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Proceedings Paper

Laser-activated remote phosphor conversion with ceramic phosphors
Author(s): Alan Lenef; John Kelso; Maxim Tchoul; Oliver Mehl; Jörg Sorg; Y. Zheng
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Paper Abstract

Direct laser activation of a remote phosphor, or LARP, is a highly effective approach for producing very high luminance solid-state light sources. Such sources have much smaller étendue than LEDs of similar power, thereby greatly increasing system luminous fluxes in projection and display applications. While several commercial products now employ LARP technology, most current configurations employ phosphor powders in a silicone matrix deposited on rotating wheels. These provide a low excitation duty cycle that helps limit quenching and thermal overload. These systems already operate close to maximum achievable pump powers and intensities. To further increase power scaling and eliminate mechanical parts to achieve smaller footprints, OSRAM has been developing static LARP systems based on high-thermal conductivity monolithic ceramic phosphors. OSRAM has recently introduced a static LARP product using ceramic phosphor for endoscopy and also demonstrated a LARP concept for automotive forward lighting1. We first discuss the basic LARP concept with ceramic phosphors, showing how their improved thermal conductivity can achieve both high luminous fluxes and luminance in a static configuration. Secondly, we show the importance of scattering and low optical losses to achieving high overall efficiency and light extraction. This is shown through experimental results and radiation transport calculations. Finally, we discuss some of the fundamental factors which limit the ultimate luminance achievable with ceramic converted LARP, including optical pumping effects and thermal quenching.

Paper Details

Date Published: 18 September 2014
PDF: 11 pages
Proc. SPIE 9190, Thirteenth International Conference on Solid State Lighting, 91900C (18 September 2014); doi: 10.1117/12.2061864
Show Author Affiliations
Alan Lenef, OSRAM SYLVANIA Inc. (United States)
John Kelso, OSRAM SYLVANIA Inc. (United States)
Maxim Tchoul, OSRAM SYLVANIA Inc. (United States)
Oliver Mehl, OSRAM Licht AG (Germany)
Jörg Sorg, OSRAM Licht AG (Germany)
Y. Zheng, OSRAM SYLVANIA Inc. (United States)

Published in SPIE Proceedings Vol. 9190:
Thirteenth International Conference on Solid State Lighting
Matthew H. Kane; Jianzhong Jiao; Nikolaus Dietz; Jian-Jang Huang, Editor(s)

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