TY  - JOUR
AU  - Chitgar, Z. M.
AU  - Adam, R.
AU  - Greb, C.
AU  - Lehrach, A.
AU  - Büscher, M.
AU  - Gibbon, P.
TI  - Theory of circularly polarized harmonic generation using bi-colour lasers in underdense plasmas
JO  - Plasma physics and controlled fusion
VL  - 63
IS  - 3
SN  - 1361-6587
CY  - Bristol
PB  - IOP Publ.
M1  - FZJ-2021-01812
SP  - 035023 -
PY  - 2021
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000612935200001
DO  - DOI:10.1088/1361-6587/abd9e1
UR  - https://juser.fz-juelich.de/record/891900
ER  -