Spectroscopy and Lasing of Yb-Doped ${hbox {NaY}}{({hbox {WO}}_{4})}_{2}$: Tunable and Femtosecond Mode-Locked Laser Operation

Tetragonal (space group f4 macr) single crystals of NaY(WO₄)₂ doped with Yb to a density of 4.52 times 10²⁰ cm^-3 have been employed as laser active materials for the 1-mum spectral range, operating at room temperature. Using Ti:sapphire laser pumping, slope efficiencies as high as 74.6% were achieved without special cooling for the pi-polarization. The Yb-laser was continuously tunable from 1003.7 to 1073.0 nm with a birefringent filter. Pulses as short as 53 fs were obtained at 1035 nm by SESAM passive mode-locking with intracavity dispersion compensation and additional extracavity pulse compression using analogous prism pairs. Experimental data on the spectroscopic properties of Yb³⁺ in the 5-300 K temperature range and the room temperature optical properties of this novel Yb-host is also presented.