Mainz 2017 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 49: Ultrashort Laser Pulses: Generation and Applications

Q 49.6: Talk

Thursday, March 9, 2017, 15:45–16:00, P 5

Synchronous interaction of free electrons with optical evanescent wave excited by femtosecond laser pulses — •Martin Kozak, Paul Beck, Joshua McNeur, Norbert Schönenberger, and Peter Hommelhoff — Department Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen

In recent years, the coherent interaction between optical near-fields and free-electrons became the basis for several experimental techniques focused on electron acceleration (dielectric laser accelerators, DLAs [1]) or energy-resolved electron imaging (photon-induced near-field electron microscopy, PINEM [2]). In classical DLA schemes, the synchronous near-field mode is excited by femtosecond laser pulse on top of a periodic dielectric element with period smaller than the laser wavelength [1]. Preparation of such a nanoscale phase-mask elements requires advanced nanofabrication. In this contribution we show the first demonstration of the synchronous interaction between free propagating electrons and an evanescent optical wave excited by total internal reflection on the flat surface of high-refractive index dielectrics. The maximum observed energy modulation is comparable to the grating-based DLA and is limited by the electron group velocity dephasing with respect to the phase velocity of the evanescent wave. Light coupling to the synchronous evanescent wave can be in future improved using the evanescent field of a transverse magnetic mode guided in an optical waveguide. [1] J. Breuer, and P. Hommelhoff, Phys. Rev. Lett. 111, 134803 (2013). [2] B. Barwick, D. J. Flannigan, and A. H. Zewail, Nature 462, 902-906 (2009).