Enhancing brightness of Lambertian light sources with luminescent concentrators: the light extraction issue

T. Gallinelli (1) , A. Barbet (2) , F. Druon (2) , François Balembois (2) , Patrick Georges (2) , T. Billeton (1) , S. Chénais (1) , S. Forget (1)

1 LPL - Laboratoire de Physique des Lasers
2 Laboratoire Charles Fabry / Lasers

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.)

Domaines: Optique / photonique

T. Gallinelli, A. Barbet, F. Druon, François Balembois, Patrick Georges, et al.. Enhancing brightness of Lambertian light sources with luminescent concentrators: the light extraction issue. Optics Express, 2019, 27 (8), pp.11830. ⟨10.1364/OE.27.011830⟩. ⟨hal-02358687⟩