Ultrafast evolution of electric fields from high-intensity laser-matter interactions

R Pompili,M Botton,M Ferrario,A Cianchi,M Petrarca,E Schleifer,M P Anania,A Zigler,F Bisesto,Z Henis,A Curcio,M Galletti,E Chiadroni

doi:10.1038/s41598-018-21711-4

Abstract

The interaction of high-power ultra-short lasers with materials offers fascinating wealth of transient phenomena which are in the core of novel scientific research. Deciphering its evolution is a complicated task that strongly depends on the details of the early phase of the interaction, which acts as complex initial conditions. The entire process, moreover, is difficult to probe since it develops close to target on the sub-picosecond timescale and ends after some picoseconds. Here we present experimental results related to the fields and charges generated by the interaction of an ultra-short high-intensity laser with metallic targets. The temporal evolution of the interaction is probed with a novel femtosecond resolution diagnostics that enables the differentiation of the contribution by the high-energy forerunner electrons and the radiated electromagnetic pulses generated by the currents of the remaining charges on the target surface. Our results provide a snapshot of huge pulses, up to 0.6 teravolt per meter, emitted with multi-megaelectronvolt electron bunches with sub-picosecond duration and are able to explore the processes involved in laser-matter interactions at the femtosecond timescale.

Highlights

Multi-Terawatt laser pulses with femtosecond duration have opened new horizons in research of nonlinear transient phenomena like astrophysics in laboratory[1,2], particle acceleration[3,4,5], material science[6,7], surface phenomena[8], nuclear[9] and medical physics[10,11]
The temporal diagnostics is based on the EOS, i.e. on the electro-optic effect induced into a nonlinear crystal by an externally applied electric field
Such a birefringence is able to modulate the polarization of an incoming laser pulse impinging onto the crystal proportionally to the electric field amplitude

Summary

Introduction

Multi-Terawatt laser pulses with femtosecond duration have opened new horizons in research of nonlinear transient phenomena like astrophysics in laboratory[1,2], particle acceleration[3,4,5], material science[6,7], surface phenomena[8] (breakdown and surface manipulation), nuclear[9] and medical physics[10,11]. The first one consists in ultra-short EM pulses in the THz domain[21,22] and is mostly related to the current associated with fast electrons Their propagation, measured through coil-like structures[23] or wires[24,25], occurs on tens-picosecond time scale. For the first time, single-shot snapshots with femtosecond resolution of the ultra-short EM pulses and fast electrons emitted during the interaction between a multi-terawatt laser and a sharp metallic target. The results, corroborated by Particle-In-Cell (PIC) simulations, provide a more complete picture of interaction processes at the sub-picosecond timescale and highlight the ultra-fast dynamics involved during and soon after the transfer of energy from the laser pulse to the target

Methods

Results

Conclusion