Total Internal Reflection of Orbital Angular Momentum Beams

TL;DR

This paper explores how beams with orbital angular momentum behave under total internal reflection, revealing that geometric shifts are independent of OAM, while OAM spectrum changes depend on the input mode and focusing, supported by experiments and theory.

Contribution

It provides new insights into the behavior of OAM beams during total internal reflection, linking beam shifts and spectrum modifications through experimental and theoretical analysis.

Findings

Beam shifts are independent of OAM and focusing.

OAM spectrum changes depend on input mode and focusing.

Theoretical relationship between beam shifts and spectrum changes established.

Abstract

We investigate how beams with orbital angular momentum (OAM) behave under total internal reflection. This is studied in two complementary experiments: In the first experiment, we study geometric shifts of OAM beams upon total internal reflection (Goos-H\"anchen and Imbert-Fedorov shifts, for each the spatial and angular variant), and in the second experiment we determine changes in the OAM mode spectrum of a beam, again upon total internal reflection. As a result we find that in the first case, the shifts are independent of OAM and beam focussing, while in the second case, modifications in the OAM spectrum occur which depend on the input OAM mode as well as on the beam focussing. This is investigated by experiment and theory. We also show how the two methods, beam shifts on the one hand, and OAM spectrum changes on the other, are related theoretically.