Steering far-field spin-dependent splitting of light by inhomogeneous anisotropic media

TL;DR

This paper demonstrates how inhomogeneous anisotropic media, specifically q plates, can be used to control spin-dependent light splitting in the far-field, with tunable patterns for potential applications in nano-optics and quantum information.

Contribution

It introduces a method to steer spin-dependent light splitting using structured anisotropic media, exemplified by the q plate, with tunable splitting patterns and angles.

Findings

K-space SDS occurs before real-space SDS in the far-field.

Splitting pattern shows multilobe and rotatable symmetry.

Lobe number and rotation angle are tunable by structure and polarization.

Abstract

An inhomogeneous anisotropic medium with specific structure geometry can apply the tunable spin-dependent geometrical phase to the light passing through the medium, and thus can be used to steer the spin-dependent splitting (SDS) of light. In this paper, we exemplify this inference by the q plate, an inhomogeneous anisotropic medium. It is demonstrated that when a linearly polarized light beam normally passes through a q plate, k-space SDS first occurs, and then the real-space SDS in the far-field focal plane of a converging lens is distinguishable. Interestingly, the SDS, described by the normalized Stokes parameter S3 shows a multilobe and rotatable splitting pattern with rotational symmetry. Further, by tailoring the structure geometry of the q plate and/or the incident polarization angle of light, the lobe number and the rotation angle both are tunable. Our result suggests that the q plate can serve as a potential device for manipulating the photon spin states and enable applications such as in nano-optics and quantum information.