Polarization control of high-harmonic generation via the spin-orbit interaction

TL;DR

This paper demonstrates how spin-orbit interaction can be used to control the polarization of high harmonics generated by atoms, revealing new ways to manipulate light at high frequencies.

Contribution

It introduces a theoretical framework showing spin-orbit interaction's role in polarization control of high-harmonic generation, supported by R-Matrix calculations.

Findings

High harmonics can be generated with specific polarization states controlled by spin-orbit interaction.

Selection rules determine the polarization of harmonics based on initial atomic states.

The phase of the initial state influences the observed harmonic polarization.

Abstract

We observe the generation of high harmonics in the plane perpendicular to the driving laser polarization and show that these are driven by the spin-orbit interaction. Using R-Matrix with time-dependence theory, we demonstrate that for certain initial states either circularly- or linearly- polarized harmonics arise via well-known selection rules between atomic states controlled by the spin-orbit interaction. Finally, we elucidate the connection between the observed harmonics and the phase of the intial state.