High-sensitivity, simple frequency-resolved-optical-gating device

We introduce a practical self-referenced device for the complete temporal intensity-and-phase measurement of few-femtojoule-level fs and ps pulses based on the simple version of frequency-resolved-optical gating, called GRENOUILLE. We replace the usual crossed-beam line-focus geometry with a point-focus near-collinear-beam geometry and a traditional delay line that allows a longer path length in the nonlinear medium, yielding greater sensitivity. As an initial demonstration of the device, we measured moderately complex pulses at energies as weak as 24 fJ with high signal-to-noise ratio. We confirmed the results measured using our technique to that of a standard GRENOUILLE and a high-resolution spectrometer.