  We demonstrate feasibility of spatiotemporal mode-locking in a mid-IR Cr:ZnS
waveguide laser based on the nonlinear spatial mode coupling. The experiment
shows efficient power scaling with the excitation of intra-mode beatings,
causing a pronounced Q-switching which could cause a nonlinear mode-coupling.
We suggest that a particularly high nonlinearity in Cr:ZnS combined with
multimode waveguide leads to a soft aperture induced by a pump beam. The latter
provides an effective spatial mode control in a nonlinear multimode waveguide
and, thereby, opening the way to the birth of a spatiotemporal dissipative
soliton, or light bullet, formation. Thus, forming the basis for the future
distributed Kerr-Lens Mode Locking in the energy-scalable solid-state waveguide
(or yet unrealized fiber) laser.

Optics