The measurement of ultrashort pulses: from simple laser pulses to unstable, ultracomplex, ultrabroadband, ultra weak light pulses

We review the state of the art of ultrashort-light-pulse measurement. Particularly, progress has been made in extending FROG to measuring unstable, ultracomplex, and ultrabroadband pulses (microstructure-fiber supercontinua); measuring ultraweak light pulses, which have random absolute phase and poor spatial coherence; and development of an ultracompact pulse-measurement device-GRENOUILLE, which yields not only intensity and phase, but also spatial chirp and pulse-front tilt.