Ultra-broad absorption band of a Dy3+-doped Gd3Sc2Al3O12 garnet crystal at around 450 nm: a potential crystal for InGaN LD-pumped all-solid-state yellow lasers

Abstract

In this study, for the first time, a high-quality 2 at% Dy³⁺-doped Gd₃Sc₂Al₃O₁₂ (Dy:GSAG) single crystal was grown successfully by the Czochralski method. Spectroscopic properties of the crystal were investigated in detail. The crystal shows an ultra-broad absorption band at around 447 nm with FWHM of 31 nm. The absorption cross-section at 447 nm and emission cross-section at 582 nm are evaluated to be as high as 0.307 × 10⁻²⁰ cm² and 0.390 × 10⁻²⁰ cm², respectively. Three intensity parameters Ω_t (t = 2, 4, and 6) as well as spectral parameters were obtained based on the Judd–Ofelt calculation. The fluorescence quantum efficiency η for the ⁴F_9/2 level was evaluated to be 77.2%, which was much higher than that of the Dy:YAG crystal. In addition, evident yellow light emitting and white light emission were directly observed in the crystal under 450 nm and 355 nm horizontal and vertical laser excitation, respectively. The results indicate that the Dy:GSAG crystal could be a potential candidate for all-solid-state yellow lasers at 582 nm pumped by a blue InGaN laser-diode.