In this work, we demonstrate the sensitivity of the frequency-resolved optical switching (FROSt) technique to detect a small amount of spectral phase shift for the precise characterization of ultrashort laser pulses. We characterized fs pulses centered at 1.75 µm that are spectrally broadened up to 700 nm of bandwidth in a hollow-core fiber and subsequently compressed down to 2.3 optical cycle duration by propagation in the air at atmospheric pressure. By inserting thin fused silica windows of different thicknesses in the beam path, we accurately retrieve group delay dispersion (GDD) variations as small as 10 fs2. Such GDD variations correspond to a change of the pulse duration of only 0.2 fs for a Fourier transform limited 2-cycle pulse at 1.75 µm (i.e., 11.8 fs). The capability to measure such tiny temporal variations thus demonstrates that the FROSt technique has sufficient sensitivity to precisely characterize single-cycle pulses.

We present advanced features of the frequency resolved optical switching technique: (i) temporal characterization of an IR supercontinuum, (ii) a high precision on group delay dispersion, (iii) characterization of pulses independently of their polarization direction.

We present advanced features of the frequency resolved optical switching technique: (i) temporal characterization of an IR supercontinuum, (ii) a high precision on group delay dispersion, (iii) characterization of pulses independently of their polarization direction.

We experimentally demonstrate the formation of multidimensional solitary states (MDSS) in N2O-filled hollow-core fiber (HCF), driven by ultraviolet (UV) sub-picosecond pulses.