High brightness illumination based on laser light diffusion with Mie scattering

Abstract

Limited luminous flux per wafer area of light emitting diodes (LEDs) for high power solid state illumination causes some packaging real estate issues. This problem can be tackled with laser diodes (LDs). At high current densities, LDs offer higher efficiency, however with very low etendue and divergent angle. This significantly increases the complexity of color conversion for white light generation. Concentrated light can carbonize the color conversion unit and have high speckle contrast. These problems can be addressed by efficient diffusion of the laser beam and this paper is aimed to introduce the first laser diffusion system based on TiO2 Mie particles. Based on a series of ray tracing simulations, an idealized cost-effective system is modeled and results showed an almost lossless diffusion with a guiding system based on reflection resulting in an almost uniform irradiance level with only 17% power loss. Furthermore, offered design can reduce the challenges for the compact packaging of white LDs by eliminating the heat sink for color conversion coating and enabling a safe light intensity for utilizing quantum dots for color engineering.