Open AccessEnhancing brightness of Lambertian light sources with luminescent concentrators: the light extraction issue
Author(s) -
Thomas Gallinelli,
Adrien Barbet,
Frédéric Druon,
François Balembois,
Patrick Georges,
Thierry Billeton,
Sébastien Chénais,
Sébastien Forget
Publication year - 2019
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.27.011830
Subject(s) - optics , brightness , distributed ray tracing , light emitting diode , wedge (geometry) , ray tracing (physics) , materials science , optoelectronics , light intensity , ray , slab , nonimaging optics , physics , geophysics
Luminescent concentrators (LC) enable breaking the limit of geometrical concentration imposed by the brightness theorem. They enable increasing the brightness of Lambertian light sources such as (organic) light-emitting diodes. However, for illumination applications, light emitted in the high-index material needs to be outcoupled to free space, raising important light extraction issues. Supported by an intuitive graphical representation, we propose a simple design for light extraction: a wedged output side facet, breaking the symmetry of the traditional rectangular slab design. Angular emission patterns as well as ray-tracing simulations are reported on Ce:YAG single crystal concentrators cut with different wedge angles, and are compared with devices having flat or roughened exit facets. The wedge output provides a simple and versatile way to simultaneously enhance the extracted power (up to a factor of 2) and the light directivity (radiant intensity increased by up to 2.2.).