Growth, thermal and spectral properties, and laser performance of Tm3+:CNGS crystal

New composite functional crystals of Tm3+:Ca3NbGa3Si2O14 (Tm3+:CNGS) were successfully grown by the Czochralski (CZ) method. The structural, thermal and spectral properties of Tm3+:CNGS crystals were investigated. The laser output of a Tm3+:CNGS crystal in the 2 μm band was studied for the first time. The results showed that Tm3+:CNGS achieved a maximum output of 740 mW at a pump power of 5 W, and the slope efficiency and light-to-light conversion efficiency reached 17.07% and 14%, respectively. The thermal properties are presented, and the coefficient of linear thermal expansion of Tm3+:CNGS increased with respect to that of a pure CNGS crystal in the Z-axis direction, which may have been due to a change in the bulk density of the oxygen dodecahedron in the X-axis direction after partial replacement of the rare earth ions. In addition, the specific heat, thermal diffusivity, and thermal conductivity of Tm3+:CNGS slightly increased in comparison with those of the undoped CNGS crystal. The absorption spectra of Tm3+:CNGS had a strong peak at 793 nm, and its absorption cross-section was 5.01 × 10−21 cm2. The fluorescence spectra at room temperature had a full width at half maximum (FWHM) of 164 nm and a peak wavelength of 1888 nm, and the lifetime of the 3F4 upper energy level of the laser was 2.345 ms. Its good thermal properties, large emission linewidth, and ease of growth indicate that a Tm3+:CNGS single crystal could have the potential to be a good laser gain medium.