Pulses in the two-cycle regime from a SESAM-assisted KLM Ti:sapphire laser and sub 10-fs pulse characterization

Summary form only given. Proper measurement of sub-10-fs pulses is still controversial and challenging. The duration of world record ultrashort optical pulses has previously been estimated from interferometric autocorrelation (IAC) traces. Other techniques, such as spectral phase interferometry for direct electric-field reconstruction (SPIDER) and frequency-resolved optical gating (FROG) have been developed that retrieve both amplitude and phase of the pulse. We discuss the limitations of SPIDER, FROG, and IAC for ultrashort pulses. Pulse durations can be significantly underestimated by fitting parameters of an ideal sech/sup 2/-soliton to the IAC.