Design of Phosphor White Light Systems for High-Power Applications

We developed a strategy that transforms phosphor down-converting white light sources from low power systems into efficient high-power ones. To incorporate multiple phosphors, we generalized and extended a phosphor layer model, which we term CCAMP (color correction analysis for multiple phosphors). CCAMP describes both the scattering and saturation of phosphor materials and allows modeling of different layered structures. We employed a phosphor mixture comprising YAG:Ce and K2TiF6:Mn4+ to illustrate the effectiveness of the model. YAG:Ce's high density and small particle size produce a large amount of scattering, while the long (4.8 ms) photoluminescent lifetime of K2TiF6:Mn4+ results in saturation at high pump power. By incorporating experimental photophysical results from the phosphors, we modeled our system and chose the design suitable for high-power applications. We report the first solid-state phosphor system that creates warm white light emission at powers up to 5 kW/cm(2). Furthermore, at this high power, the system's emission achieves the digital cinema initiative (DCI) requirements with a luminescence efficacy improvement of 20% over the stand-alone ceramic YAG:Ce phosphor.