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Photonic quasi-crystal LEDs: design, modelling, and optimisation

Photonic quasi-crystal LEDs: design, modelling, and optimisation
Photonic quasi-crystal LEDs: design, modelling, and optimisation
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.
0277-786X
64860R1-[10pp]
Charlton, M.D.B.
fcf86ab0-8f34-411a-b576-4f684e51e274
Zoorob, M.E.
01b3a61a-95c3-45d5-a06b-caa91c734cfd
Lee, T.
237fd996-0301-4620-aa6f-ffed6fcfd3f9
Charlton, M.D.B.
fcf86ab0-8f34-411a-b576-4f684e51e274
Zoorob, M.E.
01b3a61a-95c3-45d5-a06b-caa91c734cfd
Lee, T.
237fd996-0301-4620-aa6f-ffed6fcfd3f9

Charlton, M.D.B., Zoorob, M.E. and Lee, T. (2007) Photonic quasi-crystal LEDs: design, modelling, and optimisation. Proceedings of SPIE, 6486, 64860R1-[10pp]. (doi:10.1117/12.715025).

Record type: Article

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.

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Published date: January 2007
Additional Information: Invited paper

Identifiers

Local EPrints ID: 48704
URI: https://eprints.soton.ac.uk/id/eprint/48704
ISSN: 0277-786X
PURE UUID: 2032b49d-e45b-474f-8572-02422a08aef8

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Date deposited: 08 Oct 2007
Last modified: 13 Mar 2019 20:56

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Contributors

Author: M.D.B. Charlton
Author: M.E. Zoorob
Author: T. Lee

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