How fast are laser pulses from modern short pulse lasers?

Modern high intensity lasers based on chirped pulse amplification have pulse durations as short as 20 femtoseconds (20 x 10^-15 s).

The key to CPA is to avoid amplifying the short pulses directly in the laser amplifier, where the intensity would become so high that nonlinear effects would lead to damage in the amplifier. Instead, low energy (nJ) short pulses produced by a ultrafast laser oscillator (1, below) are dramatically stretched in time (2). This is done by stretching out the various colors of the pulse using gratings.