OPERATION OF A FEMTOSECOND TI-SAPPHIRE SOLITARY LASER IN THE VICINITY OF ZERO GROUP-DELAY DISPERSION

We report the operating characteristics of a self-mode-locked Ti:sapphire solitary laser at reduced group-delay dispersion. The generation of almost-equal-to 12.3 fs near-sech2 optical pulses at 775 nm is reported, together with experimental evidence for the dominant role of third-order dispersion (TOD) as a limiting factor to pulse shortening in the oscillator. At reduced second-order dispersion excessive residual TOD is shown to lead to dispersive wave generation, and the position of the dispersive resonance is used to determine the ratio of the net second- and third-order intracavity dispersions. Since the magnitude of TOD rapidly decreases with increasing wavelength in prism-pair dispersion-compensated resonators, the oscillator presented has the potential for producing sub-10-fs pulses in the 800-nm wavelength region.