Passively Q-switched 8.5-ns Pr3+:YLF laser at 640 nm

We report on short pulse generation from a passively Q-switched Pr3+:LiYF4 laser operating at 640 nm. By reducing the cavity length and utilizing Co:MgAl2O4 as the saturable absorber, we obtain the shortest pulse durations from any Q-switched Pr3+ laser. Under pumping with a frequency-doubled optically pumped semiconductor laser at a wavelength of 479.05 nm we realized (8.5 ± 1) ns long pulses at a repetition rate of 0.78 MHz from a 7.5 mm long cavity at an average output power of 1.0 W. In that case, the laser pulse energy and duration were 1.3 µJ and 8.5 ns, respectively. The highest pulse energy amounts to 1.8 µJ at a pulse peak power of 0.19 kW in 9.2 ns pulses at a repetition rate of 0.48 MHz.