The invention of the laser gave birth to the era of nonlinear optics, which today plays an important role in many scientific, industrial and medical applications. All these applications benefit from the availability of compact lasers in the visible area of ​​the electromagnetic spectrum. The situation is different at XUV wavelengths, where very large facilities (called free electronic lasers) are built to generate intense XUV pulses. The Hamburg flash, which stretches for hundreds of meters, is an example. Intensive small XUV sources based on HHG have also been developed. However, these sources still have tens of thousands of meters of footprints, and have so far been proven only in a few universities and research institutes around the world.

A team of researchers from the Max Bourne Institute (Berlin, Germany), ELI-ALPS (Szeged, Hungary), and INCDTIM (Cluj-Napoca, Romania) recently developed a new project to create intensive XUV legumes. Their concept is based on HHG, which is based on the concentration of the infrared (NIR) laser pulse in a gas target. As a result, the NUR activating laser emits very small amounts of light through the harmonic frequencies, which are usually in the XUV region. To achieve intense XUV pulses, it is important to create as much XUV light as possible. This is usually done by creating a very large focus of the NIR pilot laser, which requires a large laboratory.

Scientists at the Max Born Institute have shown that an intense XUV laser can be reduced to a configuration of only two meters. To do this, they used the following technique: Instead of generating XUV light on the NIR laser focus, they placed a very dense jet of atoms relatively far from the NIR laser focus, as shown in Figure 1. It has two main advantages: (1) The large jet position NRR beam generates many XUV photons. (2) The generated XUV beam is large and has a large deflection, so it can focus on a small point size. Large quantities of XUV photons combined with the small size of the XUV point make it possible to generate intense XUV laser pulses. Computer simulations by a team of researchers from ELI-ALPS and INCDTIM confirmed these results.

To prove that the generated XUV pulses are very intense, scientists have studied the multiphon ionization of argon atoms. They were able to increase the ionization of these atoms, which led to the ionic charge conditions of Ar2 + and Ar3 +. It requires the absorption of at least two and four XUV photons, respectively. Despite the small size of this intense XUV source, the XUV intensity achieved at 2 x 1014 W / cm2 is higher than many current XUV sources.

The new concept can be implemented in many laboratories around the world, and various research areas can benefit from it. This includes the autosecond spectroscopy of the pump, which is by far the most difficult to do. The new high-intensity, compact XUV laser exceeds the existing stability limit in this technology and can also be used to monitor the dynamics of electrons on very short time scales. Another area to benefit from is the imaging of nanoscale objects such as biomolecules. This would increase the likelihood that nanocosms would be used to make films on phertosecond or autosecond time scales.

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