Towards Extreme VUV by Harmonic Generation in Strong Fields

Abstract

Most of experiments on harmonic generation in a gaseous medium use short incident wavelengths in order to obtain the shortest generated wavelengths1−4. McPherson et al have reported up to the 17th harmonic in Ne using a 248 nm (KrF) excimer laser4 at an intensity of 1016 W/cm2. This radiation corresponds to the emission of a photon around 15 nm, or a photon energy of 85 eV. It has been demonstrated5,6 that high-order harmonics can be produced in a rare gas medium with laser photon energies more than 10 times smaller than the ionization energy.