Multiple-reflections single-shot dispersion scan for fast ultrashort-pulse measurements

A single-shot non-interferometric ultrashort-pulse measurement method based on the dispersion scan (d-scan) technique with a substantially extended time span for the pulses to be measured is presented. While single-shot d-scan is typically used for rather short femtosecond pulses, the presented multiple-reflections d-scan (MR d-scan) technique allows measurement of both short and long femtosecond pulses. Single-shot d-scan is currently limited to pulses with a maximum duration of 60 fs using a chromatic dispersion, i.e., a group delay dispersion (GDD) of 4400 fs² at 840 nm provided by customized random nonlinear crystals. MR d-scan achieves a GDD of 31100 fs² at 820 nm in this work, but can generally achieve an increase in GDD of up to two orders of magnitude. MR d-scan works with commonly available output couplers, does not rely on a homogeneous, precisely imaged beam profile and has an in-line configuration. As an example, long femtosecond double pulses are measured and reconstructed.