LAUSR

We report on the crystal growth, spectroscopy characterization and first laser operation of a new tetragonal disordered "mixed" calcium aluminate crystal, Tm:Ca(Gd,Lu)AlO4. The introduction of Lu3+ leads to an additional inhomogeneous broadening of Tm3+ absorption and emission spectra compared to the well-known Tm:CaGdAlO4. The maximum stimulated-emission cross-section for the 3F4 → 3H6 Tm3+ transition is 0.91 × 10-20 cm2 at 1813 nm for σ-polarization, and the emission bandwidth is more than 200 nm. A continuous-wave diode-pumped Tm:Ca(Gd,Lu)AlO4 laser generates 1.82 W at 1945 nm with a slope efficiency of 29%. Under Ti:Sapphire laser pumping, a continuous tuning of the laser wavelength from 1836 to 2083 nm (tuning range: 247 nm) is demonstrated. The Tm:Ca(Gd,Lu)AlO4 crystal is promising for tunable/femtosecond lasers at ~2 μm.