Radially and Azimuthally Polarized Few-Cycle Pulses by Post-Compression in a Multipass Cell

Radially polarized (RP) and azimuthally polarized (AP) light beams draw attention because of advantages such as breaking the diffraction limit by possessing a longitudinal electromagnetic field component in the focus [1]. Meanwhile, intense laser pulses with only few optical cycles gained high importance in the generation of isolated attosecond pulses, or in the case of particle acceleration [2,3]. Combining the vector beam properties with the few-cycle pulse duration can pave the way for new applications, like generating RP or AP isolated attosecond pulses [4]. Amplification of the ultrashort pulses generally limits the available shortest pulse duration, which can be overcome by utilizing post-compression techniques, such as noble gas filled hollow-core waveguides, thin plates or multipass cells. It was shown numerically and experimentally, that the post-compression in a multipass cell is a promising and efficient approach for high average power pulses [5]. The scalability of this technique to high energy was just recently demonstrated by experiments at the 20 mJ level, and the spectral broadening of 100 mJ pulses was also found possible [6]. RP and AP beams can be obtained by combining orthogonally polarized Hermite-Gaussian HG10 and HG01 modes, which can exist in an optical cavity. Therefore, it could be possible to extend the multipass cell technique for the spectral broadening of the RP and AP pulses to achieve few-cycle or even near single-cycle duration.