Continuous-Wave Laser Emission of Pr: ${\rm LiYF}_{4}$ at 695.8 nm

We present a diode-pumped Pr: LiYF4 (Pr:YLF) laser at 695.8 nm by suppressing the higher gain transitions near 640, 670, 698, and 721 nm. With an InGaN laser diode as the pump source, the output power of the laser centered at 695.8 nm in σ polarization was up to 51 mW, corresponding to a slope efficiency of 12.6% and a threshold power of 229 mW with respect to absorbed pump power. To the best of our knowledge, this is the first Pr:YLF laser emitting at 695.8 nm in σ polarization.