Single crystal growth and property investigation of Dy3+ and Tb3+ co-doped Gd3Sc2Al3O12 (GSAG): multiple applications for GaN blue LD pumped all-solid-state yellow lasers and UV or blue light chip excited solid-state lighting

A high-quality Dy3+ and Tb3+ co-doped GSAG single crystal with a crystal size of phi 25 x 25 mm(3) has been grown successfully by the traditional Czochralski method. The crystal structure and effective segregation coefficient of Dy3+ in the GSAG host were revealed by powder X-ray diffraction, single crystal X-ray diffraction and energy dispersive spectroscopy, respectively. The thermal conductivity of the Dy,Tb:GSAG crystal at room temperature was determined to be as high as 4.8 W m(-1) K-1. The dislocation defects in the as-grown crystal were investigated by the chemical etching method. The full width at half maximum of the absorption band corresponding to the H-6(15/2) -> I-4(15/2) transition of Dy3+ at around 447 nm broadens up to 18.5 nm. The emission cross-section for the F-4(9/2) -> H-6(13/2) transition of Dy3+ at 585 nm is calculated to be 4.15 x 10(-21) cm(2). The resonance energy transfer mechanism between Dy3+ and Tb3+ has been identified and discussed. These results indicate that the Dy,Tb:GSAG crystal is very promising for blue laser diode pumped all-solid-state yellow lasers and UV or blue chip excited solid-state lighting.