Evolution of The Pulse
Intensity changes with lengths of nanoseconds are amplified by the Kerr-lensing process and the pulselength further shrinks to achieve higher field strengths in the center of the pulse. This sharpening process is only limited by the bandwidth achievable with the laser material and the cavity-mirrors as well as the dispersion of the cavity. The shortest pulse achievable with a given spectrum is called the bandwidth-limited pulse.
Laser media for ultrashort pulses (e.g., Ti:Sapphire) Dispersion management with prism sequences. Chirped mirror technology allows to compensate timing mismatch of different wavelengths inside the cavity due to material dispersion while keeping the stability high and the losses low.
The Kerr effect leads to the Kerr-lens and Self-phase modulation at the same time. To a first approximation it is possible to consider them as independent effects.
Read more about this topic: Kerr-lens Modelocking, Modelocking
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