The aim of the network is to develop harmonic generation processes so that they become a useful XUV source with well characterized and understood properties.
There are three objectives :
1. to understand the basic physics governing harmonic generation in strong fields
2. to characterize the emitted radiation
3. to demonstrate the usefulness of this radiation for applications.
The physical origin of the cutoff in harmonic generation in intense laser fields has been clarified. The classical interpretation of the generation of high harmonics has been further explored, with results on the ellipticity dependence of harmonics as well as a new and simple theoretical approach. The generation of harmonics from atoms and ions and the influence of pulse shapes have been studied. Harmonic generation efficiencies between neutral and atomic systems have been compared. Control of the third harmonic conversion through laser induced continuum structure has been studied. Above threshold ionization with high repetition rates has been investigated and some harmonic generation experiments on solid targets have been performed. Angular distributions of harmonics have been studied. The results show a narrowing of the angular distributions in the cutoff region. Temporal profiles of low order harmonics have been measured showing in particular the influence of electron dispersion. Spectral profiles have been measured. A first application of harmonics in atomic spectroscopy has been demonstrated. Using the successive harmonics of a chromium doped lithium strontium aluminium fluoride (LiSAF) laser, the relative photoionization cross sections of the rare gases have been measured over the range 10 to 120 ev.
Funding SchemeCSC - Cost-sharing contracts
SW7 2BZ London
221 00 Lund
OX1 3RH Oxford