Diode-pumped continuous-wave, quasi-continuous-wave, and Q-switched laser operation of Yb3+,Tm3+: YLiF4 at 1.5 and 2.3 μm

We report continuous-wave (cw), quasi-cw and $Q$ -switched laser oscillation of ${\mathrm{Yb}}^{\mathrm{3+}}{\mathrm{,Tm}}^{\mathrm{3+}}$ -doped ${\mathrm{YLiF}}_4$ at 1.5 and $\text{2.3\hspace{0.5em}μ}\mathrm{m}.$ Maximum cw output powers of 300 mW at 1.5 $\mu \mathrm{m}$ and 450 mW at $\text{2.3\hspace{0.5em}μ}\mathrm{m}$ have been obtained. Quasi-cw excitation revealed 20 mJ pulses at $\text{1.5\hspace{0.5em}μ}\mathrm{m}.$ The cw pumped $\text{1.5\hspace{0.5em}μ}\mathrm{m}$ laser was passively $Q$ -switched using a ${\mathrm{U:CaF}}_2$ crystal as saturable absorber with a repetition rate of 65 kHz and a pulsewidth of 800 ns. An average output power of 19 mW was achieved. The dynamics of the system was simulated using a rate equation model.