Dy³⁺ and Tb³⁺ codoped mixed garnet crystals with a high-disorder structure for promising efficient InGaN laser-diode pumped yellow lasers

Two distinct compositions of mixed garnet crystals, codoped with Dy-3+ and Tb3+ ions, were grown using the Czochralski method. The structures and thermal properties of these crystals were thoroughly examined, and the influence of the doped ions on their structure and thermal properties was analyzed. Additionally, a straightforward and reliable method was introduced for accurately determining the specific heat and thermal diffusivity of garnet crystals across a wide temperature range, extending from room temperature to elevated temperatures. The absorption properties of the crystals were investigated, and their bandgap energies were determined using the Tauc formula. The relationship between the bandgap energy of garnet crystals and the radius of cations corroborates Yadav's prediction. Furthermore, the emission characteristics of the crystals under blue, UV, and VUV excitation were thoroughly studied. A proposed mechanism for energy transfer between Dy3+ and Tb3+ ions in the mixed garnet crystals was elucidated based on the absorption and emission characterization. The results indicate that the mixed garnet crystals exhibit distinct advantages for the development of blue laser diode pumped yellow lasers. Overall, this study provides valuable insights into the structural, thermal, optical, and energy transfer properties of mixed garnet crystals, highlighting their potential applications in all solid-state yellow laser technology.