Enhanced Generation of Angularly Separated Elliptical Harmonics

We propose and numerically demonstrate a novel scheme that synergistically combines a linearly polarized (LP) driving laser with a second circularly polarized (CP) laser to generate angularly separated elliptical harmonics carrying tunable spin angular momentum. The LP laser component dramatically boosts the high-order harmonic generation (HHG) efficiency, while the CP component imprints its spin angular momentum onto the harmonics, which are then diffracted from the periodically modulated microstructured target surface, with their emission angles precisely determined by grating diffraction theory. Particle-in-cell (PIC) simulations confirm that the HHG yield is enhanced by three orders of magnitude compared to the pure CP case. Moreover, the HHG ellipticity and intensity can be effectively controlled via the CP laser’s intensity and incidence angle. This work provides a feasible table-top route towards angularly separated, high-intensity, polarization-controllable extreme ultraviolet sources for various advanced applications.