Robust carrier-envelope phase retrieval of few-cycle laser pulses

The two-dimensional momentum distributions of high-energy photoelectrons generated in the above-threshold ionization of atoms by intense laser pulses are analysed as resulting from the elastic backscattering of laser-induced returning electrons. Using this quantitative rescattering theory, we show that the returning electron wave packets are entirely determined by the properties of the laser pulses, including the absolute value of the carrier-envelope phase (CEP). We then present a robust method to precisely retrieve the absolute phase of few-cycle pulses by analysing separately the CEP dependence of the electron spectra emitted on the left and on the right directions along the laser polarization axis. In addition, our approach offers the possibility of measuring the laser peak intensity and pulse duration with an estimated error of a few per cent. (Some figures in this article are in colour only in the electronic version)