Characterization of the spatiotemporal evolution of ultrashort optical pulses using FROG holography

We propose holographically recorded frequency-resolved-optical-gating (FROG) measurement for probing the evolution of ultrashort optical pulses at multiple locations. As a proof-of-concept demonstration of our method, we record holographic FROG traces at five axial locations as we traverse through the focus of an objective lens along its axis using BaTiO3 micro-cluster as the nonlinear medium and retrieve the amplitude and phase of the ultrashort pulse at each location. Moreover, the group delay of the pulse retrieved numerically using FROG holography is used to compute the separation between the five locations which agree well with the experimentally measured distances. This study suggests that FROG holography can be used to remove the ambiguity regarding arbitrary constant phase and arbitrary temporal shift in the retrieved pulse at each location (upto to an overall constant phase).