Heat-induced wavelength-switchable high-power CW orange Pr3+: YLF lasers

Pr3+:YLF crystal has been demonstrated as a successful laser gain medium in the visible region. However, the 604-nm laser based on this crystal is limited in power due to the intrinsic reabsorption in the orange region. We propose a laser diode (LD) pumped continuous-wave (CW) 604-nm laser based on a lowly-doped Pr3+:YLF crystal. A maximum output power of 3.28 W with a total slope efficiency of 34.2% is achieved at 604 nm. The slope efficiency increases to 43.0% under high-power pumping conditions. To the best of our knowledge, the output power of the 604-nm laser we achieved is the highest to date and no output power saturation is observed. Besides, dual-wavelength operations at 604 and 607 nm are achieved by tuning the thermal lensing effects of the crystal, without any additional wavelength-selection elements. The dual-wavelength laser at 604 and 607 nm with a maximum output power of 3.30 W (highest to date as well) is obtained by this approach. Since no extra intracavity losses are introduced by intracavity wavelength-selection elements, the method we proposed will be promising to obtain high-power wavelength-switchable lasers.