SALT
High-Flux Synchrotron Alternatives Driven by Powerful Long-Wavelength Fiber Lasers
Prof. J. Limpert at his laboratory in spring 2019
The SALT project aimed to develop high-flux, table-top alternatives to synchrotrons in three specific spectral regions: THz, mid-IR, and soft X-rays, using frequency conversion of a high-power solid-state laser. Two major objectives were pursued: (A) improving the performance of ultrafast lasers at 2µm wavelength by exploiting Thulium-doped fiber lasers and (B) demonstrating enhanced flux in selected wavelength regions through frequency conversion of these 2 μm sources.
Key results include:
- Thulium-doped fiber CPA systems: Record average power of 1060 W was achieved at 80 MHz repetition rate and 265 fs pulse duration, outperforming Ytterbium-doped fiber lasers. [1]
- Coherent beam combination to 2 µm wavelength: A 4-channel, coherently combined Tm laser delivered 1.8 mJ pulses at 180 W average output power at 100 kHz repetition rate with excellent beam quality [2]. The output pulse duration can be as short as 85 fs. This is the current average power record for mJ-class ultrafast laser systems around the 2 µm region to date.
- Two approaches for pulse post-compression at 2 µm wavelength have been successfully pursued: a gas-filled capillary as well as a gas-filled multipass-cell for spectral broadening. We have been able to demonstrate nonlinear pulse compression down to 10.2 fs duration at pulse energies >1.3 mJ and average powers >130 W in a gas-filled capillary [3].
- THz generation: the THz generation builds on the record power demonstration with a 1 µm Ytterbium-based drive laser and could be made usable at 2 µm wavelength as well. A significant conversion efficiency enhancement with the doubled drive wavelength in a gas-plasma based THz generation could be demonstrated. The outcome was an average power of 380 mW of broadband, single-cycle THz pulses with an efficiency as high as 0.32% which is roughly a factor 4 higher than previously reported for a 1 µm drive wavelength [4]. This result will open new possibilities for THz applications which rely on highest flux levels.
- Mid-IR generation: an increase in efficiency was achieved with longer non-linear crystals through intra-pulse difference frequency generation in GaSe crystals with a conversion efficiency of up to 6 % (from 2 µm to 5-15 µm). Further power scaling is in progress.
- Soft X-ray generation: High-harmonic generation (HHG) experiments demonstrated photon energies up to 400 eV using few-cycle pulses, providing the groundwork for applications such as high-resolution biological imaging [5, 6].
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References
[1] C. Gaida, M. Gebhardt, T. Heuermann, F. Stutzki, C. Jauregui, J. Limpert, "Ultrafast thulium fiber laser system emitting more than 1 kW of average power," Opt. Lett. 43, 5853-5856 (2018).
[2] T. Heuermann, Z. Wang, M. Lenski, M. Gebhardt, C. Gaida, M. Abdelaal, J. Buldt, M. Müller, A. Klenke, J. Limpert, "Ultrafast Tm-doped fiber laser system delivering 1.65-mJ, sub-100-fs pulses at a 100-kHz repetition rate," Opt. Lett. 47, 3095-3098 (2022)
and/or
T. Heuermann, Z. Wang, M. Lenski, M. Gebhardt, C. Gaida, M. Abdelaal, J. Buldt, M. Müller, A. Klenke, J. Limpert, "188 W average power coherently combined Tm-doped fiber laser system delivering ultrashort pulses with 1.86 mJ energy," Proc. SPIE 12400, Fiber Lasers XX: Technology and Systems, 124000E (8 March 2023); https://doi.org/10.1117/12.2650327
[3] Z. Wang, T. Heuermann, M. Gebhardt, M. Lenski, P. Gierschke, R. Klas, J. Rothhardt, C. Jauregui, and J. Limpert, "Nonlinear pulse compression to sub-two-cycle, 1.3 mJ pulses at 1.9 μm wavelength with 132 W average power," Opt. Lett. 48, 2647-2650 (2023)
[4] J. Buldt, T. Heuermann, Z. Wang, P. Gierschke, M. Lenski, C. Jauregui, J. Limpert, "High-power two-color plasma-based THz generation driven by a Tm-doped fiber laser," Opt. Lett. 48, 3403-3406 (2023)
[5] M. Gebhardt, T. Heuermann, R. Klas, C. Liu, A. Kirsche, M. Lenski, Z. Wang, C. Gaida, J. Antonio-Loped, A. Schülzgen, R. Amezcua-Correa, J. Rothhardt, J. Limpert, ”Bright, high-repetition-rate water window soft X-ray source enabled by nonlinear pulse self-compression in an antiresonant hollow-core fibre,” Light: Science and Applications 10, 36 (2021)
[6] J. Rothhardt, W. Eschen, C. Liu, D. Penagos, R. Klas, P. Gierschke, Z. Wang, M. Karst, J. Limpert, „Imaging with High Average Power High-Harmonic EUV and Soft-X-ray Sources (invited talk) “High Intensity Lasers and High Field Phenomena, ETu6A.1, 12.03.2024, Vienna, Austria
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Publications
Joachim Buldt, Michael Mueller, Henning Stark, Cesar Jauregui, Jens Limpert, Fiber laser-driven gas plasma-based generation of THz radiation with 50-mW average power, Applied Physics B, 126/1, 2020, 10.1007/s00340-019-7353-2External link
Albrecht Steinkopff, Cesar Jauregui, Christopher Aleshire, Arno Klenke, Jens Limpert, Impact of thermo-optical effects in coherently combined multicore fiber amplifiers, Optics Express, 28 (25), 2020, 10.1364/oe.410614External link
Christian Grebing, Michael Müller, Joachim Buldt, Henning Stark, Jens Limpert, Kilowatt-average-power compression of millijoule pulses in a gas-filled multi-pass cell, Optics Letters, 45 (22), 2020, 10.1364/ol.408998External link
E. Shestaev, S. Hädrich, N. Walther, T. Eidam, A. Klenke, I. Seres, Z. Bengery, P. Jójárt, Z. Várallyay, Á. Börzsönyi, J. Limpert, Carrier-envelope offset stable, coherently combined ytterbium-doped fiber CPA delivering 1 kW of average power, Optics Letters, 45 (23), 2020, 10.1364/ol.409410External link
W. Eschen, S. Wang, C. Liu, R. Klas, M. Steinert, S. Yulin, H. Meißner, M. Bussmann, T. Pertsch, J. Limpert, and J. Rothhardt, Towards attosecond imaging at the nanoscale using broadband holography-assisted coherent imaging in the extreme ultraviolet, Communications Physics, 4 (154), 2021, 10.1038/s42005-021-00658-5External link
M. Gebhardt, T. Heuermann, R. Klas, C. Liu, A. Kirsche, M. Lenski, Z. Wang, C. Gaida, J. E. Antonio-Lopez, A. Schülzgen, R. Amezcua-Correa, J. Rothhardt, J. Limpert, Bright, high-repetition-rate water window soft X-ray source enabled by nonlinear pulse self-compression in an antiresonant hollow-core fibre, Light: Science & Applications, 10/1, 2021, 10.1038/s41377-021-00477-xExternal link
Martin Gebhardt, Emmanuel B. Amuah, Robert Klas, Henning Stark, Joachim Buldt, Albrecht Steinkopff, Jens Limpert, Investigation of spatiotemporal output beam profile instabilities from differentially pumped capillaries, Optics Express, 29 (5), 2021, 10.1364/oe.416553External link
Christian Gaida, Martin Gebhardt, Tobias Heuermann, Ziyao Wang, Cesar Jauregui, Jens Limpert, Transverse mode instability and thermal effects in thulium-doped fiber amplifiers under high thermal loads, Optics Express, 29 (10), 2021, 10.1364/oe.421954External link
Michael Müller, Christopher Aleshire, Joachim Buldt, Henning Stark, Christian Grebing, Arno Klenke, Jens Limpert, Scaling potential of beam-splitter-based coherent beam combination, Optics Express, 29 (17), 2021, 10.1364/oe.433596External link
Schuster, V., V. Hilbert, R. Klas, C. Liu, M. Tschernajew, B. Bernhardt, J. Rothhardt, J. Limpert, Agile spectral tuning of high order harmonics by interference of two driving pulses, Optics Express, 29 (14), 2021, 10.1364/oe.424024External link
H. Stark, J. Buldt, M. Mueller, A. Klenke, J. Limpert, 1 kW, 10 mJ, 120 fs coherently combined fiberCPA laser system, Optics Letters, 46 (5), 2021, 10.1364/ol.417032External link
Michael Müller, Joachim Buldt, Henning Stark, Christian Grebing, Jens Limpert, Multipass cell for high-power few-cycle compression, Optics Letters, 46 (11), 2021, 10.1364/ol.425872External link
Joachim Buldt, Henning Stark, Michael Müller, Christian Grebing, César Jauregui, Jens Limpert, Gas-plasma-based generation of broadband terahertz radiation with 640 mW average power, Optics Letters, 46 (20), 2021, 10.1364/ol.442374External link
Henning Stark, Christian Grebing, Joachim Buldt, Arno Klenke, Jens Limpert, Divided-pulse nonlinear compression in a multipass cell, JPhys photonics , 4(3), 2022, 10.1088/2515-7647/ac66abExternal link
Eschen, Wilhelm, Lötgering, Lars, Schuster, Vittoria, Klas, Robert, Kirsche, Alexander, Berthold, Lutz, Steinert, Michael, Pertsch, Thomas, Gross, Herbert, Krause, Michael, Limpert, Jens, Rothhardt, Jan, Material-specific high-resolution table-top extreme ultraviolet microscopy, Light: Science & Applications, 11 (1), 2022, 10.1038/s41377-022-00797-6External link
Albrecht Steinkopff, Christopher Aleshire, Arno Klenke, Cesar Jauregui, Jens Limpert, Mitigation of thermally-induced performance limitations in coherently-combined multicore fiber amplifiers, Optics Express, 30(10), 2022, 10.1364/oe.451690External link
Loetgering, L., S. Witte, J. Rothhardt, Advances in laboratory-scale ptychography using high harmonic sources, Optics Express, 30 (3), 2022, 10.1364/oe.443622External link
Mathias Lenski, Tobias Heuermann, Martin Gebhardt, Ziyao Wang, Christian Gaida, César Jauregui, Jens Limpert, Inband-pumped, high-power thulium-doped fiber amplifiers for an ultrafast pulsed operation, Optics Express, 30(24), 2022, 10.1364/oe.476160External link
Christopher Aleshire, Albrecht Steinkopff, Arno Klenke, César Jáuregui, Stefan Kuhn, Johannes Nold, Nicoletta Haarlammert, Thomas Schreiber, Jens Limpert, High-energy Q-switched 16-core tapered rod-type fiber laser system, Optics Letters, 47(7), 2022, 10.1364/ol.454287External link
Arno Klenke, Albrecht Steinkopff, Christopher Aleshire, Cesar Jauregui, Stefan Kuhn, Johannes Nold, Christian Hupel, Sigrun Hein, Steffen Schulze, Nicoletta Haarlammert, Thomas Schreiber, Andreas Tünnermann, Jens Limpert, 500 W rod-type 4 × 4 multicore ultrafast fiber laser, Optics Letters, 47 (2), 2022, 10.1364/ol.445302External link
Steffen Hädrich, Evgeny Shestaev, Maxim Tschernajew, Fabian Stutzki, Nico Walther, Florian Just, Marco Kienel, Imre Seres, Péter Jójárt, Zsolt Bengery, Barnabás Gilicze, Zoltán Várallyay, Ádám Börzsönyi, Michael Müller, Christian Grebing, Arno Klenke, Dominik Hoff, Gerhard G. Paulus, Tino Eidam, Jens Limpert, Carrier-envelope phase stable few-cycle laser system delivering more than 100 W, 1 mJ, sub-2-cycle pulses, Optics Letters, 47 (6), 2022, 10.1364/ol.450991External link
Tobias Heuermann, Ziyao Wang, Mathias Lenski, Martin Gebhardt, Christian Gaida, Mahmoud Abdelaal, Joachim Buldt, Michael Müller, Arno Klenke, Jens Limpert, Ultrafast Tm-doped fiber laser system delivering 1.65-mJ, sub-100-fs pulses at a 100-kHz repetition rate, Optics Letters, 47 (12), 2022, 10.1364/ol.459385External link
P. Gierschke, C. Grebing, M. Abdelaal, M. Lenski, J. Buldt, Z. Wang, T. Heuermann, M. Mueller, M. Gebhardt, J. Rothhardt, J. Limpert, Nonlinear pulse compression to 51-W average power GW-class 35-fs pulses at 2-µm wavelength in a gas-filled multi-pass cell, Optics Letters , 47(14), 2022, 10.1364/ol.462647External link
Maximilian Benner, Maximilian Karst, Cristina Amaya Mendez, Henning Stark, Jens Limpert, Concept of enhanced frequency chirping for multi-pass cells to improve the pulse contrast, Journal of the Optical Society of America / B, 40(2), 2023, 10.1364/josab.479037External link
Alexander Kirsche, Martin Gebhardt, Robert Klas, Lucas Eisenbach, Wilhelm Eschen, Joachim Buldt, Henning Stark, Jan Rothhardt, Jens Limpert, Continuously tunable high photon flux high harmonic source, Optics Express, 31(2), 2023, 10.1364/oe.474668External link
Albrecht Steinkopff, Christopher Aleshire, Arno Klenke, Cesar Jauregui, Jens Limpert, Analysis of optical core-to-core coupling: challenges and opportunities in multicore fiber amplifiers, Optics Express, 31(17), 2023, 10.1364/oe.498460External link
Lars Loetgering, Mengqi Du, Dirk Boonzajer Flaes, Tomas Aidukas, Felix Wechsler, Daniel S. Penagos Molina, Max Rose, Antonios Pelekanidis, Wilhelm Eschen, Jürgen Hess, Thomas Wilhein, Rainer Heintzmann, Jan Rothhardt, Stefan Witte, PtyLab.m/py/jl: a cross-platform, open-source inverse modeling toolbox for conventional and Fourier ptychography, Optics Express, 31 (9), 2023, 10.1364/oe.485370External link
Henning Stark, Maximilian Benner, Joachim Buldt, Arno Klenke, Jens Limpert, Pulses of 32 mJ and 158 fs at 20-kHz repetition rate from a spatiotemporally combined fiber laser system, Optics Letters , 48 (11), 2023, 10.1364/ol.488617External link
Ziyao Wang, Tobias Heuermann, Martin Gebhardt, Mathias Lenski, Philipp Gierschke, Robert Klas, Jan Rothhardt, Cesar Jauregui, Jens Limpert, Nonlinear pulse compression to sub-two-cycle, 1.3 mJ pulses at 1.9 μm wavelength with 132 W average power, Optics Letters, 48 (10), 2023, 10.1364/ol.487587External link
Karst, M., Benner, M., Gierschke, P., Stark, H., Limpert, J., Dispersion engineering in nonlinear multipass cells for high-quality pulse compression, Optics Letters , 48 (22), 2023, 10.1364/ol.504014External link
Karst, M., Pfaller, P., Klas, R., Wang, Z. Y., Gierschke, P., Rothhardt, J., Limpert, J., 22-W average power high pulse energy multipass-cell-based post-compression in the green spectral range, Optics Letters , 48 (5), 2023, 10.1364/ol.482600External link
Christopher Aleshire, Timo Eichner, Albrecht Steinkopff, Arno Klenke, Cesar Jauregui, Guido Palmer, Stefan Kuhn, Johannes nold, Nicoletta Haarlammert, Wim P. Leemans, Thomas Schreiber, Andreas R. Maier, Jens Limpert, Frequency-doubled Q-switched 4 × 4 multicore fiber laser system, Optics Letters , 48(8), 2023, 10.1364/ol.487334External link
Joachim Buldt, Tobias Heuermann, Ziyao Wang, Philipp Gierschke, Mathias Lenski, César Jauregui, Jens Limpert, High-power two-color plasma-based THz generation driven by a Tm-doped fiber laser, Optics Letters , 48(13), 2023, 10.1364/ol.492511External link
Lucas Eisenbach, Ziyao Wang, Jan Schulte, Tobias Heuermann, Peter Russbüldt, Rudolf Meyer, Philipp Gierschke, Mathias Lenski, Muneo Sugiura, Koichi Tamura, Jens Limpert and Constantin Häfner, Highly efficient nonlinear compression of mJ pulses at 2 µm wavelength to 20 fs in a gas-filled multi-pass cell , Journal of Physics: Photonics, 6 (3), 2024, 10.1088/2515-7647/ad4cc4
Theses:
Michael Müller, The Scaling Limits of Beam-Splitter-Based Coherent Beam Combining
Robert Klas, Development of tailored XUV sources for applications in Laser spectroscopy and imaging experiments
Martin Gebhardt, Power scaling of few-cycle short-wavelength infrared laser sources for nonlinear frequency conversion
Conference Contributions
Tobias Heuermann, Ziyao Wang, Mathias Lenski, Martin Gebhardt, Christian Gaida, Mahmoud Abdelaal, Joachim Buldt, Michael Müller, Arno Klenke, Jens Limpert, 188 W average power coherently combined Tm-doped fiber laser system delivering ultrashort pulses with 1.86 mJ energy, Proc. SPIE 12400, Fiber Lasers XX: Technology and Systems, 124000E, https://doi.org/10.1117/12.2650327External link
Lucas Eisenbach, Peter Rußbüldt, Jan Schulte, Rudolf Meyer, Tobias Heuermann, Ziyao Wang, Mathias Lenski, Philipp Gierschke, Jens Limpert, Constantin Häfner, Highly efficient nonlinear spectral broadening of mJ pulses at 2µm wavelength in a gas multipass cell and compression sub-30 fs, Proc. SPIE PC12577, High-power, High-energy Lasers and Ultrafast Optical Technologies, PC125770E
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Awards and recognitions
2024
Jens Limpert, Jan Rothhardt
EPS-QEOD Prize for Research in Laser Science and Applications, European Physical Society
New insights and technologies for the realisation of benchtop extreme ultraviolet sources with synchrotron-like brilliance2023
Heuermann, Tobias
3rd Place Best Student Presentation Award, SPIE. Photonics West
Scaling of ultrafast thulium-doped fiber laser systems using coherent beam combination of large mode area fiber amplifiersKlas, Robert
3rd Place Hugo Geiger Award
Fraunhofergesellschaft & Bayrisches WirtschaftsministeriumJens Limpert, Thomas Pertsch, Jan Rothhardt
Wissenschaftspreis für „Exzellente interdisziplinäre Kooperation“, Beutenberg-Campus Jena e.V.
Neuartige Mikroskopie im extremen Ultraviolett enthüllt Nanowelt der Mikroorganismen2022
Gebhardt, Martin
Friedrich-Hund-Dissertationspreis für Angewandte Forschung, Physikalisch-Astronomische Fakultät
Power scaling of few-cycle short-wavelength infrared laser sources for nonlinear frequency conversionTu, Yiming
2nd Place Best Student Paper Award, SPIE. Photonics West
Real-time modal decomposition of fiber laser beams using a spatial mode multiplexer2021
Klas, Robert
SPARC PhD-Prize, Helmholtzzentrum für Schwerionenforschung (GSI)
Efficiency Scaling of High Harmonic Generation using Ultrashort Fiber Lasers2020
Gebhardt, Martin
1st Place: Best Student Paper, SPIE. Photonics West
Soft x-ray high order harmonic generation driven by high repetition rate ultrafast thulium-doped fiber lasersKlas, Robert
OSA Student Paper Award, OSA Laser Congress
Sub-20 fs High-energy Pulse generation at 515 nm with 50 W of Average PowerMüller Michael
2nd Place: Best Student Paper ", SPIE. Photonics West
10.4 kW coherently-combined ultrafast fiber laser
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ERC Advanced Grant -
(No. 835306)
Information
Prof. Jens Limpert was one of the first to obtain not only a "Starting Grant" (2009) but also a "Consolidator Grant" (2014) and now the "Advanced Grant". In Germany he is even the only one with such a "series".