Diode-Pumped Laser Operation of Tb3+:LiLuF4 in the Green and Yellow Spectral Range

Here, a diode-pumped laser based on trivalent terbium (Tb3+) as the active ion is reported. Optical pumping of a Tb3+-doped lithium-lutetium-fluoride (LiLuF4) crystal with up to 200 mW from a diode laser emitting at a wavelength of 488.2 nm enables continuous-wave lasing directly in the green and in the yellow. At an emission wavelength of 542 nm, the laser reaches an output power of up to 43.8 mW with a high slope efficiency of 52% with respect to the absorbed pump power. The yellow laser at 587 nm exhibits a slope efficiency of 22% and the output power of 13.8 mW is only limited by the available pump power. Laser thresholds as low as 14 and 27 mW of absorbed pump power are observed for the green and yellow, respectively. The investigations toward further optimization of the laser performance reveal that highly Tb3+-doped materials are suitable for compact, efficient, and affordable diode-pumped solid-state lasers with direct emission in the visible spectral range. These results are of high relevance, as in particular for the yellow spectral range such systems are currently not available.