Prof. Dr. Sascha Schäfer
Institute of Physics, University of Oldenburg, Germany
 

Coherent electron-light interactions probed by ultrafast transmission electron microscopy

Ultrafast transmission electron microscopy (UTEM) is a promising technique which provides access to ultrafast dynamics on nanometer length scales [1,2]. In UTEM, a pulsed electron beam with 100-fs-scale bunch duration is utilized to stroboscopically probe optically triggered processes. Dynamics in structural, electronic and spin degrees of freedom are generally accessible in UTEM by utilizing the versatile imaging and diffraction capabilities of state-of-the-art electron microscopes.

In the present talk, I will give an overview on our current UTEM developments at the University of Oldenburg. Furthermore, I will detail the application of UTEM for the investigation of coherent electron-light interactions in optical near-fields [3-5], including the quantitative characterization of transient optical near-fields, the transverse and longitudinal optical control of free-electron pulses and the generation of  phase-locked cathodoluminescence in microresonator structures [6].

[1] A. H. Zewail, A. H. Four-dimensional electron microscopy. Science 328, 187–93 (2010).
[2] A. Feist, N. Bach, N. Rubiano da Silva, Th. Danz, M. Möller, K. E. Priebe, T. Domröse, J. G. Gatzmann, S. Rost, J. Schauss, S. Strauch, R. Bormann, M. Sivis, S. Schäfer, C. Ropers, Ultrafast transmission electron microscopy using a laser-driven field emitter: femtosecond resolution with a high coherence elec-tron beam, Ultramicroscopy 176, 63-73 (2017).
[3] A. Feist, K. E. Echternkamp, J. Schauss, S. V. Yalunin, S. Schäfer, C. Ropers. Quantum coherent optical phase modulation in an ultrafast transmission electron microscope. Nature 521, 200–203 (2015).
[4] K. E. Echternkamp, A. Feist, S. Schäfer, C. Ropers, Ramsey-type phase control of free electron beams, Nature Phys. 12, 1000-1004 (2016).
[5] K. E. Priebe, C. Rathje, S. V. Yalunin, Th. Hohage, A. Feist, S. Schäfer, C. Ropers, Attosecond electron pulse trains and quantum state reconstruction in ultrafast transmission electron microscopy, Nature Photonics 11, 793 (2017).
[6] N. Müller, V. Hock, Chr. Rathje, H. Koch, S. Schäfer, Broadband coupling of fast electrons to high-Q whispering gallery mode resonators, in preparation.