Harmonic Emission from the Rear Side of Thin Overdense Foils Irradiated with Intense Ultrashort Laser Pulses

The harmonic emission from thin solid carbon and aluminum foils, irradiated by 150 fs long frequency-doubled Ti:sapphire laser pulses at \ensuremath{\lambda}=395\text{ }\text{ }\mathrm{nm}and peak intensities of a few {10}^{18}\text{ }\mathrm{W}/{\mathrm{cm}}^{2} has been studied. In addition to the harmonics emitted from the front side in the specular direction, we observe harmonics up to the 10th order, including the fundamental from the...