Demonstration of sub-luminal propagation of single-cycle terahertz pulses for particle acceleration

Walsh, D.A. and Lake, D.S. and Snedden, E.W. and Cliffe, M.J. and Graham, D.M. and Jamison, S.P. (2017) Demonstration of sub-luminal propagation of single-cycle terahertz pulses for particle acceleration. Nature Communications, 8 (1): 421. ISSN 2041-1723

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The sub-luminal phase velocity of electromagnetic waves in free space is generally unobtainable, being closely linked to forbidden faster than light group velocities. The requirement of sub-luminal phase-velocity in laser-driven particle acceleration schemes imposes a limit on the total acceleration achievable in free space, and necessitates the use of dispersive structures or waveguides for extending the field-particle interaction. We demonstrate a travelling source approach that overcomes the sub-luminal propagation limits. The approach exploits ultrafast optical sources with slow group velocity propagation, and a group-to-phase front conversion through nonlinear optical interaction. The concept is demonstrated with two terahertz generation processes, nonlinear optical rectification and current-surge rectification. We report measurements of longitudinally polarised single-cycle electric fields with phase and group velocity between 0.77c and 1.75c. The ability to scale to multi-megavolt-per-metre field strengths is demonstrated. Our approach paves the way towards the realisation of cheap and compact particle accelerators with femtosecond scale control of particles.

Item Type:
Journal Article
Journal or Publication Title:
Nature Communications
Uncontrolled Keywords:
?? general biochemistry,genetics and molecular biologygeneral chemistrygeneral physics and astronomybiochemistry, genetics and molecular biology(all)chemistry(all)physics and astronomy(all) ??
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Deposited On:
18 Jun 2018 07:46
Last Modified:
16 Jul 2024 10:45