Review of ultrashort pulse measurement: changing the basic ultrashort pulse experiment

Until recently, experiments in ultrashort pulse science have involved measuring the spectrum and autocorrelation of the input pulse(s) and only measuring the integrated energy or perhaps time-resolved energy of the output signal. These experiments ignored the information contained in the input and output pulse phases and intensity profiles. New pulse measurement techniques such as frequency-resolved optical grating, when combined with older techniques such as spectral interferometry, now allow the complete characterization of the pulses. These techniques allow measurements of the intensity, phase, and polarization state of ultrashort pulses as functions of time (or frequency) and space. These techniques work for wavelengths from the UV to the IR and for extremely weak pulses and very high power pulses. They also allow entirely new classes of experiments for measuring ultrafast phenomena. Now the phases and temporal profiles of the input pulses may be measured and controlled, and the intensity and phase of the output pulses can also be measured. These new measurement techniques have thus greatly increased the obtainable information in ultrafast experiments. This paper reviews current pulse measurement methods including frequency-resolved optical grating and spectral interferometry and describes how they are changing the way that ultrashort pulse experiments are performed.