Simulation of spatial rogue waves in actively Q-switched solid-state laser with transverse mode locking

We report the generation of spatial rogue waves in the actively Q-switched Nd:YAG laser with several transverse modes and negligible nonlinear effects in the cavity. We discuss a basic theoretical model that is able to reproduce the experimental observations of spatial rogue waves in the output Q-switched pulses as a result of the coherent superposition of transverse modes. The simulated rogue wave statistics depends on the configuration of the lasing modes and take a more pronounced L-shaped form in the case of highly anisotropic mode distribution and reduced frequency spacing between the modes. For larger frequency spacing between the modes, the mode-locking effects result in the periodic dynamics of the transverse beam profile and formation of spatio-temporal rogue waves. These results indicate that transverse mode-locking and spatial symmetry breaking through anisotropy in the mode configuration represent factors responsible for spatial rogue wave emergence in multimode lasers with low nonlinearity.