Few-cycle mid-infrared pulse full characterization in single shot

We build a frequency resolved optical gating (FROG) setup based on the second harmonic generation (SHG) FROG to characterize the mid-infrared (MIR) few-cycle laser pulse in single shot basis. Considering the extremely wide bandwidth; we use 20-mu m-thick BBO crystal as the nonlinear medium; and correct the spectral response with the frequency summing efficiency. Spatial splitting is adopted to avoid additional material dispersion. In combination with a 4f imaging; this configuration enables the setup to run in single shot. With the central wavelength of 1.8 mu m; the measured pulse has a duration of 9.3 fs; which corresponds to about 1.5 cycles.