Orbital angular momentum mode selection by rotationally symmetric superposition of chiral states with application to electron vortex beams

TL;DR

This paper introduces a general principle for selecting orbital angular momentum modes through rotationally symmetric superpositions of chiral states, enabling systematic generation of structured OAM waves, demonstrated with electron vortex beams.

Contribution

It presents a novel OAM mode selection principle based on rotationally symmetric superpositions, applicable to electron vortex beams and other structured wave generation.

Findings

The principle explains spiral zone plate hologram operation.

Rotationally symmetric patterns can generate vortex beams.

Experimental validation with electron vortex beams using chiral masks.

Abstract

A general orbital angular momentum (OAM) mode selection principle is put forward involving the rotationally symmetric superposition of chiral states. This principle is not only capable of explaining the operation of spiral zone plate holograms and suggesting that naturally occurring rotationally symmetric patterns could be inadvertent sources of vortex beams, but more importantly, it enables the systematic and flexible generation of structured OAM waves in general. This is demonstrated both experimentally and theoretically in the context of electron vortex beams using rotationally symmetric binary amplitude chiral sieve masks.