High-order harmonics of 248.6-nm KrF laser from helium and neon ions

Nonsequential Double Ionization of Helium

“…For relatively modest intensities it can be assumed that the ionization occurs sequentially and the atomic response can be obtained through the single active electron approach. This approach, developed first by Kulander et al, has recently been used to demonstrate the contribution of ions to the harmonic spectrum [8]. If, on the other hand, the laser intensity is sufficiently high, the electron-electron interaction can be neglected in comparison with the effect of the field, and thus the electrons ionize independently.…”

Phase-Locked High-Order Harmonic Sources

“…Although fundamental aspects of HG have been extensively studied [1], many issues regarding the use of harmonics as a practical source of high-frequency radiation remain to be explored. Efforts are being made in improving and measuring the conversion efficiency [2], in extending the available energy range [3,4], and in characterizing the properties of the harmonic radiation, spatial coherence [5], angular emission [6][7][8] and pulse duration [9,10]. In the present work, we investigate aspects related to the temporal coherence of the harmonic radiation.…”

The Edward Teller Medal Lecture: High Intensity Lasers and the Road to Ignition

“…The first was the possibility that harmonic conversion from ions rather than atoms would lead to shorter wavelength harmonics and the second was the anticipation from earlier work at wavelengths 1.05 and 0.53 micron, that a UV laser would give a higher conversion efficiency to harmonics of a given wavelength. In the event both these possibilities were successfully demonstrated, the first using the Sprite CPA laser leading to the shortest wavelength XUV harmonic with the 6.72 nm 37th harmonic of 248.6 nm from He + ions (18) and the second using the CPA beam of Titania with production of more than 10 -6 conversion into the 7th harmonic (23).…”

“…It offers near diffraction limited beams of up to 100 J energy and down to 20 ps pulse length. In parallel with these developments I was invited to set up a university research group at Oxford University and with colleagues and students from Oxford studied topics in high intensity physics including optical field ionized plasmas (17), XUV high harmonics (18) and the application of x-ray lasers to measure laser imprinted hydrodynamic perturbations of importance in direct drive ICF (19).…”