Compression of TW class laser pulses in a planar hollow waveguide for applications in strong-field physics

Amélie Jarnac,Filippo Campi,Cord L Arnold,Piotr Rudawski,Fernando Brizuela,André Mysyrowicz,Per Johnsson,Linnea Rading,Christoph M Heyl,Aurélien Houard,Byunghoon Kim,Anne L’Huillier

doi:10.1140/epjd/e2014-50558-7

Abstract

We demonstrate pulse post-compression of a TW class chirped pulse amplification laser employing a gas-filled planar hollow waveguide. A waveguide throughput of 80% is achieved for 50 mJ input pulse energy. Good focusability is found and after compression with chirped mirrors a pulse duration of sub-15 fs is measured in the beam center. Whereas a total energy efficiency of ≈70% should be achievable, our post-compressor currently delivers 20 mJ output pulse energy (≈40% efficiency), mostly limited by apertures of chirped mirrors and vacuum windows. The viability of the planar hollow waveguide compression scheme for applications in strong-field physics is demonstrated by generating high-order harmonics in a pulsed Ar gas cell.

Highlights

Few-cycle laser pulses, i.e. pulses so short that the pulse envelope encloses only a few cycles of the field, have become indispensable tools in optics and related sciences, such as High-order Harmonic Generation (HHG) [1], attosecond science [2], strong-field physics [3], and acceleration of particles [4]
While low-energy, few-cycle pulses can today routinely be obtained from Titanium:Sapphire (Ti:Saph) based ultrafast oscillators [5], the output of chirped pulse amplification (CPA) femtosecond lasers hardly reaches below 20 fs pulse duration, mostly due to gain-bandwidth-narrowing
We demonstrate the suitability of such pulses for applications in high-field physics by performing HHG in a pulsed Ar gas cell

Summary

Introduction

Few-cycle laser pulses, i.e. pulses so short that the pulse envelope encloses only a few cycles of the field, have become indispensable tools in optics and related sciences, such as High-order Harmonic Generation (HHG) [1], attosecond science [2], strong-field physics [3], and acceleration of particles [4]. By use of gas-filled planar hollow waveguides for post-compression, the pulse energy can be up-scaled by increasing the beam size in one spatial direction, while keeping the intensity inside the waveguide at levels benefiting efficient self-phase modulation, but limiting ionization. A theoretical model describing a stability regime for energy up-scaling of the planar hollow waveguide compression scheme was introduced [23] The results from these early experiments were summarized in an article [24], which discusses in detail how the detrimental transverse dynamics inside the waveguide can be balanced in order to support energies exceeding the current limitations in pulse post-compression with hollow capillaries and filamentation. The harmonic cut-off is significantly increased compared to that obtained with longer driving pulses

Experiments and discussion

Pulse duration measurement

Findings

High-order harmonic generation

Conclusion and outlook