Abstract

Solid state lighting based on color mixing of plural forms of light emitting diodes or wavelength conversion due to phosphors have become one of the important consideration for energy saving. Plausible solution to the long-standing issues of power efficiency droop was recently suggested by the development of single-crystal phosphors [1] instead of ceramic powder, as well as deployment of diode laser instead of light emitting diode as the pump source [2]. Combination of these approaches has improved the quantum efficiency and thermal stability of white light emission. However, it would be desirable if spectral coverage of the aforementioned white light emission can be extended to the “warm” white region to render better color gamut.

© 2016 Japan Society of Applied Physics, Optical Society of America