At the threshold of distributed Kerr-lens mode-locking in a Cr:ZnS waveguide laser

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.