Passive Q-switching at 1.54 μm of an Er–Yb: GdCa₄O(BO₃)₃ laser with a Co²⁺: MgAl₂O₄ saturable absorber

We report, for the first time to our knowledge, efficient passive Q-switching of the 1.54-mu m laser transition in an Er-Yb-doped crystalline medium. The laser configuration is a compact microchip design that is suitable for a range of practical applications such as range finding and lidar. The slope efficiency of 11.6%, pulse duration of 5-6 ns and average output power of 88 mW are all comparable with standard Er-Yb:glass lasers.