We report on the passive Q-switching laser performance of Yb:LaCa 4 O(BO 3 ) 3 crystal with Cr 4+ :YAG or two-dimensional (2D) MoS 2 acting as a saturable absorber. With Cr 4+ :YAG, a pulsed output power of 3.8 W was produced at 71 kHz with a slope efficiency of 49%, whereas at a lower repetition rate, the average pulse energy achieved could reach 250 µJ; the shortest duration and peak power were respectively 17 ns and 14.7 kW. For passive Q-switching with 2D MoS 2 , 1.61 W of pulsed output power was achieved at 395 kHz; the resulting pulse energy, duration, and peak power were 4.1 µJ, 220 ns, and 18.6 W, respectively.