White light source with laser-excited phosphor

The principles of operation of a white light source based on a remote phosphor, made of cerium-doped yttrium aluminium garnet (YAG : Ce³⁺), whose luminescence is excited by a blue laser diode, are considered. The colorimetric and photometric characteristics of phosphors of different types are analysed as functions of the phosphor film thickness. The following parameters are obtained at an output power of 1 W and a wavelength of 445±3 nm in the cw regime: luminous flux of 165 lm, correlated colour temperature of 5595 K, colour rendering index of 66, colour coordinates x = 0.3303 and y = 0.3427, luminous efficiency of 165 lm W^-1, and light efficacy of 30 lm W^-1. These characteristics are comparable with similar parameters of commercial white LEDs. (fluorescence and photogeneration)