Nonlinear dynamics inside femtosecond enhancement cavities

We have investigated the effect of intracavity nonlinear dynamics arising from enhanced peak powers of femtosecond pulses inside broad- bandwidth, dispersion-controlled, high-finesse optical cavities. We find that for chi((3)) nonlinearities, when a train of femtosecond pulses are maximally coupled into a cavity by active stabilization of its frequency comb to the corresponding linear resonances of a cavity, enhancement ceases when the peak nonlinear phase shift is sufficient to shift the cavity resonance frequencies by more than a cavity linewidth. In addition, we study and account for the complex spectral dynamics that result from chirping the input pulse and show excellent qualitative agreement with experimental results. (C) 2005 Optical Society of America.