Tunable quasi-cw two-micron lasing in diode-pumped crystals of mixed Tm3+-doped sodium — lanthanum — gadolinium molybdates and tungstates

Abstract

Two-micron lasing is obtained for the first time on the 3F4 → 3H6 transition of Tm3+ ions in diode-pumped crystals of mixed sodium — lanthanum — gadolinium tungstate Tm:NaLa1/2Gd1/2(WO4)2 (CTm = 3.6 at %) (3.6Tm : NLGW) and molybdate Tm:NaLa1/3Gd2/3(MoO4)2 (CTm = 4.8 at %) (4.8Tm : NLGM). For the 3.6Tm : NLGW crystal, the quasi-cw laser output power exceeded 200 mW and the slope efficiency (with respect to absorbed pump power) for the π- and σ-polarisations at wavelengths of 1908 and 1918 nm was 34% and 30%, respectively. The laser wavelength of this crystal was continuously tuned within the spectral range of 1860 — 1935 nm. For the 4.8Tm : NLGM crystal, the slope efficiency for the π- and σ-polarisations at wavelengths of 1910 and 1918 nm was 27% and 23%, respectively, and the laser wavelength was tunable within the spectral range of 1870 — 1950 nm.