High-Field High-Repetition-Rate Terahertz facility @ ELBE (TELBE)
Artistic view on a THz driven spin excitation in NiO measured by transient Faraday rotation after resonant excitation of the antiferromagnetic mode by a 1 THz pulse from the TELBE undulator source [2,3]. The achieved dynamic range in this experiment was 10000.
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 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 |
Pulses from both radiator types are transported into a dedicated, climatized laser laboratory which is equipped with the following infrastructure:
- fs laser-amplifyier system 1: COHERENT RegA 9000
- fs laser-amplifyier system 2: COHERENT Legend Elite
- FTIR spectrometer: BRUKER 80V
- 10 T split-coil magnet with optical access: OXFORD INSTRUMENTS SPECIAL SM4000-10
- 2 x High-Field THz pump probe set-ups based on optical rectification
- ONLINE Pulse-to-pulse THz diagnostic endstation (fs arrivaltime, THz - spectrum & pulse energy,....)*
- TR - Faraday rotation endstation*
- TR - THz emission endstation*
- THz TELBE pump THz probe endstation*
- TR - Scattering-type nearfield microscopy [1]*
* under development by the THODIAC collaboration.
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 postmortem correction of the taken data.
NOTE! the currently achievable parameters are [3]:
| Radiator type | Electron charge / pC | Repetition rate / kHz | Pulse energy / μJ | Bandwidth / % | Number of field cycles | Timing / fs | Frequency range / THz |
| Undulator | 100 | 100 | <= 1 | 20 | 8 | < 30 | 0.1 - 1.1 |
| Diffraction Radiator | 100 | 100 | <=0.25 | 100 | 1 | < 30 | 0.1 - 1.1 |
Despite the fact that TELBE is still under development and can only provide preliminary parameters it is already open for first experimental proposals. To ensure most optimal performance TELBE beamtime is scheduled into 2 compact beamtime blocks per semester.
Contact:
Dr. Sergey Kovalev (Multi-color pump-probe, TELBE - Laser synchronization)
Dr. Michael Gensch (TELBE experiments, ARD test facility)
[1] F. Kuschewski et. al., "Optical Nanoscopy of transient states of Matter", Scientific Reports 5 (2015), 12582.
[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 (2017), 024301
[3] B. Green et. al., "High-field High-repetition-rate Sources for the Coherent THz Control of Matter", Scientific Reports 6 (2016), 22256.
