Ti-Doped β-Ga₂O₃: A Promising Material for Ultrafast and Tunable Lasers

Abstract

As we know, Ti3+:Al2O3 is a very famous crystal for ultrafast and tunable lasers. However, it also has disadvantages including small segregation coefficient and short fluorescence lifetime of Ti3+. For comparison, Ti-doped β-Ga2O3 (Ti3+:β-Ga2O3) single crystals with good spectral properties have been designed and grown successfully by edge-defined film-fed growth method with larger segregation coefficient and longer fluorescence lifetime. The segregation coefficient of Ti3+ ions in the Ti3+:β-Ga2O3 crystal was calculated to be 0.49, which was much larger than that in Ti3+:Al2O3 (0.2). The thermal conductivity of Ti3+:β-Ga2O3 crystal was measured to be 24.7 W/mK along the ⟨010⟩ direction at room temperature, which is very attractive as a laser crystal. Furthermore, the polarized absorption spectra and fluorescence spectra of Ti3+:β-Ga2O3 were measured and analyzed. The full width at half-maximum of the emission peak was as large as 140 nm. The fluorescence lifetime was up to 176 ± 5 μs, which was about 50 times longer than that of Ti3+:Al2O3. All the properties indicate that Ti3+:β-Ga2O3 is a potential material for ultrafast and tunable laser applications.