Laser Diodes for Lighting Applications Combined with Phosphor and Fiber-Optics Technologies(<Special Issue>For the Further Spread of SSL and the Expansion of the Application Field)

Abstract

Ultra-high-luminance lamps using high-power blue laser diodes and phosphors for lighting applications are reviewed. The laser output is coupled efficiently into an optical fiber, and all the optical powers from the fibers are focused on a small phosphor area in a lamp structure apart from the lasers. One of the 5000lm lamp structures achieved luminance performance as high as 140Mcd/m^2. It is demonstrated that laser coherence of the diffused blue light can be actually suppressed as low as LEDs, measured as speckle contrast. This implies that the light quality of these lamps is similar to LEDs. We also analyze the reason why such low speckle contrast is achieved.