Tunable room-temperature cw laser action in Cr3+: GdScAl-garnet

We report, for the first time, cw room temperature laser action of Cr³⁺:Gd₃Sc₂Al₃O₁₂. These crystals show a strong band fluorescence due to the ${}^4\text{T}{}_2\text{→}{}^4\text{A}{}_2$ transition with a lifetime of 150 μs. Laser pumping in the blue and red spectral range yields a minimum threshold of 170 mW and slope efficiencies up to 18.5%. The emission of the free running laser is centered at 784 nm with a FWHW of 5 nm. The extension of the Ga-garnets to Al-garnets as suitable host lattices for Cr³⁺ reveals the variety of garnet-structured crystals having an appropriate ligand field for continuously tunable laser operation.