Orbital angular momentum induced beam shifts

TL;DR

This paper experimentally investigates how orbital angular momentum (OAM) affects beam shifts during optical reflection, revealing that OAM increases both spatial and angular shifts and couples them, with implications for optical metrology.

Contribution

It provides the first detailed experimental analysis of OAM-induced beam shifts and confirms theoretical predictions, expanding understanding of OAM's role in optical phenomena.

Findings

Beam shifts increase with OAM index up to 3.

OAM couples spatial and angular beam shifts.

Experimental results agree with theoretical models.

Abstract

We present experiments on Orbital Angular Momentum (OAM) induced beam shifts in optical reflection. Specifically, we observe the spatial Goos-H\"anchen shift in which the beam is displaced parallel to the plane of incidence and the angular Imbert-Fedorov shift which is a transverse angular deviation from the geometric optics prediction. Experimental results agree well with our theoretical predictions. Both beam shifts increase with the OAM of the beam; we have measured these for OAM indices up to 3. Moreover, the OAM couples these two shifts. Our results are significant for optical metrology since optical beams with OAM have been extensively used in both fundamental and applied research.