Amplitude and phase measurement of mid-infrared femtosecond pulses using XFROG

Summary form only given.Frequency-resolved optical gating (FROG) has been shown to be a versatile technique for the measurement of ultrashort pulses across a wide range of wavelengths, and common approaches rely on using a detector array to record the spectrum of the second-harmonic autocorrelation signal of a pulse. In this work we demonstrate a technique which generates cross-FROG (XFROG) trace by sum-frequency mixing a mid-infrared pulse with a time-delayed near-infrared pulse. By using an adapted version of the principal components generalised projection retrieval algorithms we have been able to characterise both pulses in amplitude and phase.