Instrumentation

Probe light sources

The default probe laser is a 800 nm Coherent RegA 9040 cw-pumped titanium sapphire regenerative laser amplifier. This laser is seeded by a Coherent Vitara, which is synchronized to the ELBE master oscillator via a stabilized fiber link and the Coherent Synchrolock system. The RegA delivers pulses with about 6 µJ pulse energy at flexible repetition rates between 10 kHz and 250 kHz. In TELBE experiments it is typically run at twice the frequency of the TELBE source in order to enable subtraction of probe signals with and without THz drive. The minimum pulse duration of the RegA is < 40 fs.

The short pulses from the RegA can be converted to other wavelengths, including white-light continuum, using nonlinear crystals. We are also working on offering additional mid-infrared pumping at lower repetition rate (currently 1 kHz). Further, broadband THz probing using a photoconductive antenna source driven by the RegA is possible as well.

If you are interested in an experiment that would need additional infrared pumping or have special requirements regarding the probe light specifications, get in contact with us.

Sample environments

Sample environments include several cryostats with temperature range down to < 2 K and up to 310 K. We also operate an Oxford Instruments Spectromag SM4000 magnet cryostat which reaches magnetic flux densities up to 7 T.

Our cryostats place the sample either in vacuum, He exchange gas or a He jet. The latter two enable lowest temperatures and a particularly good heat transport away from the sample. Cryostat windows are made from Mylar as default material for good THz transmission. Depending on the experimental requirements we can change window materials in some of our cryostats.

The whole THz light path can be purged with dry nitrogen to prevent THz absorption by residual water in the laboratory atmosphere. 

Detection setups

Generally, our detection setups are tailored towards the requirements of each individual experiment. Standard optical components for NIR-VIS and THz spectral ranges are available.

In optical probe experiments we typically use pairs of photodiode detectors for balanced detection schemes. This covers detections methods like electro-optic sampling, Faraday and Kerr rotation as well as transient transmission and reflectivity. For detecting visible light emission we can use photomultipliers. Our detectors can also be connected to optical spectrometers in order to spectrally resolve the THz-driven dynamics in the sample.