Strong exciton-photon coupling with colloidal nanoplatelets in an open microcavity

TL;DR

This paper demonstrates room temperature strong exciton-photon coupling in colloidal CdSe nanoplatelets within an open microcavity, revealing large vacuum Rabi splittings and potential for advanced photonic devices.

Contribution

It reports the first observation of strong coupling of excitons in colloidal nanoplatelets with photonic modes at room temperature, including measurement of transition dipole moments.

Findings

Vacuum Rabi splittings of 66 and 58 meV for heavy and light hole excitons

Observation of polariton-mediated hybridization of exciton transitions

Computed transition dipole moment of 575 D for a nanoplatelet exciton

Abstract

Colloidal semiconductor nanoplatelets exhibit quantum size effects due to their thickness of only few monolayers, together with strong optical band-edge transitions facilitated by large lateral extensions. In this article we demonstrate room temperature strong coupling of the light and heavy hole exciton transitions of CdSe nanoplatelets with the photonic modes of an open planar microcavity. Vacuum Rabi splittings of $66 \pm 1$ meV and $58 \pm 1$ meV are observed for the heavy and light hole excitons respectively, together with a polariton-mediated hybridisation of both transitions. By measuring the concentration of platelets in the film we compute the transition dipole moment of a nanoplatelet exciton to be $\mu = (575 \pm 110)$ D. The large oscillator strength and fluorescence quantum yield of semiconductor nanoplatelets provide a perspective towards novel photonic devices, combining polaritonic and spinoptronic effects.