Enhancement of the optical properties of a Dy3+:Sr3Gd2(BO3)4 crystal by Ca2+ co-doping

Abstract

In this work, polycrystalline Dy3+:(Sr1-xCax)3Gd2(BO3)4 (x = 0–0.9) compounds doped with different concentrations of Ca2+ were synthesized by solid-state reaction. On the basis of their structural and spectral data, the optimal Ca2+ ions doping concentration of 60 at.% was determined. Then the Dy3+:(Sr0.4Ca0.6)3Gd2(BO3)4 crystal was obtained by the Czochralski (Cz) method. The crystal has a relatively high absorption cross-section at 453 nm, which is 0.98 × 10−21 cm2 (E//c) with a full width at half maximum (FWHM) of 9 nm (E//c). The maximum emission cross-section of the 4F9/2 → 6H13/2 transition at 576 nm is 5.62 × 10−21 cm2 (E//c) with a FWHM of 14 nm. The fluorescence quantum efficiency is 52.5 %. Compared with the Dy3+:Sr3Gd2(BO3)4 crystal, the emission cross-section and fluorescence quantum efficiency of the Dy3+:(Sr0.4Ca0.6)3Gd2(BO3)4 crystal have been significantly improved. These further increase the possibility of the crystal emitting a yellow laser.