Rare-earth-doped calcium niobium gallium garnets (Ca3Nb1.5Ga3.5O12, shortly CNGG) are disordered laser materials attractive for ultrashort pulse generation. We report on the crystal growth by the Czochralski method, spectroscopy and efficient laser operation of Yb3+,Na+ and Yb3+,Na+,Li+-codoped CNGG-type crystals. Their cubic structure is confirmed by X-ray diffraction and Raman spectroscopy. The absorption / stimulated-emission cross-sections and lifetime of Yb3+ are determined. Continuous-wave (CW) laser experiments are performed in a compact cavity using a 968-nm InGaAs pump laser diode. A 11.9 at.% Yb,Na:CNGG crystal generated 3.74 W at 1069.9 nm with a slope efficiency of 56.5%. Yb,Na:CNGG is promising for sub-100-fs mode-locked lasers at ~1 μm.
We demonstrate the laser performance of a gadolinium scandium gallium garnet (GSGG) single crystal with 10 at.% Yb3 + -doping concentration. In the case of continuous-wave operation, the laser wavelength was blueshifted in the range from 1067.1 to 1027.2 nm with increasing the transmission of the output coupler from 0.5% to 30%. The maximum output power produced was 3.2 W with 3% output transmission. By employing a Cr4 + : YAG crystal as the saturable absorber, a stable Q-switched laser beam with 21-ns pulse duration and 38-μJ single-pulse energy was achieved at a 20-kHz repetition rate. This laser crystal should be a promising candidate for nanosecond pulse generation especially in harsh environments, such as outer space, due to its wide absorption and emission spectral bandwidths and strong radiation resistance.