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Institut für Experimentalphysik

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.

Nobelpreisträger Prof. Ferenc Krausz , Noble Lecture an der TU Graz — Coherent Sensing Group with 10 group members (missing: Florian Lindorfer) in December 2024.
Additionally on the photo: Marcus Ossiander, Raphael Dorner, Martin Schultze and one Nobel laureate.
From left to right: Mithun Pal, Elias Ehl, Robert Di Vora, Armin Speletz, Christoph Gruber, Marcus Ossiander, Emily Hruska, Raphael Dorner, Alexander Eber, Birgitta Schultze-Bernhardt, Ferenc Krausz, Lukas Fürst, Martin Schultze, Adrian Kirchner

Research

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].

Recently, we have developed a mobile dual comb spectrometer operating in the visible spectral region that we used for field monitoring of NO₂ in the city of Graz [8]. The world’s first broadband NUV dual comb spectrometer enabled the simultaneous detection of rovibrational states in formaldehyde and real time monitoring of this environmentally highly relevant pollution gas [9].

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
bernhardtnoSpam@tugraz.at

Visit our lab virtually via YouTube (in German):

Recent news

March 3^rd2025

International Women´s Day

Together with Young Academy Co-Member Jillian Petersen, I got the opportunity to present my research at the Austrian Academy of Sciences in Vienna. "Searching for Trace Gases and Species in the Sea and Atmosphere" was the title of the event on the eve of International Women's Day at the OeAW. It was great to discuss how our complex environment is connected and how we try to learn about it across different scientific disciplines.

Keine Exzellenz ohne Frauen

An interview (in German) related to this occasion can be found here: Ohne Vorbilder in die Forschung

© TU Graz

© TU Graz / Vice President of the Austrian Academy of Sciences Ulrike Diebold |ÖAW/Ludwig Schedl

© TU Graz / Class President of the Austrian Academy of Sciences Christiane Wendehorst |ÖAW/Ludwig Schedl

© TU Graz / Biologist Jillian Petersen |ÖAW/Ludwig Schedl

© TU Graz / Birgitta Schultze-Bernhardt |ÖAW/Ludwig Schedl

February 24^th2025

Publication Alert

Adrian’s work on “Ultra-broadband UV/VIS spectroscopy enabled by resonant dispersive wave emission of a frequency comb” got published in Optics Express!

Congratulations, Adrian!

Ultra-broadband UV/VIS spectroscopy enabled by resonant dispersive wave emission of a frequency comb

February 13^th2025

RIGOROSUM

Lukas Fürst
Ultraviolet Dual Comb Spectroscopy

Lukas Fürst successfully defended his doctoral thesis „Ultraviolet Dual Comb Spectroscopy“ on February 13^th 2025. We could invite Prof. Sandrine Galtier, Université Claude Bernard Lyon, to Graz as second reviewer.

Congratulations, Lukas!

February 11^th 2025

Our Coherent Sensing Lab 4 is now equipped with two optical tables!

Big thanks to Rupert, Christoph, Werner, Adrian, Armin, Elias, Robert and Mithun for implementing the ~ 1 ton optical tables! The Coherent Sensing Lab 4 is ready for spectroscopic equipment.😊

January 2025

Visit from Lille

Arno Mussot from the University of Lille, France, visited us with his postdoctoral fellow Debanuj Chatterjee and some fibers for spectral broadening and pulse compression for the next level of ultra broadband dual comb spectroscopy.

Thanks, Arno and Deb, for your visit! We had lots of fun with you in the lab and in the Wirtshaus!😊

December 2024

Full house with Ferenc Krausz

Nobel laureate Ferenc Krausz visited Graz and the IEP in December 2024. We were so proud while giving him a lab tour! This exceptional day peaked in Ferenc’s inspiring evening talk “Sub-atomic motions probe human health”, this year’s BioTechMed Nobel lecture. We counted more than 500 visitors, our grand lecture hall P1 was too small for so many science enthusiasts.

Thank you so much for coming!

Nobelpreisträger Prof. Ferenc Krausz , Noble Lecture an der TU Graz

Nobelpreisträger Prof. Ferenc Krausz , Noble Lecture an der TU Graz

September 23^rd2024

Wolf Outstanding Student Paper Prize

Lukas receives the Wolf Student Paper Prize at the Frontiers in Optics (FIO) Conference in Denver for the work entitled

"Near-ultraviolet Dual-comb Spectroscopy / Absolute Absorption Cross Section of Formaldehyde"

Congratulations, Lukas!

July 2024

Christoph GRUBER joins our team

Herzlich Willkommen, Christoph!

April 10^th2024

Our novel broadband UV dual comb spectrometer becomes official!

Congratulations, Lukas!

The world’s first broadband UV dual comb spectrometer revolutionizes air pollutant analysis. It enables real-time tracking of pollutants and their reactions with the environment. The work got now published in OPTICA.

Check out more details
Press release:
Novel UV Broadband Spectrometer Revolutionises Air Pollutand Analysis

Puplication:
Broadband near-ultraviolet dual comb spectroscopy

NAWI Graz, Kooperation zwischen TU Graz und KF Universität Graz — © Lunghammer

February 12^th2024

The work of our first field deployed dual comb spectrometer got published!

Congratulations, Alex!

We successfully tracked the concentration of nitrogen dioxide in the city of Graz. We achieved a temporal resolution of one minute and a detection sensitivity of only 5 ppb.
To our knowledge, this is the first mobile dual comb spectrometer capable of measuring NO2.

Check out more details:
Coherent field sensing of nitrogen dioxide (optica.org)

February 8^th2024

Dual Poster Presentation on Dual Comb Spectroscopy

Armin and Elias show their posters in parallel on this year`s first DocDay!

January 29^th2024

Coherent Sensing Group meets Anne L’Huillier

Group Excursion to the Austrian Academy of Sciences (ÖAW) in Vienna for this year’s ISTA Lecture:
Anne L’Huillier talked about “Attosecond Pulses For Studying Ultrafast Electron Dynamics”. The most important step towards attosecond pulses is high harmonic generation that has been studied extensively by Anne L’Huillier and that plays also a crucial part in our Project ELFIS, funded by the ERC.

January 26^th2024

Coherent Sensing Group visits Ball der Technik

Part of the team entered “one of the nicest balls of Austria”!

If you are interested in older news, visit our "News Archive"!

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)
https://doi.org/10.1038/nphoton.2009.217

[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)
https://doi.org/10.1038/nature12607

[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)
https://doi.org/10.1364/OL.37.004498

[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)
https://doi.org/10.1364/OL.37.000503

[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)
https://doi.org/10.1103/PhysRevA.89.023408

[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)
https://doi.org/10.1038/s41467-018-03122-1

[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)
https://doi.org/10.1364/OE.424940

[8] A. Eber, et al., Coherent field sensing of nitrogen dioxide, Opt Express 32, 6575 (2024)
https://doi.org/10.1364/OE.513523

[9] Fürst, Lukas, et al., Broadband near-ultraviolet dual comb spectroscopy, Optica 11.4, 471-477 (2024)
https://doi.org/10.1364/OPTICA.516783

Funding

All images © TU Graz/Institute of Experimental Physics

Content

Contact

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

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

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

bernhardt@tugraz.at

Group Members

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

BSc DI Alexander EBER alexander.ebernoSpam@tugraz.at +43 (316) 873-8152
BSc MSc Lukas FÜRST lukas.fuerstnoSpam@tugraz.at +43 (316) 873-8928
BSc MSc Adrian KIRCHNER adrian.kirchnernoSpam@tugraz.at +43 (316) 873-8147
BSc DI Robert DI VORA divoranoSpam@tugraz.at +43 (316) 873-8146
BSc DI Armin SPELETZ armin.speletznoSpam@tugraz.at +43(316)873-8928
BSc MSc Ph D. Mithun PAL mithun.palnoSpam@tugraz.at +43(316)873-8640
BA Ph D. Emily HRUSKA emily.hruskanoSpam@tugraz.at +43(316)873-8640
BSc Florian LINDORFER florian.lindorfernoSpam@student.tugraz.at +43 (316) 873-8662
BSc MSc Elias EHL elias.ehlnoSpam@tugraz.at +43 (316) 873-8662

MSc Christoph GRUBER christoph.grubernoSpam@tugraz.at +43 (316) 873-8167

Links

Online Video / What we are up to