Control of optical spin Hall shift in phase-discontinuity metasurface by weak value measurement post-selection

TL;DR

This paper demonstrates control over the optical spin Hall shift using phase-discontinuity metasurfaces and weak value measurement post-selection, enabling tunable precision in nanoscale photonic applications.

Contribution

It introduces a method to control OSH shift via phase-retardance post-selection on PMS, advancing optical spin manipulation techniques.

Findings

OSH shift depends on incidence and refraction angles at PMS.

Weak value measurement with variable phase controls the OSH shift.

Potential for enhanced nanoscale photonic sensing and angular momentum transfer.

Abstract

Optical spin Hall (OSH) shift has been observed by weak measurement amplification in a refraction beam passing through air-glass interface, the refractive index gradient $\vec{\nabla} n$ being normal to the interface. Phase-discontinuity metasurface (PMS) possesses $\vec{\nabla} n$ tangential to the metasurface, and depending on the incidence angle either positive or negative refraction takes place satisfying the generalized Snell's law. Rapid phase-change over subwavelength distance at PMS leads to a large $\vec{\nabla} n$, enabling a direct observation of OSH shift. Here, we identify that the relative OSH shift between optical beams with spins $\pm 1$ depends on incidence and refraction angles at PMS, and construct a measurement of OSH effect with a variable phase retardance in the post-selection to demonstrate a control of transverse shift. and demonstrate a control of OSH shift by constructing a weak value measurement with a variable phase retardance in the post-selection. Capability of OSH shift control permits a tunable precision metrology applicable to nanoscale photonics such as angular momentum transfer and sensing.