An optimized kHz two-colour high harmonic source for seeding free-electron lasers and plasma-based soft x-ray lasers

Lambert, Guillaume; Gautier, J.; Hauri, Christoph P.; Zeitoun, Ph.; Valentin, C.; Marchenko, T.; Tissandier, F.; Goddet, Jean-Philippe; Ribière, M.; Rey, G.; Fajardo, M.; Sebban, S.

doi:10.1088/1367-2630/11/8/083033

Cited by 50 publications

(38 citation statements)

References 27 publications

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“…An HHG light source provides temporally and spatially coherent radiation in the EUV and soft X-ray region, and its well-defined phase properties even allow the formation of single attosecond pulses or pulse trains [15,16]. Several HHG sources for seeding a free-electron laser (FEL) are discussed in the literature [17][18][19]. First seeding of an FEL using an HHG source has been demonstrated at the SPring-8 compact SASE source at 160 nm [20].…”

Section: Introductionmentioning

confidence: 99%

A high-harmonic generation source for seeding a free-electron laser at 38 nm

et al. 2013

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Direct seeding with a high-harmonic generation (HHG) source can improve the spectral, temporal, and coherence properties of a free-electron laser (FEL) and shall reduce intensity and arrival-time fluctuations. In the seeding experiment sFLASH at the extreme ultraviolet FEL in Hamburg FLASH, which operates in the selfamplified spontaneous emission mode (SASE), the 21st harmonic of an 800 nm laser is refocused into a dedicated seeding undulator. For seeding, the external light field has to overcome the noise level of SASE; therefore, an efficient coupling between seed pulse and electron bunch is mandatory. Thus, an HHG beam with a proper divergence, width, beam quality, Rayleigh length, pointing stability, single-shot pulse energy, and stability in the 21st harmonic is needed. Here, we present the setup of the HHG source that seeds sFLASH at 38.1 nm, the optimization procedures, and the necessary diagnostics.

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Section: Introductionmentioning

confidence: 99%

A high-harmonic generation source for seeding a free-electron laser at 38 nm

et al. 2013

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“…This scheme, involving only a frequency doubling crystal, was extensively investigated over the past years. In particular, it was established that harmonic pulses, containing both odd and even orders, can be generated with improved efficiency [22][23][24][25][26] compared with single-colour harmonic generation. The polarization of the harmonics, generated in such a specific case of orthogonally polarized o and 2o laser fields in a centrally symmetric gas medium, was not measured so far and was expected to be linear 27 .…”

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confidence: 99%

Towards enabling femtosecond helicity-dependent spectroscopy with high-harmonic sources

et al. 2015

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Recent advances in high-harmonic generation gave rise to soft X-ray pulses with higher intensity, shorter duration and higher photon energy. One of the remaining shortages of this source is its restriction to linear polarization, since the yield of generation of elliptically polarized high harmonics has been low so far. We here show how this limitation is overcome by using a cross-polarized two-colour laser field. With this simple technique, we reach high degrees of ellipticity (up to 75%) with efficiencies similar to classically generated linearly polarized harmonics. To demonstrate these features and to prove the capacity of our source for applications, we measure the X-ray magnetic circular dichroism (XMCD) effect of nickel at the M 2,3 absorption edge around 67 eV. There results open up the way towards femtosecond time-resolved experiments using high harmonics exploiting the powerful element-sensitive XMCD effect and resolving the ultrafast magnetization dynamics of individual components in complex materials.

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“…The seed is injected into the undulator with a set of several mirrors with an expected transmission of the whole line of about 80%. HHG will be generated in the two-colour scheme [116] enabling to deliver coherent pulses on the odd and even harmonics of this laser. The HHG seed can be transported to the undulator with a broadband spherical mirror for focussing (~10% transmission) followed by two planar mirrors for alignment (~70% transmission each), leading to a transmission of about 5%.…”

Section: A Compact Fel Line With Seeding and Echo Configurationsmentioning

confidence: 99%

Strategies towards a compact XUV free electron laser adopted for the LUNEX5 project

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et al. 2015

Journal of Modern Optics

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More than 50 years after the laser discovery, X-ray free electron lasers (FEL), the first powerful tuneable, short pulse lasers in the X-ray spectral range, are now blooming in the world, enabling new discoveries on the ultra-fast dynamics of excited systems and imaging. LUNEX5 demonstrator project aims at investigating paths towards advanced and compact FELs. Two strategies are adopted. The first one concerns the FEL line where seeding and echo harmonic generation are implemented together with compact cryogenic in-vacuum undulators. In the second one, the electron beam is no longer provided by a conventional linear accelerator but by a laser plasma process, while a necessary particular electron beam manipulation is required to handle the electron properties to enable FEL amplification.

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An optimized kHz two-colour high harmonic source for seeding free-electron lasers and plasma-based soft x-ray lasers

Cited by 50 publications

References 27 publications

A high-harmonic generation source for seeding a free-electron laser at 38 nm

A high-harmonic generation source for seeding a free-electron laser at 38 nm

Towards enabling femtosecond helicity-dependent spectroscopy with high-harmonic sources

Strategies towards a compact XUV free electron laser adopted for the LUNEX5 project

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