Passively Q-switched Pr:YLF laser with a Co²⁺:MgAl₂O₄ saturable absorber

We report on a 2ω-OPSL-pumped passively Q-switched Pr³⁺:LiYF₄ laser operating at the wavelengths of 523, 607, and 640 nm. For this, we utilized a Co²⁺-doped MgAl₂O₄ (MALO) crystal as a saturable absorber in the visible range for the first time, to the best of our knowledge. In the green spectral region, the pulse duration was 210 ns with a pulse energy of 3.6 μJ and a repetition rate of 125 kHz. The minimum pulse duration of 87 ns at the highest pulse energy of 8.6 μJ was obtained at a repetition rate of 110 kHz at 607 nm. The highest Q-switched average laser power of 1.4 W was obtained at an absorbed continuous-wave pump power of 3.3 W with a slope efficiency of 47% at 640 nm. Absorption saturation measurements with Co:MALO were performed, and ground and excited state absorption cross sections in the visible spectral range were determined.