Formation and Controlling of Optical Hopfions in High Harmonic Generation

TL;DR

This paper investigates the generation of optical Hopfions in the extreme ultraviolet range through high harmonic generation involving toroidal and optical vortices, revealing novel topological structures and control mechanisms.

Contribution

It introduces a method to generate and control optical Hopfions using high harmonic generation with toroidal vortices and optical vortices, demonstrating new topological properties and control strategies.

Findings

Unique high-order topological toroidal vortex structures in harmonic spectra

Generation of optical Hopfions with distinct topological properties in EUV range

Control of topological texture and mode channeling via spin angular momentum rules

Abstract

Toroidal vortex is a kind of novel and exotic structured light with potential applications in photonic topology and quantum information. Here, we present the study on high harmonic generation (HHG) from the interaction of the intense toroidal vortices with atoms. We show that the spatial distribution of harmonic spectra reveal unique structures, which are kinds of high-order topological toroidal vortex because of the rotating of the driving fields with transverse orbital angular momentum. Then we show that, by synthesizing the toroidal vortices and optical vortices with longitudinal orbital angular momentum, it is able to generate the optical hopfions in extreme ultraviolet (EUV) range, which exhibit completely different topological property compared with both the driving fields. Harnessing the spin angular momentum selection rules, we further show that one can control the topological texture and channel each harmonic into a single mode of controllable Hopf invariant.