-shaped microcavities. Additionally, we generate polaritons by two-photon excitation directly into the polariton states, allowing the possibility of modulation of the two-photon absorption by a polariton condensate.