Coupling of single organic molecules to photonic micro-structures
File(s)
Author(s)
Boissier, Sebastien
Type
Thesis
Abstract
Dopant molecules in organic crystals can be triggered to create single photons with certainty. This basic principle is currently being leveraged to develop a new generation of photonic components capable of delivering single photons to optical hardware. In turn, these single-photon sources are enabling increasingly sophisticated technologies based on the quantum nature of photons, in areas such as quantum computation and quantum cryptography. In this thesis, I present my work towards realising an organic single-photon source using dibenzoterrylene (DBT) molecules in anthracene crystals. To realise a deterministic single-photon source with molecules, we have to address two main challenges. First, it is necessary to collect all the photons emitted by a single molecule into a propagating optical mode. To achieve this, I have investigated methods to place single DBT molecules close to the field maximum of single-mode waveguides. I describe our strategy which consists of overlaying microfluidic channels on top of silicon-nitride ridge waveguides. With this geometry, targeted crystallisation of DBT-doped anthracene occurs in small gaps running across the waveguides. We probe the system using coherent single-molecule spectroscopy and estimate that 7% of the molecular emission is coupled to the waveguide modes for one of our fabricated devices. The second challenge is to turn DBT molecules into coherent two-level systems. The vibrational spectrum of DBT prevents the system from generating indistinguishable single-photons without filtering of the emission. However, the reduction in single-photon efficiency due to filtering can be improved by selectively accelerating the radiative decay of the zero-phonon line. I discuss how such an enhancement is possible using optical cavities and how both challenges can be addressed with this approach. Finally, I introduce a new design for a vertically-emitting cavity with an active layer of DBT-doped anthracene.
Version
Open Access
Date Issued
2019-09
Date Awarded
2020-02
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Hinds, Edward A.
Clark, Alex S.
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)