Dr. Jan Rothhardt.

X-ray Spectroscopy and Microscopy

Dr. habil. Jan ROTHHARDT
Dr. Jan Rothhardt.
Image: Jan-Peter Kasper (University of Jena)
Dr. Jan Rothhardt
Image: Private

Dr. habil. Jan ROTHHARDT

Email: jan.rothhardt@uni-jena.de
Phone: +49 3641-9-47818

Dr. Rothhardt is head of the Soft X-ray Spectroscopy and Microscopy Group at the Helmholtz-Institute Jena and a member of the extended board of directors of the Helmholtz Institute Jena.

The Soft X-ray Spectroscopy and Microscopy group led by Jan Rothhardt is based at the Helmholtz Institute Jena and the Institute of Applied Physics. It focuses on the development and applications of high photon flux XUV and soft x-ray sources. Such sources are enabled by high harmonic generation with high average power femtosecond fiber lasers. This combination enables average powers up to the Milliwatt level in the XUV. In addition, these source provide excellent beam quality and spatial coherence, which enables coherent diffraction imaging down to the nanoscale. Moreover their ultrashort pulse duration enables ultrafast spectroscopy of fundamental dynamics in atoms, molecules and (highly-charged) ions.

Research Areas

Dr. Rothhardt investigates matter on smallest spatial and temporal scales by using modern laser-based XUV and soft x-ray sources. His research interests include:

  • Laser-based short wavelength sources
  • Nanometer scale imaging techniques
  • Ultrafast XUV spectroscopy of molecules and highly-charged ions

Teaching Fields

Dr. Rothhardt's teaching activities cover Nonlinear Optics, Laser Physics and Ultrafast Laser Spectroscopy.

Research Methods

Dr. Rothhardt’s group utilizes a variety of modern imaging and spectroscopy techniques including:

  • Coherent diffraction imaging and holographic techniques
  • XUV Laser spectroscopy & XUV Fourier-Transform spectroscopy
  • Ultrafast pump-probe spectroscopy

The group utilizes modern experimental equipment including:

  • High average power femtosecond lasers
  • High photon flux table-top XUV and soft x-ray sources
  • XUV and soft x-ray spectrometers and detectors
  • High performance computers and clusters for image processing

Recent Research Results

a) Simulation of the transmitted XUV light field behind a test sample. b) XUV image of the letter P obtained via Fourier-Transform-Holography (FTH). c) Helium-ion microscope image of the sample structure.
Picture: Rothhardt research group

Recent research of Dr. Rothhardt has been focused on the development and applications of high photon flux XUV and soft x-ray sources. This included the demonstration of phase matching and efficient high harmonic generation at high repetition rates in the tight focusing regime [1], resonant enhancement of the macroscopic yield of high harmonic generation by Fano-resonances [2], the demonstration of a high photon flux XUV sources delivering up to 1 mW of average power per harmonic in the XUV [3, 4]. These unique sources have recently been employed for lensless imaging at the nanoscale.

[1] Rothhardt et al., New J. Phys., 16, 033022 (2014).
[2] Rothhardt et al., Phys. Rev. Lett. 112, 233002 (2014).
[3] Hädrich et al., Nat. Photonics 8, 779 (2014).
[4] Klas et al., Optica 3, 1167 (2016).
[5] Tadesse et Al., Opt. Lett. 41, 5170 (2016).
[6] Tadesse et al., Sci. Rep. 8, 8677 (2018).
[7] Tadesse et al., Sci. Rep. 9, 1 (2019).
[8] Rothhardt et al., J. Opt. 20, 113001 (2018).

Link to the x-ray spectroscopy and microscopy group