Frequency and peak discontinuities in self-pulsations of a CO2 laser with feedback

We show that self-pulsations observed in a CO2 laser with feedback display two types of recurrent period discontinuities when control parameters are changed. Periodic self-pulsations emerge organized in wide adjacent phases in which oscillations differ by a constant number of peaks in their period. The number of peaks increases through characteristic pulse deformations of the signal that we describe in detail. The passage across the boundaries delimiting adjacent phases is abrupt and not mediated by windows of chaos. In addition, we provide an explicit criterion for locating the discontinuity boundaries between adjacent phases.