Spectroscopy of solid-solution transparent sesquioxide laser ceramic Tm:LuYO<sub>3</sub>
Kirill Eremeev, Pavel Loiko, Alain Braud, Patrice Camy, Jian Zhang, Xiaodong Xu, Yongguang Zhao, Peng Liu, Stanislav Balabanov, Е. Б. Дунина, А. А. Корниенко, Liudmila Fomicheva, Xavier Mateos, Uwe Griebner, Valentin Petrov, Li Wang, Weidong Chen
Abstract
We report on a detailed spectroscopic study of a Tm 3+ -doped transparent sesquioxide ceramic based on a solid-solution (lutetia – yttria, LuYO 3 ) composition. The ceramic was fabricated using commercial oxide powders by hot isostatic pressing at 1600°C for 3 h at 190 MPa argon pressure. The most intense Raman peak in Tm:LuYO 3 at 385.4 cm -1 takes an intermediate position between those for the parent compounds and is notably broadened (linewidth: 12.8 cm -1 ). The transition intensities of Tm 3+ ions were calculated using the Judd-Ofelt theory; the intensity parameters are Ω 2 = 2.537, Ω 4 = 1.156 and Ω 6 = 0.939 [10 20 cm 2 ]. For the 3 F 4 → 3 H 6 transition, the stimulated-emission cross-section amounts to 0.27 × 10 −20 cm 2 at 2059nm and the reabsorption-free luminescence lifetime is 3.47 ms (the 3 F 4 radiative lifetime is 3.85 ± 0.1 ms). The Tm 3+ ions in the ceramic exhibit long-wave multiphonon-assisted emission extending up to at least 2.35 µm; a phonon sideband at 2.23 µm is observed and explained by coupling between electronic transitions and the dominant Raman mode of the sesquioxides. Low temperature (12 K) spectroscopy reveals a significant inhomogeneous spectral broadening confirming formation of a substitutional solid-solution. The mixed ceramic is promising for ultrashort pulse generation at >2 µm.