Lightwave controlled nanoscale electron acceleration sets the pace

Extremely short electron bunches are key to many new

applications including ultrafast electron microscopy and table-top free-electron

lasers. A German team of physicists from Rostock University, the Max Born

Institute in Berlin, the Ludwig-Maximilians-Universität Munich, and the Max

Planck Institute of Quantum Optics in Garching has now shown how electrons can

be accelerated in an extreme and well-controlled way with laser light, while crossing

a silver particle of just a few nanometers. Of particular importance for

potential applications is the ability to manipulate the acceleration process,

known as a swing-by maneuver from space travel, with the light waveform. This

could facilitate an all-optical generation of attosecond electron pulses.

When

metal clusters, small nanoparticles consisting of just a few thousand atoms,

are exposed to intense laser light, electrons inside the particle are excited

to a swinging collective motion. The electron cloud’s motion, a plasmon, can be

excited resonantly with light of a suitable color leading to very high

amplitudes and an enhanced electric field inside the cluster. In the

experiment, which was conducted at the Institute of Physics in Rostock, a team

of researches around Prof. Thomas Fennel has now deliberately exploited this

enhanced near-field. With so-called two-color laser pulses the scientists tailored

the plasmonic field via the waveform of the light field. This led to a

controlled slingshot-type acceleration of electrons traversing the nanoparticle

within only one optical cycle. These experimental results, together with their

interpretation by a theoretical model, were now published in the journal Nature

Communications.

In their study, the

researchers demonstrated that electronic processes in clusters can be

controlled with the waveform of laser light. The few nanometer-sized clusters

serve as ideal experimental and theoretical model systems for investigating new

physical effects in the light matter interaction of nanostructures. “In our

experiment we could show that electrons can gain energies of up to one

kiloelectron volt within just one optical cycle in the nanoaccelerator. This

corresponds to an enhancement of more than one order of magnitude with respect

to the strong-field ionization of atoms”, describes Dr. Josef Tiggesbäumker from

the Institute of Physics in Rostock, who has developed the setup for the

experiments together with first author Dr. Johannes Passig from the team around

cluster physicist Prof. Karl-Heinz Meiwes-Broer. „The acceleration of electrons

via near-field-assisted forward scattering can be switched with attosecond

precision (1 attosecond = 1 billionth of a billionth of a second) by tailoring

the light waveform“, adds Prof. Matthias Kling from the

Ludwig-Maximilians-Universität Munich and the Max Planck Institute of Quantum

Optics in Garching, who provided the technology for the generation of the

phase-controlled laser pulses. „The control with just and only the laser light paves

new ways for the intensely researched area of light-based particle

acceleration”, sums up Fennel from the University Rostock and the Max Born Institute

in Berlin, who developed the concept for the study. The researchers plan to

realize the acceleration principle in multiple stages in the future to

investigate its potential applications in laser-driven grating accelerators.

Original publication:
Johannes Passig, Sergey Zherebtsov, Robert Irsig, Mathias Arbeiter, Christian Peltz, Sebastian Göde,Slawomir Skruszewicz, Karl-Heinz Meiwes-Broer, Josef Tiggesbäumker, Matthias F. Kling, Thomas Fennel
Nanoplasmonic electron acceleration by attosecond-controlled forward rescattering in silver clusters
Nature Communications 8, 1181 (2017), DOI: 10.1038/s41467-017-01286-w
http://dx.doi.org/10.1038/s41467-017-01286-w

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