Watt-level diode-pumped continuous-wave Pr:LiYF4 laser at 670 nm and simultaneous dual-wavelength operation at 639 and 670 nm

We report on blue-diode-pumped continuous-wave Pr:LiYF4 (YLF) visible lasers involving a less investigated 670 nm laser emission. In the free-running regime, a simultaneous dual-wavelength operation at 670 and 639 nm is achieved with a maximum output power of 1.67 W and a slope efficiency of 20.4%. Using a Y3Al5O12 (YAG) plate as an intracavity etalon, we have suppressed the 639 nm emission, and then a single-wavelength laser at 670 nm has been achieved with a maximum output power of 0.96 W and slope efficiency of 12.7%. The directly generated 670 nm laser source from Pr:YLF crystal with watt-level output power has advantages over diode laser or frequency-doubled Nd:YVO4 lasers operating at a similar laser wavelength, which could be used in biomedical technologies.