Self-similarities in the frequency-amplitude space of a loss-modulated   CO$_2$ laser
  We show the standard two-level continuous-time model of loss-modulated CO$_2$ lasers to display the same regular network of self-similar stability islands known so far to be typically present only in discrete-time models based on mappings. For class B laser models our results suggest that, more than just convenient surrogates, discrete mappings in fact could be isomorphic to continuous flows. 
Cristian Bonatto, Jean Claude Garreau, Jason A.C. Gallas