Single-Shot, Spatio-Temporal Metrology of Relativistic Plasma Optics

Ultrahigh peak power femtosecond laser pulses create extreme states of matterthat are currently being probed with great interest. Plasma optics have beenproposed for shaping and amplifying high-power pulses, but they are subject tohuge modulations and fluctuations due to the very nature of excitation at highintensities. Multidimensional characterization (spatial and temporal) ofrelativistic plasma dynamics is therefore crucial to understand thespatio-temporal structure of intense femtosecond pulses shaped by plasmaoptics. This is, however, extremely difficult to achieve, particularly at thelow repetition rates typical at 100s terawatt to petawatt powers. Here, wepresent a single-shot, three-dimensional (3D) spatio-temporal andspatio-spectral measurement of such pulses based on spectral interferometry. Wereconstruct the 3D temporal structure of the laser pulse simultaneouslyresolving the complex plasma dynamics. We demonstrate our method by measuringthe sub-picosecond evolution of relativistic solid-density plasmas. Ourmeasurements reveal that different spatial regions of the plasma surface movedifferently yet exhibit a collective behavior globally. This all-opticalmeasurement technique captures 3D spatio-temporal effects within pulses withultrahigh peak powers, all in a single shot, enabling further progress inultrahigh-intensity laser and plasma technologies.