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Contribution Invited Oral

SR and FEL sources and centers

Status of the FELBE THz/IR FEL Facility: Overview of the Machine Performance and User Activities


  • Dr. J. Michael KLOPF

Primary authors



The FELBE User Facility at the ELBE Center for High Power Radiation Sources offers two FELs dedicated to optical studies of materials over a wide range of the THz and IR spectrum (1.2 – 60 THz / 5 – 250 μm). Driven by a CW SRF linac, the FELBE FELs deliver beam at 13 MHz to a suite of eight User Labs. The high rep. rate CW operation provides high average power as well as outstanding data statistics, resulting in excellent S/N for even very challenging measurements. For example, the SNOM Group at the Technische Universität Dresden has pioneered methods using the tunable FEL beam with scattering scanning near-field infrared microscopy (s-SNIM) to achieve spectrally resolved nanoscale images with sub-wavelength resolution[1, 2]. While nanoscale imaging is gaining interest, the ultrashort pulses have long been the most important feature for most FELBE Users performing time-resolved measurements of transient processes in 2-dimensional materials[3], nanostructures[4], and correlated systems[5]. High field studies are also possible utilizing either an 8 T DC magnet or the 70 T pulsed field magnet at the adjacent Dresden High Field Magnet Lab[6, 7], and nonlinear processes can be driven by the μJ level pulse energy of both FELs.

Work is constantly underway to improve the machine, beam delivery, and the User Labs; and in 2017, a major upgrade was completed with the installation and commissioning of a new U37 undulator. This resulted in enhanced performance over the tuning range of the new FEL (7.5 – 60 THz / 5 – 40 μm), and User operation of the new U37 FEL began during the second half of 2017. A description of the performance and operational aspects of both FELs will be presented, with an emphasis on the commissioning measurements of the new U37 FEL. An overview of the FELBE User program, instrumentation, and infrastructure will be given along with highlights of several key User results.

  1. S. C. Kehr, Y. M. Liu, L. W. Martin, P. Yu, M. Gajek, S. Y. Yang, C. H. Yang, M. T. Wenzel, R. Jacob, H. G. von Ribbeck, M. Helm, X. Zhang, L. M. Eng and R. Ramesh, Nat. Commun. 2, 249 (2011).
  2. F. Kuschewski, H.-G. v. Ribbeck, J. Döring, S. Winnerl, L. M. Eng and S. C. Kehr, Appl. Phys. Lett. 108, 113102 (2016).
  3. M. Mittendorff, F. Wendler, E. Malic, A. Knorr, M. Orlita, M. Potemski, C. Berger, W. A. de Heer, H. Schneider, M. Helm and S. Winnerl, Nature Physics 11, 75-81 (2015).
  4. D. Stephan, J. Bhattacharyya, Y. H. Huo, O. G. Schmidt, A. Rastelli, M. Helm and H. Schneider, Appl. Phys. Lett. 108, 082107 (2016).
  5. A. Dienst, E. Casandruc, D. Fausti, L. Zhang, M. Eckstein, M. Hoffmann, V. Khanna, N. Dean, M. Gensch, S. Winnerl, W. Seidel, S. Pyon, T. Takayama, H. Takagi and A. Cavalleri, Nature Materials 12, 535 (2013).
  6. S. A. Zvyagin, M. Ozerov, E. Čižmár, D. Kamenskyi, S. Zherlitsyn, T. Herrmannsdörfer, J. Wosnitza, R. Wünsch and W. Seidel, Rev. Sci. Instrum. 80, 073102 (2009).
  7. M. Ozerov, J. Romhányi, M. Belesi, H. Berger, J. P. Ansermet, J. van den Brink, J. Wosnitza, S. A. Zvyagin and I. Rousochatzakis, Phys. Rev. Lett. 113, 157205 (2014).