Quantum Electronics

Recent Research Results

Spectral broadening and compression of laser pulses is of central importance for many applications. Here, the laser-matter interaction is confined to gas-filled novel anti-resonant hollow-core fibers (ARHF), which enable efficient guiding of intense light inside the fiber. Our experiments with Kr-filled ARHF have shown more than an octave spectral broadening [1]. Major advantages of ARHF are low loss, large-mode field diameter with effective single mode guidance from near IR to deep UV. This project tackles fundamental physical questions concerning the interaction of intense ultrashort mid-IR pulses with matter and provide a tunable ultrashort (down to a single optical cycle) source of near- to mid-IR radiation, which has applications in diverse areas of imaging. In another collaboration, we investigated experimentally interaction of sub-relativistic and relativistic femtosecond laser pulses with nanostructured solid dielectric targets. Interaction of ultra-intense laser radiation with  nanostructured targets is a hot topic in modern strong field physics [2], like the generation of high harmonics in solids up to ultra-hot and ultra-dense plasmas for applications in particle acceleration and hard X-ray generation. Experiments were carried out with different types wide-band gap, nanostructured semiconductors. Experiments at relativistic (about 1018 W/cm2) intensities were conducted at Jena’s JETi-40 multiTW laser system. Both the characteristic X-ray emission from transitions in high charge state ions generated in the targets [3] and the emitted particles were measured and simulated. Besides large-scale facilities such as synchrotrons and free electron lasers, only few approaches for brilliant XUV sources exist. The process of high harmonic generation (HHG) provides an elegant alternative for generating photons within the XUV and soft x-ray spectral region. Due to its outstanding properties the generated radiation is ideal for applications in spectroscopy, imaging and time-resolved studies. Beside further increasing the conversion efficiency, we will address the bandwidth of the harmonics, which is crucial for high resolution imaging. Our bright HHG sources emit narrow bandwidth harmonics with are essential for all high-resolution lens-less imaging techniques such as digital in-line-holography, coherent diffraction imaging and ptychography. In joint experiments with Prof. U. Kleineberg (MPI Munich), we demonstrated our capabilities to image close to highest possible resolution in a reasonable exposure time. In another cooperation with industry and the university hospital, we demonstrated a novel approach for rapidly classifying cell types: we measure the pattern of coherently diffracted extreme ultraviolet radiation and demonstrated that it is possible to distinguish different single breast cancer cell types. 

More recently, we started to explore other XUV sources such as laser-driven plasma sources and x-ray lasers for high resolution imaging [4]. They offer a higher flux and/or shorter wavelengths which is of great interest for approachig singleshot, table-top imaging in the water window. In parallel we work on realizing a proof of principle experiment for quantum ghost imaging [5] in the XUV. This ansatz holds promise for element specific sub-µm resolution imaging of biological samples without substantial radiation damage.

[1] Sollapur et al., Light: Sci. & Appl. 6, e17124 (2017).
[2] Hollinger et al., Nano Lett. 19, 3563 (2019).
[3] Samsonova et al., Phys. Rev. X 9, 021029 (2019).
[4] Tuitje et al., Light: Sci. & Appl. 9, 187 (2020).
[5] Sun et al., Opt. Express 27, 33652 (2019).

Link to the Quantum Electronics Group