Route to intense single attosecond pulses

A feasibility study is presented for the generation of single attosecond pulses using harmonics produced by planar targets irradiated at high intensities. The investigation focuses on the interaction of a few-optical cycles, carrier-envelope phase controlled, near-infrared laser pulse with an overdense plasma. The results obtained using an one-dimensional particle-in-cell code indicate that at laser intensities of 10(20) W cm(-2) a single sub-fs pulse can be generated in the 20-70 eV spectral range with an efficiency of a few per cent and with 10(-3) to 10(-4) for higher photon energies.