We have investigated the transport of light through slabs that bothscatter and strongly absorb, a situation that occurs in diverseapplication fields ranging from biomedical optics, powder technology, tosolid-state lighting. In particular, we study the transport of light inthe visible wavelength range between 420 and 700 nm through siliconeplates filled with YAG:Ce3+phosphor particles, that even re-emitabsorbed light at different wavelengths. We measure the totaltransmission, the total reflection, and the ballistic transmission oflight through these plates. We obtain average single particle propertiesnamely the scattering cross-section, the absorption cross-section, andthe anisotropy factor using an analytical approach, namely the P3approximation to the radiative transfer equation. We verify theextracted transport parameters using Monte-Carlo simulations of thelight transport. Our approach fully describes the light propagation inphosphor diffuser plates that are used in white LEDs and that reveal astrong absorption (L/la > 1) up to L/la = 4, where L is the slabthickness, la is the absorption mean free path. In contrast, the widelyused diffusion theory fails to describe this parameter range. Ourapproach is a suitable analytical tool for industry, since it provides afast yet accurate determination of key transport parameters, and sinceit introduces predictive power into the design process of white lightemitting diodes.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-20-A906

M. L. Meretska, R. Uppu, G. Vissenberg, A. Lagendijk, W. L. IJzerman, and W. L. Vos

2017

09/2017

Opt. Express

25

A906-A921

diffusion, Light-emitting diodes, lighting, Mie theory, multiplescattering, Rare-earth doped materials