A stable, single-photon emitter in a thin organic crystal for application to quantum-photonic devices

TL;DR

This paper introduces a method to produce ultra-thin, doped organic crystals with stable single-photon emitters suitable for integration into quantum photonic devices, demonstrating their high brightness and photostability.

Contribution

It presents a novel vapor growth technique for thin anthracene crystals doped with dibenzoterrylene molecules, enabling reliable single-photon emission in nanophotonic applications.

Findings

Emitters are stable and deliver over 10^12 photons without bleaching.

The molecules exhibit well-defined polarization aligned with crystal axes.

Radiative lifetime and saturation intensity are consistent across the crystal.

Abstract

Single organic molecules offer great promise as bright, reliable sources of identical single photons on demand, capable of integration into solid-state devices. It has been proposed that such molecules in a crystalline organic matrix might be placed close to an optical waveguide for this purpose, but so far there have been no demonstrations of sufficiently thin crystals, with a controlled concentration of suitable dopant molecules. Here we present a method for growing very thin anthracene crystals from super-saturated vapour, which produces crystals of extreme flatness and controlled thickness. We show how this crystal can be doped with a widely adjustable concentration of dibenzoterrylene (DBT) molecules and we examine the optical properties of these molecules to demonstrate their suitability as quantum emitters in nanophotonic devices. Our measurements show that the molecules are available in the crystal as single quantum emitters, with a well-defined polarisation relative to the crystal axes, making them amenable to alignment with optical nanostructures. We find that the radiative lifetime and saturation intensity vary little within the crystal and are not in any way compromised by the unusual matrix environment. We show that a large fraction of these emitters are able to deliver more than $10^{12}$ photons without photo-bleaching, making them suitable for real applications.