Transport of light through white-LED phosphor plates

Abstract

Energy efficient generation of white light has become an important societal issue in recent years. The technology of white-light emitting diodes (LEDs) is one of the main directions (Akasaki I, Amano H, Nakamura S, Blue LEDs – filling the world with new light, http://www.nobelprize.org/, 2014; Schubert EF, Light emitting diodes. Cambridge: Cambridge University, 2006). Key challenges in the white LED usage are understanding scattering, absorption and emission from ab-initio, and extracting the transport properties in the region where both emission and absorption overlap. Physical understanding of multiple light scattering in the LED provides tools to extract optical parameters of this system, and greatly simplify the LED design process. In this work we have been able to measure the total transmission, using a novel technique, in the region where emission and absorption overlap, and to extract transport parameters in the whole visible range.