Red Sm:KGd(WO 4 ) 2 laser at 649 nm

We report on the first laser operation of a Sm 3+ -doped monoclinic KGd(WO 4 ) 2 double tungstate crystal in the red spectral range. Pumped by a frequency-doubled optically pumped semiconductor laser (2 ω -OPSL) at 479.1 nm, the 0.8 at. % Sm:KGd(WO 4 ) 2 laser generated an output power up to 17.6 mW at 649.1 nm (the 4 G 5/2 → 6 H 9/2 transition) with a slope efficiency of 16.9%, a laser threshold down to 29 mW and a linear polarization. The laser exhibited a self-pulsing behavior, delivering µs-long pulses with a repetition rate of a few kHz. The polarized spectroscopic properties of Sm 3+ ions were determined as well.