Fig. 1. Fluorescence spectrum of the Nd:GdLuAG crystal at room temperature. Inset: Fine spectrum of the F43/2→I413/2 transition.

Fig. 2. Schematic diagram of the experimental setup, and the transmission of the different output couplers used in this experiment.

Fig. 3. (a) Output power as a function of the absorbed pump power. (b) The calculated initial laser thresholds at different wavelengths, and the experimental results at 1338 nm.

Fig. 4. Laser spectra at different absorbed pump powers when T=3.4%: (a) Pab=0.8  W. (b) Pab=3.2  W. (c) Pab=6.8  W. (d) Pab=9.42  W.

Fig. 5. Characterization of the passive Q-switching laser. (a) Average output power versus the absorbed pump power. (b) Pulse width as a function of the absorbed pump power; inset: pulse profile of 21.8 ns. (c) Pulse energy versus the absorbed pump power. (d) Laser spectrum of the passive Q-switched dual-wavelength laser at the absorbed pump power of 9.42 W; inset: the pulse trains at 14.8 kHz.

Fig. 6. Initial population inversion density versus the initial transmittance of the absorber and the output coupler (left). Total population inversion density at the different couplers (right).