Diode-pumped orange Sm:LiYF₄ lasers emitting at 605 nm

We report on the first visible orange samarium laser directly pumped by a blue 465-nm GaN semiconductor laser diode. The diode-pumped continuous-wave Sm:LiYF₄ laser delivers 23.9 mW at 605 nm (⁴G_5/2 → ⁶H_7/2 transition) with a slope efficiency of 9.4%, a laser threshold of 385 mW and a linear polarization (π). We investigate the impact of pump beam quality on laser performance and revisit the polarized spectroscopic properties of Sm³⁺ ions in the LiYF₄ crystal. The stimulated-emission cross-section σ_SE amounts to 1.27 × 10^-20 cm² at 604.8 nm for π-polarized light, and the luminescence lifetime of the ⁴G_5/2 level is 4.02 ms for 1.1 at.% Sm-doping. Our work represents a proof-of-principle for compact low-threshold diode-pumped orange and red samarium lasers.