The present paper analyses features of super-continuum generated from pulsed and CW excitation. It has been shown
that generation mechanisms and many properties of super-continuum produced with CW excitation are cardinally
different from those of super-continuum generated by pulsed excitation. On the other hand, different applications pose
different, and often opposite requirements to the super-continuum, which cannot be satisfied within a single universal technique of super-continuum generation. In this connection, we have analyzed pulsed and CW schemes of super-continuum generators and conditions which should be fulfilled in order to achieve optimal super-continuum parameters required in most typical super-continuum applications (metrology, tomography, spectroscopy, communications). In particular, we consider a special regime of super-continuum generation, where an amplitude-modulated CW pump breaks up into periodic sequence of ultra-short pulses under the action of induced modulation instability. In the work we have studied for the first time the effect of noise (spontaneous emission) on this break-up and determined conditions for depth and frequency of initial modulation needed for this process both numerically and analytically (in the approximation of slightly intensity modulated CW pump radiation).