Generation of elliptically polarized isolated attosecond pulses from atoms driven by non-uniform linearly polarized laser fields

Elliptically polarized attosecond pulse has significant applications in studying the ultrafast chiral dynamics and X-ray magnetic circular dichroism (XMCD) due to its ultrashort time-scale (attosecond) and elliptical polarization characteristics. In this work, the interaction between the non-uniform linearly polarized laser field and the Ne atoms is simulated by numerically solving the time-dependent Schrödinger equation. Specifically, the influences of the non-uniformity of the driving field and the orbital angular momentum (OAM) of the initial orbital on high-order harmonics (HHs) and attosecond pulses are revealed. HHs generated by the linearly polarized laser fields with different non-uniformities are calculated. The results indicate that the non-uniformity significantly influences the smoothness and spectral broadening of the harmonic spectra, consequently affecting the properties of the attosecond pulses. Moreover, our findings also reveal that the OAM of the initial orbital plays a significant role in the polarization state of the attosecond pulses. When the OAM is zero (e.g., 1s orbital), the radiated attosecond pulses are linearly polarized, whereas non-zero OAM (e.g., current carrying state 2p<sub>–</sub> orbital) leads to elliptically polarized emission. This study provides a theoretical foundation for generating and controlling elliptically polarized isolated attosecond pulses by using non-uniform linearly polarized laser fields, and offers new possibilities for ultrafast spectroscopy and magnetic material characterization.