  The mode dynamics of a random laser is investigated in experiment and theory.
The laser consists of a ZnCdO/ZnO multiple quantum well with air-holes that
provide the necessary feedback. Time-resolved measurements reveal multimode
spectra with individually developing features but no variation from shot to
shot. These findings are qualitatively reproduced with a model that exploits
the specifics of a dilute system of weak scatterers and can be interpreted in
terms of a lasing network. Introducing the phase-sensitive node coherence
reveals new aspects of the self-organization of the laser field. Lasing is
carried by connected links between a subset of scatterers, the fields on which
are oscillating coherently in phase. In addition, perturbing feedback with
possibly unfitting phases from frustrated other scatterers is suppressed by
destructive superposition. We believe that our findings are representative at
least for weakly scattering random lasers. A generalization to random laser
with dense and strong scatterers seems to be possible when using a more complex
scattering theory for this case.
