Manipulation of optical orbit-induced localized spin angular momentum using the periodic edge dislocation

Abstract

Orbit-induced localized spin angular momentum (OILS) has recently garnered significant attention. This paper introduces periodic edge dislocation (PED) into the tight focusing system. The study delves into the tight focusing characteristics of the radially polarized vortex plane beam with PED, demonstrating that PED serves as a straightforward and effective means of manipulating OILS, especially when both the orbital angular momentum and the polarization of the incident beam are fixed. Our findings indicate that the longitudinal OILS reaches its maximum when the difference between the period of PED and the vortex topological charge is equal to 1. Conversely, when the difference is 0, the transverse OILS reaches its maximum, while the longitudinal OILS reaches its minimum. Similar patterns are also observed in linearly polarized vortex beams. This research proposes a simple and practical way to control OILS, contributing to our understanding of optical orbit-spin coupling.

On the orbit-induced spin density of tightly focused optical vortex beams: ellipticity and helicity

“…A paraxial linearly polarized optical vortex beam before focusing has essentially zero spin angular momentum density, but in the focal plane after traversing a high NA lens a non-zero spin angular momentum density along the direction of propagation is generated. This property is unique to optical vortex beams, and there have been a number of studies to date on both scalar vortex beams [9,[14][15][16] and vector vortex beams [17][18][19][20][21][22][23][24][25][26][27][28]. The underlying mechanism is a form of spin-orbit interaction (SOI) of light [29], but in contrast to the well-established spinto-OAM conversion it is an orbital to spin angular momentum density conversion.…”