A high-intensity highly coherent soft X-ray femtosecond laser seeded by a high harmonic beam

Abstract

Synchrotrons have for decades provided invaluable sources of soft X-rays, the application of which has led to significant progress in many areas of science and technology. But future applications of soft X-rays--in structural biology, for example--anticipate the need for pulses with much shorter duration (femtoseconds) and much higher energy (millijoules) than those delivered by synchrotrons. Soft X-ray free-electron lasers should fulfil these requirements but will be limited in number; the pressure on beamtime is therefore likely to be considerable. Laser-driven soft X-ray sources offer a comparatively inexpensive and widely available alternative, but have encountered practical bottlenecks in the quest for high intensities. Here we establish and characterize a soft X-ray laser chain that shows how these bottlenecks can in principle be overcome. By combining the high optical quality available from high-harmonic laser sources (as a seed beam) with a highly energetic soft X-ray laser plasma amplifier, we produce a tabletop soft X-ray femtosecond laser operating at 10 Hz and exhibiting full saturation, high energy, high coherence and full polarization. This technique should be readily applicable on all existing laser-driven soft X-ray facilities.

High-Brightness Injection-Seeded Soft-X-Ray-Laser Amplifier Using a Solid Target

“…However, the self-amplification of spontaneous emission in the much denser laser-created plasmas required to generate soft-x-ray-laser beams at shorter wavelengths generates beams of limited spatial coherence [5]. To overcome this limitation, seeding of the soft-x-ray-laser amplifier with either the spatially filtered radiation from a second soft-x-ray amplifier [6,7] or with a high harmonic of an optical laser has been investigated [8][9][10]. The latter scheme has the advantage of producing significantly shorter (subpicosecond) laser pulses and also requires less laser pump energy to generate the seed pulse.…”

“…The latter scheme has the advantage of producing significantly shorter (subpicosecond) laser pulses and also requires less laser pump energy to generate the seed pulse. Saturated amplification of the 25th harmonic of a Ti:sapphire (Ti:Sa) laser was recently demonstrated in a 32.8 nm Ni-like Kr optical field ionization (OFI) softx-ray-laser amplifier [9]. However, the comparatively low plasma density ( < 1 10 19 cm ÿ3 ) at which optimum lasing occurs in these OFI lasers results in a relatively low saturation intensity and narrow bandwidth that will ultimately limit the maximum brightness possible using that scheme.…”

Cohérence temporelle et largeur spectrale des lasers XUV transitoires pompés en incidence rasante

“…L'injection d'harmoniques laser d'ordre éleve HOH dans un laser X constitue l'un des progrès les plus significatifs obtenus [1]. Plusieurs points restent toutefois à améliorer pour que le laser X rivalise avec les harmoniques d'ordre élevé ou les lasers X à électrons libres (XFEL).…”

XUV digital in-line holography using high-order harmonics

“…Examples of this development are the effort to build X-ray free electron lasers at various places in the world [1] and to develop seeded soft-x-ray lasers [2]. One of the first experiments performed at FLASH, XUV-free electron laser facility in Hamburg is timeresolved X-ray holography using a clever single-shot design [3].…”