| 1. |
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| 2. |
- Balla, Prannay, et al.
(author)
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Post-compression of picosecond pulses to four optical cycles
- 2020
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In: High Intensity Lasers and High Field Phenomena, HILAS 2020. - 9781557528209
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Conference paper (peer-reviewed)abstract
- We report post-compression of 1.2 ps pulses into the few-cycle regime via multi-pass spectral broadening. We achieve compression factors of 40 in single and 93 in a dual stage scheme using a compact setup.
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| 3. |
- Balla, Prannay, et al.
(author)
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Postcompression of picosecond pulses into the few-cycle regime
- 2020
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In: Optics Letters. - 0146-9592. ; 45:9, s. 2572-2575
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Journal article (peer-reviewed)abstract
- In this work,we demonstrate postcompression of 1.2 ps laser pulses to 13 fs via gas-based multipass spectral broadening. Our results yield a single-stage compression factor of about 40 at 200 W in-burst average power and a total compression factor >90 at reduced power. The employed scheme represents a route toward compact few-cycle sources driven by industrial-grade Yb:YAG lasers at high average power.
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| 4. |
- Escoto, Esmerando, et al.
(author)
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Role of dispersion and compression ratio on the temporal contrast of SPM-broadened post-compressed pulses
- 2021
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In: 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021. - 9781665418768
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Conference paper (peer-reviewed)abstract
- Nonlinear pulse post-compression, mainly enabled by self-phase modulation (SPM), opens new avenues towards high peak power laser pulses at high average power while bypassing the need for a gain medium with large bandwidth. However, SPM-induced spectral broadening typically introduces spectral amplitude modulations as well as a chirp of third and higher orders, limiting the temporal contrast of the compressed pulse. While some recent works address this issue and discuss mitigation strategies [1] , [2] , not much attention has been devoted to the physical processes and limitations that determine the temporal contrast of post-compressed pulses. As novel compression techniques expand the achievable compression ratio [3] , it is increasingly important to fully understand the underlying pulse quality limitations. Here, we outline the role of two important characteristics - dispersion and compression ratio - on the temporal quality of post-compressed pulses. Using both numerical simulations as well as experimental tests employing a gas-filled multi-pass cell (MPC), we study the temporal contrast of post-compressed pulses over large compression-ratio and dispersion range. Using a 730 fs input pulse we were able to generate a 55 fs post-compressed pulse with up to 78% energy contained in the main compressed pulse (defined via the first local minima near the highest peak) against its picosecond background.
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| 5. |
- Heyl, Christoph M., et al.
(author)
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High-energy bow tie multi-pass cells for nonlinear spectral broadening applications
- 2022
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In: JPhys Photonics. - : IOP Publishing. - 2515-7647. ; 4:1
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Journal article (peer-reviewed)abstract
- Multi-pass cells (MPCs) have emerged as very attractive tools for spectral broadening and post-compression applications. We discuss pulse energy limitations of standard MPCs considering basic geometrical scaling principles and introduce a novel energy scaling method using a MPC arranged in a bow tie geometry. Employing nonlinear pulse propagation simulations, we numerically demonstrate the compression of 125 mJ, 1 ps pulses to 50 fs using a compact 2 m long setup and outline routes to extend our approach into the Joule-regime.
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| 6. |
- Heyl, Christoph M., et al.
(author)
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Pulse energy scaling of multi-pass cells for nonlinear spectral broadening applications
- 2022
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In: CLEO : Science and Innovations, S and I 2022 - Science and Innovations, S and I 2022. - 9781557528209
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Conference paper (peer-reviewed)abstract
- We discuss basic pulse energy scaling principles for multi-pass cells (MPCs) and introduce a novel multi-pass cell type which we employ to numerically predictpost-compression of 125 mJ pulses using a 2 m setup.
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| 7. |
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| 8. |
- Raab, Ann Kathrin, et al.
(author)
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Multi-gigawatt peak power post-compression in a bulk multi-pass cell at a high repetition rate
- 2022
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In: Optics Letters. - 0146-9592. ; 47:19, s. 5084-5087
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Journal article (peer-reviewed)abstract
- The output of a 200 kHz, 34 W, 300 fs ytterbium amplifier is compressed to 31 fs with >88% efficiency to reach a peak power of 2.5 GW, which to date is a record for a single-stage bulk multi-pass cell. Despite operation 80 times above the critical power for self-focusing in bulk material, the setup demonstrates excellent preservation of the input beam quality. Extensive beam and pulse characterizations are performed to show that the compressed pulses are promising drivers for high harmonic generation and nonlinear optics in gases or solids.
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| 9. |
- Seidel, Michael, et al.
(author)
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Composition and Transformation of Dissolved Organic Matter in the Baltic Sea
- 2017
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In: Frontiers in Earth Science. - : Frontiers Media SA. - 2296-6463. ; 5
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Journal article (peer-reviewed)abstract
- The processing of terrestrial dissolved organic matter (DOM) in coastal shelf seas is an important part of the global carbon cycle, yet, it is still not well understood. One of the largest brackish shelf seas, the Baltic Sea in northern Europe, is characterized by high freshwater input from sub-arctic rivers and limited water exchange with the Atlantic Ocean via the North Sea. We studied the molecular and isotopic composition and turnover of solid-phase extractable (SPE) DOM and its transformation along the salinity and redox continuum of the Baltic Sea during spring and autumn. We applied ultrahigh-resolution mass spectrometry and other geochemical and biological approaches. Our data demonstrate a large influx of terrestrial riverine DOM, especially into the northern part of the Baltic Sea. The DOM composition in the central Baltic Sea changed seasonally and was mainly related to autochthonous production by phytoplankton in spring. Especially in the northern, river-dominated basins, a major fraction of riverine DOM was removed, likely by bio- and photo-degradation. We estimate that the removal rate of terrestrial DOM in the Baltic Sea (Bothnian Bay to the Danish Straits/Kattegat area) is 1.6-1.9 Tg C per year which is 43-51% of the total riverine input. The export of terrestrial DOM from the Danish Straits/Kattegat area toward the North Sea is 1.8-2.1 Tg C per year. Due to the long residence time of terrestrial DOMin the Baltic Sea (total of ca. 12 years), seasonal variations caused by bio- and photo-transformations and riverine discharge are dampened, resulting in a relatively invariant DOM molecular and isotopic signature exported to the North Sea. In the deep stagnant basins of the Baltic Sea, the DOM composition and dissolved organic nitrogen concentrations changed seasonally, likely because of vertical particle transport and subsequent degradation releasing DOM. DOM in the deep anoxic basins was also enriched in sulfur-containing organic molecules, pointing to abiotic sulfurization of DOM under sulfidic conditions.
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| 10. |
- Viotti, Anne Lise, et al.
(author)
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Few-cycle pulse generation by double-stage hybrid multi-pass multi-plate nonlinear pulse compression
- 2023
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In: Optics Letters. - 0146-9592. ; 48:4, s. 984-987
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Journal article (peer-reviewed)abstract
- Few-cycle pulses present an essential tool to track ultrafast dynamics in matter and drive strong field effects. To address photon-hungry applications, high average power lasers are used which, however, cannot directly provide sub-100-fs pulse durations. Post-compression of laser pulses by spectral broadening and dispersion compensation is the most efficient method to overcome this limitation. We present a notably compact setup which turns a 0.1-GW peak power, picosecond burst-mode laser into a 2.9-GW peak power, 8.2-fs source. The 120-fold pulse duration shortening is accomplished in a two-stage hybrid multi-pass, multi-plate compression setup. To our knowledge, neither shorter pulses nor higher peak powers have been reported to-date from bulk multi-pass cells alone, manifesting the power of the hybrid approach. It puts, for instance, compact, cost-efficient, and high repetition rate attosecond sources within reach.
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| 11. |
- Viotti, Anne Lise, et al.
(author)
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Intra-Burst Pulse Characterization of a High-Power Post-Compressed Yb:YAG Laser at 100 kHz Repetition Rate
- 2021
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In: 2021 Conference on Lasers and Electro-Optics Europe and European Quantum Electronics Conference, CLEO/Europe-EQEC 2021. - 9781665418768
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Conference paper (peer-reviewed)abstract
- High-average power Ytterbium (Yb) laser systems are playing an increasingly important role in ultrafast science e.g. as pump lasers for optical parametric amplifiers or directly as ultrafast sources. The gain bandwidth of Yb limits the pulse duration to a few 100 fs up to about 1 ps. However, many applications, such as attosecond physics or X-ray Free Electron Laser (FEL) science, would greatly benefit from the combination of high average powers with much shorter pulses, achievable via post-compression. Nonlinear pulse post-compression of high-average power Yb lasers employing multi-pass cell (MPC) -based spectral broadening [1], [2] was recently implemented for two burst-mode pump-probe lasers at the FEL facility FLASH in Hamburg [3], [4]. For such lasers, precise characterization and control of intra-burst pulse dynamics is crucial as the post-compression process couples input pulse energy instabilities with important output pulse parameters such as spectrum, pulse length and temporal contrast. Here, we demonstrate 100 kHz intra-burst spectrum, phase and temporal contrast characterization of a Yb:YAG Innoslab burst-mode amplifier post-compressed in a gas-filled MPC. Our measurements reveal a stable broadened spectrum and compressed pulse duration within the flat part of the burst, yielding a relative energy content of about 80% in the main compressed fs pulse (250 fs window versus 4 ps background pedestal).
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| 12. |
- Viotti, Anne Lise, et al.
(author)
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Intra-burst temporal pulse contrast of a high-power post-compressed picosecond Yb:YAG laser
- 2021
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In: Conference on Laser and Electro-Optics : Science and Innovations, CLEO:S and I 2021 - Science and Innovations, CLEO:S and I 2021. - 9781557528209
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Conference paper (peer-reviewed)abstract
- We report on pulse contrast characterization of the output of a gas-filled multi-pass cell employed for 20-fold compression of a high-power Yb:YAG laser. We demonstrate an energy content of 80% in the compressed fs pulse.
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| 13. |
- Viotti, Anne Lise, et al.
(author)
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Multi-pass cells for post-compression of ultrashort laser pulses
- 2022
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In: Optica. - 2334-2536. ; 9:2, s. 197-216
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Journal article (peer-reviewed)abstract
- Ultrafast lasers reaching extremely high powers within short fractions of time enable a plethora of applications. They grant advanced material processing capabilities, are effective drivers for secondary photon and particle sources, and reveal extreme light-matter interactions. They also supply platforms for compact accelerator technologies, with great application prospects for tumor therapy or medical diagnostics. Many of these scientific cases benefit from sources with higher average and peak powers. Following mode-locked dye and titanium-doped sapphire lasers, broadband optical parametric amplifiers have emerged as high peak- and average power ultrashort pulse lasers.Amuch more powerefficient alternative is provided by direct post-compression of high-power diode-pumped ytterbium lasers-a route that advanced to another level with the invention of a novel spectral broadening approach, the multi-pass cell technique. The method has enabled benchmark results yielding sub-50-fs pules at average powers exceeding 1 kW, has facilitated femtosecond post-compression at pulse energies above 100 mJ with large compression ratios, and supports picosecond to few-cycle pulses with compact setups. The striking progress of the technique in the past five years puts light sources with tens to hundreds of TW peak and multiple kW of average power in sight-an entirely new parameter regime for ultrafast lasers. In this review, we introduce the underlying concepts and give brief guidelines for multi-pass cell design and implementation. We then present an overview of the achieved performances with both bulk and gas-filled multipass cells.Moreover, we discuss prospective advances enabled by this method, in particular including opportunities for applications demanding ultrahigh peak-power, high repetition rate lasers such as plasma accelerators and laser-driven extreme ultraviolet sources.
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| 14. |
- Viotti, Anne Lise, et al.
(author)
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Temporal pulse quality of a Yb:YAG burst-mode laser post-compressed in a multi-pass cell
- 2021
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In: Optics Letters. - 0146-9592. ; 46:18, s. 4686-4689
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Journal article (peer-reviewed)abstract
- Nonlinear pulse post-compression represents an efficient method for ultrashort, high-quality laser pulse production. The temporal pulse quality is, however, limited by amplitude and phase modulations intrinsic to post-compression. We here characterize in frequency and time domain with high dynamic range individual post-compressed pulses within laser bursts comprising 100-kHz-rate pulse trains. We spectrally broaden 730 fs, 3.2 mJ pulses from a Yb:YAG laser in a gas-filled multi-pass cell and post-compress them to 56 fs. The pulses exhibit a nearly constant energy content of 78% in the main peak over the burst plateau, which is close to the theoretical limit. Our results demonstrate attractive pulse characteristics, making multi-pass post-compressed lasers very applicable for pump–probe spectroscopy at, e.g., free-electron lasers or as efficient drivers for secondary frequency conversion stages.
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| 15. |
- Bravo, L, et al.
(author)
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- 2021
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swepub:Mat__t
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| 16. |
- Tabiri, S, et al.
(author)
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- 2021
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swepub:Mat__t
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