Ultrashort Laser Pulse Phenomena, 2nd Edition

Introduction 291

favor pulsed over continuous radiation. The problem with the frequency domain

picture is the difficulty to treat the various processes in the laser including the

coupling between the large number of modes to predict the pulse parameters

M, E

m

, v

m

, and φ

0

. Recall that the mode frequencies v

m

are not given by the dis-

persion of the cold cavity, cf. Eq. (5.7), but establish themselves in the process

of mode-locking. Therefore the simple picture presented in the beginning of this

chapter can only serve as a qualitative description of the mode-locking process.

We have seen in the previous section that the frequency domain picture,

in which all longitudinal modes within the gain bandwidth oscillate in phase,

is an oversimplification. The