How orbital angular momentum affects beam shifts in optical reflection

TL;DR

This paper investigates how adding orbital angular momentum to a light beam influences the four types of beam shifts upon reflection, revealing a coupling described by a 4x4 matrix through theoretical and experimental analysis.

Contribution

It introduces a coupling matrix that describes how orbital angular momentum affects the four beam shifts during optical reflection, combining theory and experiments.

Findings

Orbital angular momentum couples the four beam shifts.

The coupling is represented by a 4x4 matrix.

Experimental results confirm the theoretical predictions.

Abstract

It is well known that reflection of a Gaussian light beam ($\text{TEM}_{00}$) by a planar dielectric interface leads to four beam shifts when compared to the geometrical-optics prediction. These are the spatial Goos-H\"{a}nchen (GH) shift, the angular GH shift, the spatial Imbert-Fedorov (IF) shift and the angular IF shift. We report here, theoretically and experimentally, that endowing the beam with Orbital Angular Momentum (OAM) leads to coupling of these four shifts; this is described by a $4 \times 4$ mixing matrix.