Spectral interferometry with waveform-dependent relativistic high-order harmonics from plasma surfaces

Dmitrii Kormin,Antonin Borot,Márk Aladi,William Dallari,Boris Bergues,Guangjin Ma,István B Földes,Laszlo Veisz

doi:10.1038/s41467-018-07421-5

Abstract

The interaction of ultra-intense laser pulses with matter opened the way to generate the shortest light pulses available nowadays in the attosecond regime. Ionized solid surfaces, also called plasma mirrors, are promising tools to enhance the potential of attosecond sources in terms of photon energy, photon number and duration especially at relativistic laser intensities. Although the production of isolated attosecond pulses and the understanding of the underlying interactions represent a fundamental step towards the realization of such sources, these are challenging and have not yet been demonstrated. Here, we present laser-waveform-dependent high-order harmonic radiation in the extreme ultraviolet spectral range supporting well-isolated attosecond pulses, and utilize spectral interferometry to understand its relativistic generation mechanism. This unique interpretation of the measured spectra provides access to unrevealed temporal and spatial properties such as spectral phase difference between attosecond pulses and field-driven plasma surface motion during the process.

Highlights

The interaction of ultra-intense laser pulses with matter opened the way to generate the shortest light pulses available nowadays in the attosecond regime
Coherent wake emission (CWE) provides temporally coherent and synchronized XUV harmonics resulting in attosecond temporal bunching[21,22] but with a chirp related to sub-laser-cycle dynamics of plasma electrons[23], which makes it less attractive for applications
carrier-envelope phase (CEP) dependence and control of CWE harmonics was already demonstrated[51] and isolation was reached with tilting the pulse front of the intense few-cycle driver laser and producing a manifold of isolated attosecond pulses (APs) propagating in different directions[52]

Summary

Introduction

The interaction of ultra-intense laser pulses with matter opened the way to generate the shortest light pulses available nowadays in the attosecond regime. We present laserwaveform-dependent high-order harmonic radiation in the extreme ultraviolet spectral range supporting well-isolated attosecond pulses, and utilize spectral interferometry to understand its relativistic generation mechanism. This unique interpretation of the measured spectra provides access to unrevealed temporal and spatial properties such as spectral phase difference between attosecond pulses and field-driven plasma surface motion during the process. CEP dependence and control of CWE harmonics was already demonstrated[51] and isolation was reached with tilting the pulse front of the intense few-cycle driver laser and producing a manifold of isolated APs propagating in different directions[52]. The simultaneous measurement of the laser waveform provides clear demonstration of the CEP dependence of the underlying relativistic laser–plasma interaction

Methods

Results

Conclusion