We report on blue-diode-pumped continuous-wave
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(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
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(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
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lasers operating at a similar laser wavelength, which could be used in biomedical technologies.