M. Kozák,
P. Beck,
H. Deng,
J. McNeur,
N. Schönenberger,
C. Gaida,
F. Stutzki,
M. Gebhardt,
J. Limpert,
A. Ruehl,
I. Hartl,
O. Solgaard,
J. S. Harris,
R. L. Byer,
and P. Hommelhoff
Acceleration of sub-relativistic electrons with an evanescent optical wave at a planar interface
Opt. Express, 25 :19195 (August 2017)
Acceleration of sub-relativistic electrons with an evanescent optical wave at a planar interface
Opt. Express, 25 :19195 (August 2017)
Abstract:
We report on a theoretical and experimental study of the energy transfer between an optical evanescent wave, propagating in vacuum along the planar boundary of a dielectric material, and a beam of sub-relativistic electrons. The evanescent wave is excited via total internal reflection in the dielectric by an infrared (λ = 2 μm) femtosecond laser pulse. By matching the electron propagation velocity to the phase velocity of the evanescent wave, energy modulation of the electron beam is achieved. A maximum energy gain of 800 eV is observed, corresponding to the absorption of more than 1000 photons by one electron. The maximum observed acceleration gradient is 19 ± 2 MeV/m. The striking advantage of this scheme is that a structuring of the acceleration element’s surface is not required, enabling the use of materials with high laser damage thresholds that are difficult to nano-structure, such as SiC, Al2O3 or CaF2.