Eutectic phosphor for high‐power excitation

High‐power blue‐emitting laser diodes have been used in projectors and lighting systems as excitation sources for yellow‐emitting phosphors. These phosphors must be robust and should not exhibit thermal quenching. In this work, we developed a durable eutectic phosphor consisting of single‐crystal Ce‐doped yttrium aluminum garnet (Ce:YAG) phosphor and Al2O3 (sapphire), with a thermal conductivity greater than 20 W/(m·K). This eutectic phosphor is named EPOCH‐Neo. EPOCH‐Neo specimens were cut from a large crystal substrate prepared by an edge‐defined film‐fed growth method. We evaluated the optical properties of EPOCH‐Neo specimens and the optical uniformity of an EPOCH‐Neo substrate. In addition, to control the chromaticity, the Y‐sites of Ce:YAG were doped with Gd at concentrations as high as 50% and the chromaticity and thermal characteristics of the resultant phosphors were evaluated. Moreover, the characteristics of a device composed of EPOCH‐Neo on a heatsink under blue laser excitation were examined. The results showed that EPOCH‐Neo is a durable phosphor suitable for use in high‐power‐excitation applications. High‐power blue‐emitting laser diodes have been applied to projectors and lighting systems as excitation sources for yellow‐emitting phosphors. These phosphors must be robust and should not exhibit thermal quenching. This work developed durable eutectic phosphors with a thermal conductivity of above 20 W/m·K.