Investigation into the coupling of quantum dots to photonic crystal nanocavities at telecommunication wavelengths

L.P. Balet

Research output: ThesisPhd Thesis 3 (Research TU/e / Graduation NOT TU/e)

68 Downloads (Pure)

Abstract

Recently, the emission of single photons with emission wavelength in the 1.3 ??m telecommunication window was demonstrated for InAs quantum dots. This makes them strong candidates for applications such as quantum cryptography, and in a longer term, quantum computing. However, e??cient extraction of the spontaneous emission from semiconductors still represents a major challenge due to total internal re ection at the semiconductor/air interface. In particular, single photon sources based on quantum dots are plagued by low extraction e??ciency and poor coupling to single-mode ??bers, typically on the order of 10³ ?? - 104, which prevents their application to quantum communication. To seek a solution to this problem, this thesis work explores the integration of quantum dots, with emission at 1.3??m, in photonic crystal microcavities. Photons emitted in a mode of the cavity are funneled out of the semiconductor, and thus bypass the total internal re ection. In addition, the modi??ed density of electromagnetic states in the cavity a??ects the emission lifetime of a weakly coupled emitter: in resonance, we assist to an increase of the emission rate, known as the Purcell e??ect, that would allow faster data transmission. Photonic crystal microcavities conveniently address this objective as they provide modes with the required small volumes and high quality factors. They also allow the engineering of the far??eld pattern of the cavity modes, and thus of the collection e??ciency. In the following pages, after brie y reviewing single photon emitters, the Purcell e??ect, and photonic crystal cavities, we present our results on the coupling of quantum dots to photonic crystal cavities. We report on the di??erent strategies we used to control the tuning between the cavity mode and the quantum dot emission frequency. We also show our e??orts in improving the collection of coupled photons by engineering the shape of the microcavity. Finally, we present our time-resolved measurements demonstrating the Purcell e??ect under optical and electrical operation. Keywords: semiconductor, quantum dot, photonic crystal, microcavity, Purcell e??ect, light emitting diode (LED), micro-photoluminescence, time-resolved spectroscopy 7
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Ecole Polytechnique Fédérale de Lausanne
Supervisors/Advisors
  • Fiore, Andrea, Copromotor
  • Martin, O., Promotor, External person
Award date29 May 2009
Place of PublicationLausanne
Publisher
Publication statusPublished - 2009

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