614 Selected Applications
enables the formation and propagation of solitons propagating at different veloc-
ities. As these higher-order solitons break up, parametric four wave mixing
generates frequencies at wavelengths shorter than the zero dispersion wavelength,
eventually leading to an intense blue radiation coexisting with a broad infrared
supercontinuum [104]. One conclusion was that special fibers can only be used
to extend the frequency comb of sub-150-fs pulse trains.
13.4.2. Locking of fs Lasers to Stable
Reference Cavities
Earlier stabilization experiments with mode-locked lasers often used short
Fabry–Perot etalons to stabilize the average position of the comb, directly
employing the techniques developed for single-mode lasers [105, 106]. ...