Time-domain interferometry for direct electric field reconstruction of mid-infrared femtosecond pulses

Mid-infrared ultrashort pulses of 9.2-μm center wavelength are characterized in both amplitude and phase. This is achieved by use of a variant of spectral phase interferometry for direct electric field reconstruction in which spectral interferometry has been replaced with time-domain interferometry, a technique that is well suited for infrared pulses. The setup permits simultaneous recording of the second-order interferometric autocorrelation, thus providing an independent check on the retrieved spectral phase.