Small size microcavity pillars with elliptical cross section and high quality factors Q are reported and are shown to provide nearly 100% linearly polarized single photon sources. It is shown that the polarization of the emission of quantum dots embedded within the pillars can be controlled by using the coupling of the dot emission with the photonic modes. A notable dependence of the Q value is found on the polarization of the mode even though calculations of the mode profiles show that the electric field distribution is very similar.

Observation of a very high-quality factor (Q) of ∼30,000 is reported for a planar semiconductor microcavity grown by molecular-beam epitaxy using in situ optical monitoring. The very high Qs are measured in pillars of 5–10μm diameter, and are approximately a factor of 3 higher than measured in planar structures before etching. The higher values in the pillars are ascribed to the elimination of the effects of in-plane dispersion, diffraction, and lateral inhomogeneities, thus allowing the intrinsic Q of the planar structure to be observed. Spectrally resolved mode mapping is reported, accounting qualitatively for the decrease of Q with increasing mode number in the pillars.

ReuseUnless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. AbstractWe show that the polarization of the emission of a single quantum dot embedded within a microcavity pillar of elliptical cross section can be completely controlled and even switched between two orthogonal linear polarizations by changing the coupling of the dot emission with the polarized photonic modes. We also measure the spatial profile of the emission of a series of pillars with different ellipticities and show that the results can be well described by simple theoretical modeling of the modes of an infinite length elliptical cylinder.

The degenerate fundamental mode of a microcavity pillar structure with circular cross section splits into two linearly polarized modes when the shape is changed to elliptical. The quality factor Q of these modes is very different. This letter demonstrates that the high Q mode provides better values of the figure of merit for strong coupling applications, Q∕V), where V is the modal volume, compared to values obtainable in circular structures. The difference in Q is shown to be a consequence of the polarization dependence of the losses through the microcavity mirrors.

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