"Mixed" Tm:Ca(Gd,Lu)AlO 4 - a novel crystal for tunable and mode-locked 2 µm lasers

• Published in: Optics express Vol. 27; no. 7; p. 9987
• Main Authors: Pan, Zhongben, Loiko, Pavel, Serres, Josep Maria, Kifle, Esrom, Yuan, Hualei, Dai, Xiaojun, Cai, Huaqiang, Wang, Yicheng, Zhao, Yongguang, Aguiló, Magdalena, Díaz, Francesc, Griebner, Uwe, Petrov, Valentin, Mateos, Xavier
• Format: Journal Article
• Language: English
• Published: United States 01.04.2019
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.27.009987

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)AlO . The introduction of Lu leads to an additional inhomogeneous broadening of Tm absorption and emission spectra compared to the well-known Tm:CaGdAlO . The maximum stimulated-emission cross-section for the F → H Tm transition is 0.91 × 10 cm at 1813 nm for σ-polarization, and the emission bandwidth is more than 200 nm. A continuous-wave diode-pumped Tm:Ca(Gd,Lu)AlO 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)AlO crystal is promising for tunable/femtosecond lasers at ~2 μm.