Spontaneous generation and active manipulation of real-space optical vortex

• Main Authors: Kim, Dongha, Baucour, Arthur, Choi, Yun-Seok, Shin, Jonghwa, Seo, Min-Kyo
• Format: Journal Article
• Language: English
• Published: 04-02-2022
• Subjects: Physics - Mesoscale and Nanoscale Physics; Physics - Optics
• DOI: 10.48550/arxiv.2202.02335

Optical vortices host the orbital nature of photons, which offers an extra
degree of freedom in photonic applications. Unlike vortices in other physical
entities, optical vortices require structural singularities, which restrict
their abilities in terms of dynamic and interactive characteristics. In this
study, we present the spontaneous generation and external magnetic
field-induced manipulation of an optical vortex and antivortex. A
gradient-thickness optical cavity (GTOC) consisting of an Al/SiO2/Ni/SiO2
multilayer structure realised the distinct transition between the trivial and
non-trivial topological phases, depending on the magneto-optic effects of the
Ni layer. In the non-trivial topological phase, the mathematical singularities
generating the optical vortex and antivortex pair in the reflected light
existed in the generalised parameter space of the thicknesses of the top and
bottom SiO2 layers, which is bijective to the real space of the GTOC. Coupled
with the magnetisation, the optical vortex and antivortex in the GTOC
experienced an effective spin-orbit interaction and showed topology-dependent
dynamics under external magnetic fields. We expect that field-induced
engineering of optical vortices will pave the way for the study of topological
photonic interactions and their applications.