Speaker
Description
Accurate characterization of ultrashort laser pulses is essential for the development and optimization of modern ultrafast sources and for their use in increasingly demanding applications. The dispersion scan (d-scan)1 technique was introduced as a self-referenced, non-interferometric method for the complete temporal characterization of few-cycle pulses. The technique is based on introducing a controlled amount of dispersion into the pulse and recording the resulting second-harmonic spectrum as a function of the applied dispersion. The acquisition of this two-dimensional d-scan trace encodes the information required to retrieve the spectral phase and temporal profile of the pulse.
Since its introduction, d-scan has evolved into a versatile family of approaches that can address very different laser sources. This evolution encompasses different nonlinear processes, dispersion-control schemes and acquisition geometries that extend the technique across a broad range of wavelengths and pulse durations. The single-beam nature of d-scan also greatly simplifies temporal pulse characterization directly at the focus, where the pulse interacts with a target or sample3. These developments include the characterization of few-cycle and sub-10-fs pulses, extension towards more challenging spectral regions, and single-shot implementations for low-repetition-rate4,5, unstable or non-repetitive sources.
Temporal characterization alone, however, does not provide a complete description of ultrashort laser beams. Spatial variations of the spectral amplitude and phase can produce spatio-temporal couplings that strongly affect the pulse at focus and its interaction with matter. Complementary approaches for spatio-temporal characterization are therefore also considered, in particular the ICE2 (Integral Characterisation Engine) system, which enables spatially resolved spectral-phase measurements and the identification of relevant spatio-temporal couplings.
The different d-scan implementations reflect the evolution of ultrafast laser technology, extending from the measurement of few-cycle temporal waveforms to the characterization of multi-cycle laser systems. Equally important is the spatio-temporal characterization of ultrafast laser systems, providing the information required to control the pulses in the most demanding applications. Ultimately, ultrafast metrology is not only about measuring pulses, but about providing the information needed to control the light that actually drives the experiment.