TELBE: High-Field High-Repetition-Rate Terahertz facility @ ELBE
The TELBE facility consists of unique highly intense accelerator-based sources of terahertz radiation in conjunction with a wide range of endstations for probing ultrafast terahertz-induced dynamics in various states of matter with highest precision. The TELBE sources offer CEP-stable, tunable, narrowband THz radiation with pulse energies of several microjoules at high repetition rates (see figure below). A synchronized coherent diffraction radiator provides broadband single-cycle pulses.
Typical TELBE undulator terahertz pulse energies as a function of terahertz frequency (left, 50 kHz repetition rate), and representative electric field transients for the undulator source (top right, after 0.3 THz bandpass filter) and the coherent diffraction radiator (CDR) (lower right).
Foto: Jan-Christoph Deinert
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].
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 November 2021):
| Radiator type | Electron charge / pC | Repetition rate / kHz | Pulse energy / μJ | Bandwidth / % | Frequency range / THz |
| Undulator | up to 250 |
10 to 500 |
<= 10 | 20 | 0.1 - 2.5 |
| Diffraction Radiator | up to 250 |
10 to 500 |
<=0.25 | 100 | 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 USP
- 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)
