Positive effect of deactivated ion Tb3+ and non-optical active ion Al3+ co-doping on the Dy3+: CaLaGa3O7 crystal as a promising 574 nm yellow laser crystal

Abstract

A deactivated ion Tb³⁺ and non-optical active ion Al³⁺ co-doped Dy³⁺: CaLaGa₃O₇ (abbr. as Dy/Tb: CLAGO) yellow laser crystal was successfully grown and studied. The band structure of CLAGO shows that the hybrid CLAGO matrix is suitable as luminescent materials. Before crystal grown, Dy/Tb: CLAGO polycrystals with different concentrations of Tb³⁺ were synthesized to select the optimal doping concentration of Tb³⁺ and the value is 0.2 at.%. Then, the Dy/Tb: CLAGO singly crystal was grown by Cz technology and the tetragonal structure was confirmed by XRD measurement. The effect of Tb³⁺ co-doping on the optical properties was investigated in detail. The excitation spectrum shows that the Dy/Tb: CLAGO can be effective pumped by a conventional 450 nm GaN LD. Under excitation at 450 nm, the emission spectrum not only contains the typical emissions of Dy³⁺, but also has a 543 nm emission band of Tb³⁺. In comparison to Dy: CLGO crystal, the Dy/Tb: CLAGO crystal possessed a larger emission cross-section (4.05×10^-21 cm²) at the central wavelength of 574 nm. In addition, due to the introduction of Tb³⁺, the population on the laser lower level of Dy³⁺: ⁶H_13/2 decreases, while the impact on the upper level (Dy³⁺: ⁴F_9/2) is minimal. These results suggest that the Dy³⁺/Tb³⁺ co-doped CaLa(Al/Ga)₃O₇ crystal could be an attractive host for 574 nm yellow laser under a conventional 450 nm LD.