Demonstration of Self-Starting Nonlinear Mode Locking in Random Lasers

In ultrafast multimode lasers, mode locking is implemented by means of saturable absorbers or modulators, allowing for very short pulses. This occurs because nonlinear interactions modes with well equispaced frequencies. Though theory predicts that, in the absence any device, would occur random this has never been demonstrated so far. Through analysis correlations we provide clear evidence coupling lasers. The behavior multiresonance intensity tested against frequency matching condition equivalent to one underlying phase ordered Nontrivially large are clearly observed spatially overlapping resonances that sensitively depend on be satisfied, eventually demonstrating occurrence mode-locked coupling. first example, our knowledge, an experimental realization self-starting many new developments design and use nanostructured devices.