Operated by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), the free-electron-laser facility FELBE provides picosecond infrared pulses. Two free-electron lasers cover the mid- and far-infrared spectral range from 4 - 250 µm. The electron bunches for the FELBE are provided by the superconducting radio-frequency linear accelerator ELBE. FELBE can operate in three different modes:
Continuous pulsing with a repetition rate of 13 MHz, pulsing with 1 kHz by applying a pulse picker, and macrobunch operation with bunch length > 100 µs and macrobunch repetition rates ≤ 25 Hz. Pulse duration and pulse energy vary with wavelength and lie in the range from 1 - 25 ps and 100 nJ - few µJ, respectively.

The user labs at FELBE are equipped mainly for time-resolved spectroscopy. Various tabletop near-infrared and THz sources can be synchronised to FELBE and setups exist for single-colour and two-colour pump-probe experiments, time-resolved photoluminescence measurements, near-field spectroscopy, and Fourier-transform infrared spectroscopy. Samples can be studied in an 8 T split-coil magnet with optical access. Furthermore FELBE is linked to the Dresden High Magnetic Field Laboratory, which enables infrared spectroscopy in pulsed magnetic fields up to 70 T (150 ms magnetic pulse duration).

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Beam parameters


Photon energy [meV]

5 - 300

Wavelength [µm]

4 - 250


Linear; circular possible for some wavelengths

Estimated pulse length [ps]

1 - 25

Repetition rate [MHz]

13, 1 KHz; also macrobunch (< 25 Hz)
rate <25 Hz

Pulse Energy [µJ]

0.1 - 2

Peak power [MW]

up to 1

Average power [W]

up to 20

FEL mode


FEL bandwidth [%] (FWHM)

0.3 – 1.5