Polarization of high-order harmonics

摘要: We report measurements and calculations of the polarization state high-order harmonics generated by a 790-nm Ti:sapphire laser. The problem completely characterizing partially polarized radiation in XUV range is discussed detail. comparison between several gases, xenon, argon neon, different orders, from 17th to 33rd, shows that rotation angle ellipticity strongly depends on position harmonic spectrum, particular, whether it cutoff or plateau. In plateau, quite large, follows fundamental, remaining, however, smaller. only polarized. contrast, cutoff, both remain small, independently laser ellipticity. Our experimental results compare well with theoretical predictions including single-atom response propagation effects.