Use of a LiF colour centre laser for pumping an Yb:YAG active medium

An Yb:YAG laser crystal containing 20% of Yb was pumped by a F₂⁺:LiF colour centre laser emitting in the spectral range from 0.89 to 0.95 μm. We managed to pump 10% of a total amount of Yb ions to the ²F_5/2 metastable level of ytterbium in small volumes of the optically dense Yb:YAG laser crystal, which corresponds to the energy density stored in the crystal equal to 30 J cm^-3. Nanosecond pulses were generated at transitions between the Stark components of the ²F_5/2 and ²F_7/2 levels of Yb³⁺ ions at the wavelengths near 1.03 and 1.05 μm. The possibility of using Yb:YAG crystals and ceramics in high-power laser drivers in laser fusion experiments is discussed.