Elliptically polarized isolated attosecond pulse generation from atom in inhomogeneous linear laser fields

Elliptically polarized attosecond pulse has significant applications to study the ultrafast chiral dynamics and X-ray magnetic circular dichroism (XMCD) due to its ultrashort time-scale (attosecond) and elliptical polarization characteristics. In our study, the interaction between the inhomogeneous linear laser field and the Ne atoms is simulated by numerically solving the time-dependent Schrödinger equation. Specifically, the influences of the inhomogeneity of the driving field and the orbital angular momentum (OAM) of the initial orbital on high-order harmonics (HH) and attosecond pulses are revealed. HH generated by the linear laser fields with different inhomogeneity are calculated. The results indicate that the inhomogeneity 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- orbital) leads to elliptically polarized emission. Thiz study provides a theoretical foundation for generating and controlling elliptically polarized isolated attosecond pulses using inhomogeneous linearly polarized laser fields, offering new possibilities for ultrafast spectroscopy and magnetic material characterization.