  Spatio-temporal instabilities are widespread phenomena resulting from
complexity and nonlinearity. In broad-area edge-emitting semiconductor lasers,
the nonlinear interactions of multiple spatial modes with the active medium can
result in filamentation and spatio-temporal chaos. These instabilities degrade
the laser performance and are extremely challenging to control. We demonstrate
a powerful approach to suppress spatio-temporal instabilities using
wave-chaotic or disordered cavities. The interference of many propagating waves
with random phases in such cavities disrupts the formation of self-organized
structures like filaments, resulting in stable lasing dynamics. Our method
provides a general and robust scheme to prevent the formation and growth of
nonlinear instabilities for a large variety of high-power lasers.
