Generation of isolated elliptically polarized sub-100-as pulses from Ne atoms in combined chirped fields
Phys. Rev. A 112, 033110 – Published 16 September, 2025
DOI: https://doi.org/10.1103/sjy5-q3nh
Abstract
We present a method to generate an isolated elliptically polarized short attosecond pulse from the ring-current state of the Ne atom in a chirped infrared (IR) field combined with an ultraviolet (UV) field. We find that the cutoff position of the harmonic spectrum emitted from the ring-current state is extended, but the harmonic efficiency is reduced in a chirped IR field compared with a chirp-free IR field. This harmonic broadening can be well understood by the semiclassical three-step model and the quantum time-frequency analysis. By introducing a UV field into the chirped IR field with a proper chirp parameter, both the efficiency and chirality of harmonic spectrum can be improved. Our analysis indicates that the generation of the elliptically polarized harmonics can be attributed to the asymmetric emission of ionized electrons in the direction. By optimizing the laser parameters, an isolated 98-as pulse with an ellipticity up to 0.94 is obtained by the broadband elliptically polarized supercontinuum. Our approach provides an effective way to generate and control the sub-100-as isolated elliptically polarized pulses.
