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Proceedings Paper

Photonic quasi-crystal LEDs: design, modelling, and optimisation
Author(s): M. D. B. Charlton; M. E. Zoorob; T. Lee
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Paper Abstract

In this paper we investigate improvement in performance attainable by etching Photonic Crystals and Photonic Quasi-Crystals into the top emitting surface of LEDs. We describe the physical mechanisms of extraction enhancement through ordered surface patterning and investigate benefits in terms of total extraction enhancement, beam directionality, and far field beam quality. Factors such as lattice geometry, etch depth, and epitaxy thickness are investigated. We show that a great variety of far field beam profiles of benefit in applications such as projection TV light engines and direct flat panel display illumination can be obtained simply by adjusting geometric design parameters. Our results show that PCs can provide significant improvement in extraction enhancement for applications requiring non Lambertian beam shapes when etched into standard "production line" epitaxy wafers in comparison to "state of the art" surface roughened thin-GaN LED devices. We investigate PC beam steering effects in these devices confirming that PCs do in fact re-direct light from trapped modes confined within the epi-structure to radiating modes. We also show that by tailoring the thickness of the epi-structure to complement the properties of the photonic crystal, extraction enhancement can be improved by a factor of 9 for some applications.

Paper Details

Date Published: 13 February 2007
PDF: 10 pages
Proc. SPIE 6486, Light-Emitting Diodes: Research, Manufacturing, and Applications XI, 64860R (13 February 2007); doi: 10.1117/12.715025
Show Author Affiliations
M. D. B. Charlton, Univ. of Southampton (United Kingdom)
Mesophotonics Ltd. (United Kingdom)
M. E. Zoorob, Mesophotonics Ltd. (United Kingdom)
T. Lee, Mesophotonics Ltd. (United Kingdom)

Published in SPIE Proceedings Vol. 6486:
Light-Emitting Diodes: Research, Manufacturing, and Applications XI
Klaus P. Streubel; Heonsu Jeon, Editor(s)

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