JETi200 – Jenaer Titanium:Sapphire 200 Terawatt Laser System
The JETi200 is a commercial laser system based on Ti:sapphire with a peak power in excess of 200 TW. The laser pulses have an on-target energy of 4 J and a pulse duration of 17 fs. Using adequate off-axis parabolic mirrors these pulses can be focused to intensities of greater than 1021 W/cm2.
The short pulse duration is optimally suited to accelerate electron bunches to relativistic energies or to generate High Harmonics from solid surfaces in the x-ray range. Novel acceleration schemes for proton and ions from ultra-thin foils or droplet targets can be investigated as well. To make these experiments feasible, the temporal intensity contrast of the laser pulses has to be high enough to avoid any pre-plasma generation before the arrival of the peak of the pulse at the target. To this end, the JETi200 utilizes a double CPA amplification scheme. First, the stretched laser pulses are amplified to 1 mJ and compressed to a pulse duration of less than 30 fs. Then, non-linear temporal filtering via generation of cross-wave polarization (XPW) is used to enhance the temporal intensity contrast and broaden the spectrum of the laser pulses. These pulses are once again temporally stretched and further amplified in the second CPA stage. By shaping the amplitude of the laser's spectrum, gain narrowing is counteracted during amplification to the Joule-level and a spectral width of more than 100 nm is maintained. Finally, the laser pulses with an energy of 5.6 J are compressed to 17 fs. To increase the temporal contrast even further, a plasma mirror can be used resulting in an ASE level of below 10-13 and a pre-pulse level below 10-10. An adaptive mirror can be used to compensate accumulated wavefront aberrations from the laser chain and beamline allowing the user to focus the laser pulses to their diffraction limit or to shape the focal spots depending on the experimental needs.
Experiments using the JETi200 can be realized in two radiation protected target areas: one dedicated to experiments at the highest intensities and one designed for using long focal lengths. The latter is equipped with a few-cycle probe beam line that generates probe pulses with a temporal duration of less than 4 fs synchronized to the high power pump pulse with a duration of 17 fs.