Controlling the spectral shape of coherent soft X-rays

XUV digital in-line holography using high-order harmonics

“…Simultaneously, the harmonic photon flux should be improved by at least a factor of 10 to increase the signal-to-noise ratio. Promising techniques using, for example, improved phase matching [18,19] or multicolor fields [20,21] make this within reach. In the future the possibility of single-shot measurements gives this technique a great potential for imaging femtosecond processes.…”

Spatial optimization of filaments

“…Because the electric field is included in the dipole moment, one can control the harmonic generation process by arbitrarily shaping the laser pulse [84,85]. The challenge is that the electric field of the laser is not only capable of interacting with the intra-atomic process but also macroscopic phase matching can be employed for selective enhancement or suppression of single harmonics [86]. This can be understood by exciting different fiber modes in the capillary where the harmonics were generated [87,88].…”

“…Due to the long interaction range, in gas-filled hollow-core fibers mostly fairly low gas pressures p f iber ≈ 50 − 150mbar are used. Pulse shaping, especially temporal, can have a huge impact for harmonics generated in fibers because of the waveguide dispersion depending strongly on the temporal shape of the pulse [84,86,119,120,85]. Shaping of the waveguide is another approach to influence the phase-matching conditions as was successfully demonstrated [88].…”

Coherent control for the spherical symmetric box potential in short and intensive XUV laser fields

“…The spectral and temporal properties of the HHG radiation generated by this pulse can thus be influenced. This option has mainly been exploited to maximize harmonic conversion efficiency and to enhance conversion to a given harmonic [8][9][10]. More recently, as a further step towards XUV coherent control, Pfeifer et al have realized control of the branching ratio of the dissociative photoionization of sulfur hexafluoride by adaptive shaping of the HHG generating infrared field [11].…”