High-Field High-Repetition-Rate Terahertz facility @ ELBE (TELBE)

 

TELBE Pulsenergien und typische Feldtransienten (2020) ©Copyright: Dr. Deinert, Jan-Christoph

Available TELBE terahertz pulse energies as a function of terahertz frequency (left), and representative electric field transients for the undulator source (after 0.3 THz bandpass filter) and the coherent diffraction radiator (CDR) (right).

Foto: Jan-Christoph Deinert

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As part of an upgrade of the ELBE accelerator one electron beamline has been modified to allow for the generation and acceleration of ultra short (< 150 fs) highly charged (up to 1 nC) electron bunches. This upgrade enables the operation of High-Field THz sources based on superradiant THz emission at the ELBE accelerator and thereby opens up the opportunity to generate carrier-envelope phase stable high-field THz pulses with extremely flexible paramaters with respect to repetition rate, pulse form and polarization. Since 2014 the fs electron beamline and the pilot-TELBE facility have been taken into operation [1,2] and have been comissioned aiming to achieve the following design parameters:

Radiator type  Electron charge / pC Repetition rate / kHz  Pulse energy / μJ  Bandwidth / % number of Field cyles   Timing / fs Frequency range / THz
  Undulator < 100  =< 1.3 x 104 1  ~20 8 < 30 (FWHM) 0.1 - 3 (tunable by user)
< 1000  =< 500 100  ~20 8 < 30 (FWHM) 0.1 - 3 (tunable by user)

Diffraction radiator

 < 100  =< 1.3 x 104 0.25 100 1 < 30 (FWHM) 0.1 - 3
< 1000 =< 500 25 100 1 < 30 (FWHM) 0.1 - 3

TELBE is open since 2016 as user facility, proposals can be submitted via the central user portal. The available in-lab laser infrastructure allows THz-pump laser-probe experiments within a wide range of experimental schemes and probe beam properties. Please note that the TELBE sources are under constant development, current achievable parameters are (as of February 2021):

Radiator type   Electron charge / pC Repetition rate / kHz  Pulse energy / μJ Bandwidth / %   Number of field cycles  Timing / fs  Frequency range / THz
Undulator  up to 250
  25 to 500
  <= 10  20  8  < 30  0.1 - 1.5
Diffraction Radiator  up to 250
  25 to 500
  <=0.25  100  1  < 30  0.1 - 1.1

For further details and discussions of potential projects and experimental ideas please contact the TELBE team leaders (see below). The strong in-house expertise on ultrafast spectroscopic methods and the broad scientific background of the TELBE team allows strong on-site support during experimental planning, set-up and execution.

Pulses from both radiator types are transported into a dedicated, climatized laser laboratory which is equipped with the following infrastructure:

  • fs laser-amplifier system 1: Coherent, Inc. RegA 9000
  • fs laser-amplifier system 2: Coherent, Inc. RegA 9040
  • fs laser-amplifier system 3: Coherent, Inc. Legend Elite
  • fs laser amplifier system 4: Coherent Inc. Astrella HE
  • FTIR spectrometer: BRUKER 80V
  • 10 T split-coil magnet with optical access: OXFORD INSTRUMENTS SPECIAL SM4000-10
  • Optical cryostats (liquid He cooling, vacuum and contact gas environment, 3.4 K to 500 K)
  • High-Field THz pump probe set-ups based on optical rectification, photoconductive emitters,...
  • ONLINE Pulse-to-pulse THz diagnostic endstation (fs arrivaltime, THz - spectrum & pulse energy,...)
  • TR - Faraday rotation endstation
  • TR - THz emission endstation [4]
  • TR - Scattering-type nearfield microscopy [5]
  • Extensive THz manipulation and diagnostics equipment

A  novel prototype data aquisition scheme [2] has been developed that allows to determine the arrivaltime jitter and intensity instability of each individual TELBE THz pulse, enabling online and post mortem correction of the acquired data.

Contact:

Dr. Sergey Kovalev (TELBE team leader, beamline scientist) 

Dr. Jan-Christoph Deinert (TELBE deputy team leader, Young Investigator Group "THz-driven dynamics at surfaces")

[1] B. Green et. al., "High-field High-repetition-rate Sources for the Coherent THz Control of Matter", Scientific Reports 6 22256 (2016). (nature.com)

[2] S. Kovalev et al., "Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates", Struct. Dyn. 4 024301 (2017). (scitation.org)

[3] S Kovalev et al., "Selective THz control of magnetic order: new opportunities from superradiant undulator sources", J. Phys. D: Appl. Phys. 51, 114007 (2018). (HZDR repository)

[4] Hafez, H.A., Kovalev, S., Deinert, JC. et al., "Extremely efficient terahertz high-harmonic generation in graphene by hot Dirac fermions" Nature 561, 507–511 (2018). (nature.com)

[5] F. Kuschewski et. al., "Optical nanoscopy of transient states of matter", Scientific Reports 5, 12582 (2015). (nature.com)