%0 Journal Article
%A Chitgar, Z. M.
%A Adam, R.
%A Greb, C.
%A Lehrach, A.
%A Büscher, M.
%A Gibbon, P.
%T Theory of circularly polarized harmonic generation using bi-colour lasers in underdense plasmas
%J Plasma physics and controlled fusion
%V 63
%N 3
%@ 1361-6587
%C Bristol
%I IOP Publ.
%M FZJ-2021-01812
%P 035023 -
%D 2021
%X Circularly polarized (CP) extreme ultraviolet- and x-ray radiation is an essential tool for analyzing the magnetic properties of materials. Elliptically polarized high harmonic generation (HHG) has been demonstrated by focusing bi-chromatic (800 + 400 nm wavelengths), counter-rotating CP laser pulses into gas targets (Fleischer et al 2014 Nat. Photonics 8 543). More recent theoretical studies indicate that a bi-circular laser driver can also work in both under- and overdense plasmas with analogous selection rules to those in gases: for example, every third harmonic is suppressed and adjacent harmonics have opposite helicity for counter-polarized CP ω0 and 2ω0 pumps. In this work, an analytical theory of bi-circular HHG from underdense plasmas is formulated which provides quantitative predictions of harmonic efficiency scaling, selectivity and helicity for both co- and counter-polarized drivers of arbitrary frequency ratio. This is compared to a fully non-linear, one-dimensional fluid model and particle-in-cell simulations, showing good agreement with both.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000612935200001
%R 10.1088/1361-6587/abd9e1
%U https://juser.fz-juelich.de/record/891900