Spectral anomalies and stability of chirped-pulse oscillators

Comprehensive numerical analysis of chirped-solitary-pulse stability in the positive-dispersion regime is presented. It is found that such a regime allowing generation of femtosecond pulses with energy above the microjoule level directly from a mode-locked oscillator is unstable against long-period pulsations. Pulsations are caused by the internal modes of solitary pulse and result in both symmetrical and asymmetrical perturbations of the pulse spectrum. This reduces a region of pulse stability and its coherence.