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

Abstract

A high-quality Dy³⁺ and Tb³⁺ co-doped GSAG single crystal with a crystal size of ϕ25 × 25 mm³ 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 ⁶H_15/2 → ⁴I_15/2 transition of Dy³⁺ at around 447 nm broadens up to 18.5 nm. The emission cross-section for the ⁴F_9/2 → ⁶H_13/2 transition of Dy³⁺ at 585 nm is calculated to be 4.15 × 10⁻²¹ cm². 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.