YAG and greenYAG+nitride properties for white-light generation using a blue laser diode

The phosphor excitation by blue laser diode and an influence of its irradiation on the material were investigated. Two types of materials were elaborated to perform these experiments—yellow phosphor (YAG) and green phosphor mixed with nitride phosphor (GYAG). These phosphors were packaged into silicone plates, having different thickness and concentration in silicon resin. The results from exciting the phosphor by blue laser present that emission of converted light increases when concentration and thickness increase. Also, the dependency of these two parameters on optical power shows certain behavior. Subsequently, the concentration and thickness were replaced by particle number in sample. It revealed that the dependency of the particle numbers on the optical power can replace the conventional parameters as thickness or concentration. Results show that correlated color temperature finds it dependency on number of particles also. In addition, it turned out, that for each of the material, there might exist an optimal particle number for the maximum luminous power. Finally, the influence of the irradiation of blue laser diode on the materials was investigated. After intensive irradiation for 30 min, we observed that the efficiency of light conversion decreases. It can be caused by damages made by laser on particles. Results show parts of nitride (650 nm) conversion decrease less than yellow or green phosphor. Less affection of irradiation can be explained by nitride being very covalent material, more resistant to modification. Also, we found that there is no fundamental modification of material structure because of no changing in spectrum shape of converted light.