Coherent Sensing

Welcome to our group website!

Our work is dedicated to laser spectroscopy and coherent sensing.  We use ultrashort laser pulses on the femtosecond time scale to learn more about the optical properties of atoms and molecules, so far mostly in the gas phase. Recently, we have extended our research focus to applications of photochemical and biophysical relevance.

Coherent Sensing Group in October 2023
From left to right: Florian Lindorfer, Robert Di Vora, Armin Speletz, Mithun Pal, Birgitta Schultze-Bernhardt, Emily Hruska, Lukas Fürst, Alexander Eber, Elias Ehl, Adrian Kirchner. Not on the picture: Kevin Nusshold.


1. Dual comb spectroscopy in different spectral regions

Dual Comb Spectroscopy combines high spectral resolution with broad spectral coverage and short measurement times. In the recent years, this spectroscopic method has proven its capabilities in molecular spectroscopy in different spectral regions ranging from the visible across the infrared spectral region into the THz domain, see for example [1-3]. We are currently expanding dual comb spectroscopy for different applications ranging from the detection of unknown gas mixtures to Raman spectroscopy for the examination of biophysical samples [2].

2. Electronic Fingerprint Spectroscopy

So far our knowledge about (extreme) UV characteristics of atomic and molecular gasses and condensed matter is scars due to the lack of readily available laser sources in this spectral region. Especially high resolution spectroscopic studies with an advanced relative spectral resolution on the order of 10-5 and 10-6 still have to be performed at synchrotron sources that are only restrictedly accessible. In the recent years, the high power laser technology has prospered such that table top high photon flux (X)UV sources with high repetition rates become possible not only with enhancement cavities [4] but also in single pass geometry. However, laboratory XUV spectroscopic studies are still limited by conventional grating spectrometers that typically provide a spectral resolution on the order of 10-3 [5,6].  At the IEP, we are currently developing the world`s first UV dual comb spectrometer that will enable an unparalleled relative spectral resolution of up to 10-9 outperforming synchrotron-based spectrometers by up to three orders of magnitude (see figure 1) and grating based XUV spectrometers by even up to six orders of magnitude [7].

This research is funded the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 947288) and by the Austrian Science Fund FWF START program (grant agreement no. Y1254N).

Figure 1

Figure 1: Extreme Ultraviolet (XUV) Dual Comb Spectroscopy yielding ultra-broadband (>150 THz) absorption spectra of atoms and molecules with an unparalleled spectral resolution on the order of µeV. This resolution is hitherto unprecedented for XUV table top sources but mandatory for example for the resolution of high principal quantum numbers in Rydberg series (the example shows the Rydberg series in argon converging against the ionization limit at 15.76 eV).

Bachelor, Master and PhD theses
For potential projects in the field of laser spectroscopy, please contact

Recent news

September 2023

Elias EHL joins our team


Herzlich Wilkommen, Elias!

September 2023

Emily HRUSKA joins our team


Herzlich Wilkommen, Emily!

July 2023

Mithun PAL joins our team


Herzlich Wilkommen, Mithun!

June 2023

Coherent Sensing Group in June 2023

From left to right: Robert Di Vora, Adrian Kirchner, Birgitta Schultze-Bernhardt, Lukas Fürst, Armin Speletz, Alexander Eber. Not on the picture: Kevin Nusshold.

May 2023

Armin SPELETZ joins our team


Herzlich Wilkommen, Armin!

April 2023

Group Excursion to the Austrian Academy of Sciences (ÖAW) in Vienna: The German Physical Society (DPG) and the Austrian Physical Society (ÖPG) organized this year`s Lise Meitner Lecture with the ÖAW. Donna Strickland shared her insights and experiences with quite different aspects of chirped pulse amplification in her talk on “Generating High-Intensity, Ultrashort Optical Pulses”.

Event link:

From left to right: Lukas Fürst, Alexander Eber, Birgitta Bernhardt, Adrian Kircher, Robert Di Vora, together with Archduke Rainer Ferdinand from Austria.
Donna Strickland talking about her first struggles with high harmonic generation.

October 2022

With the start of my university professorship, we are expanding our research focus as Coherent Sensing group to applied environmental sciences including atmospheric monitoring, trace gas sensing and the investigation of novel materials for photo-voltaics.

Stay tuned for the latest developments, open positions or contact me directly:

October 2022

Robert DI VORA joins our team


Herzlich Wilkommen, Robert!

Juni 2022

Adrian KIRCHNER joins our team


Herzlich Wilkommen, Adrian!

April 2022

"Wie man mit Lasern fotografiert"

Read about our latest research projects in our contribution to the
ÖAW Junge Akademie Blog @ DER STANDARD

February 2022

First NUV Dual Comb Spectroscopy

Lukas Fürst optimizing his first interferogram, produced by two interfering near-ultraviolet frequency combs.

October 2021

First field campaign of dual comb spectroscopy in Europe

Inital measurements of our urban atmosphere above the TUG Campus Neue Technik, together with the Lienhart Group, Geodesy, TU Graz

September 2021

Lukas FÜRST joins the team


Herzlich Wilkommen Lukas!

July 2021

Dual Comb Spectroscopy Lab II starts operating

Our spectroscopic investigations can be expanded thanks to our new second laboratory!

May 2021

ERC Starting Grant ELFIS launches

ELFIS rocks! Stay tuned for our next-level spectroscopy platform in the EXTREME Ultraviolet brought to you by the European Research Council!

March 2021

Alexander EBER joins the team


Herzlich Wilkommen Alex!

Dezember 2020

FWF START Project ELFIS starts

Electronic Fingerprint Spectroscopy unravels photo-induced dynamics in the near ultraviolet spectral region.

© Lunghammer

3rd September 2020


Birgitta Bernhardt receives the renowned prize for her project to investigate the interaction between UV light and matter in spectral ranges that have not yet been extensively researched.

TUG Pressemitteilung


© FWF/Sabine Hoffmann

17th June 2020


With her project Electronic Fingerprint Spectroscopy, Birgitta Bernhardt will develop a novel spectrometer that enables a closer look onto electron dynamics in molecules.

TUG Pressemitteilung


June 2020:

Online Video

Have a quick look what we are up to:

Iodine Cell

March 2020

VIS Spectrometer ready

Our VIS Dual Comb Spectrometer starts its operation.
Central wavelength: 515nm

July 2019

Our article
"Ultrafast quantum control of ionization dynamics in krypton"
was one of the most read* Nature Communications physics articles in 2018!

*Check out the full collection of Nature Communications:
Top 50: Physics

Lab Fotos

Dual Comb Lab
Dual Comb Lab
Dual Comb Spectrometer operating in the visible spectral region
Iodine Cell
NIR-VIS Dual Comb Spectrometer

Selected Publications

[1] B. Bernhardt, A. Ozawa, P. Jacquet, M. Jacquey, Y., T. Udem, R. Holzwarth, G. Guelachvili, T. W. Hänsch and N. Picqué, Cavity-enhanced dual-comb spectroscopy, Nature Photonics 4, 55-57 (2009)

[2] T. Ideguchi, S. Holzner, B. Bernhardt, G. Guelachvili, N. Picqué and T. W. Hänsch, Coherent Raman spectro-imaging with laser frequency combs, Nature 502, 355 (2013)

[3] T. Ideguchi, B. Bernhardt, G. Guelachvili, T.W. Hänsch and N. Picqué, Raman-induced Kerr-effect dual-comb spectroscopy, Optics Letters, Vol. 37, 4498 (2012)

[4] B. Bernhardt, A. Ozawa, A. Vernaleken, I. Pupeza, J. Kaster, Y. Kobayashi, R. Holzwarth E. Fill, F. Krausz, T. W. Hänsch, and Th. Udem, Vacuum ultraviolet frequency combs generated by a femtosecond enhancement cavity in the visible, Optics Letters 4, 503 (2012)

[5] B. Bernhardt, A. R. Beck, X. Li, E. R. Warrick, M. J. Bell, D. J. Haxton, C. W. McCurdy, D. M. Neumark and S. R. Leone, High-spectral-resolution attosecond absorption spectroscopy of autoionization in xenon, Physical Review A 89, 023408 (2014)

[6] K. Hütten, M. Mittermair, S. Stock, R. Beerwerth, V. Shirvanyan, J. Riemensberger, A. Duensing, R. Heider, M. Wagner, A. Guggenmos, S. Fritzsche, N. M. Kabachnik, R. Kienberger and B. Bernhardt, Ultrafast Quantum Control of Ionization Dynamics, Nature Communications 9, 719 (2018)

[7] V. Schuster, C. Liu, R. Klas, P. Dominguez, J. Rothhardt, J. Limpert, and B. Bernhardt, Ultraviolet dual comb spectroscopy: a roadmap, Optics Express 29, Issue 14, 21859-21875 (2021)


All images © TU Graz/Institute of Experimental Physics

Institut of Experimental Physics
Graz University of Technology
Petersgasse 16
8010 Graz

Group Leader
Univ.-Prof. Dipl.-Phys. (Univ.) Dr.rer.nat.

Tel.: +43 (0) 316 / 873 - 8663
Fax: +43 (0) 316 / 873 - 8655

Group Members

Univ.-Prof. Dipl.-Phys. (Univ.) Dr.rer.nat. Birgitta BERNHARDT
Curriculum Vitae
+43 (316) 873-8663

BSc DI Alexander EBER
+43 (316) 873-8152


+43 (316) 873-8928


+43 (316) 873-8147

+43 (316) 873-8152


+43 (316) 873-8146




BSc MSc Ph D. Mithun PAL


+43 (316) 873-8662

BSc MSc Elias EHL
+43 (316) 873-8662