Spatial rogue waves in the actively Q-switched Nd:YAG laser under low Kerr nonlinearity

We report the generation of spatial rogue waves in an actively Q-switched Nd:YAG laser. We observed that spatial rogue waves can emerge when the laser operates in a low-power regime below the self-focusing limit, while the lasing takes place at a large number of high-order transverse modes. These results suggest that the main mechanism leading to rogue waves generation is the modal overlap while large Kerr nonlinearity in the cavity is not a necessary factor in the process of spatial rogue waves formation. We have also investigated the spatio-temporal and coherence properties of the observed rogue waves.