Observation of a Photonic Orbital Gauge Field

Abstract

Gauge field is widely studied in natural and artificial materials. With an effective magnetic field for uncharged particles, many intriguing phenomena have been observed in several systems like photonic Floquet topological insulator. However, previous researches about the gauge field mostly focus on limited dimensions such as the Dirac spinor in graphene materials. Here, we firstly propose and experimentally observe an orbital gauge field based on photonic triangular lattices. Disclination defects with Frank angle created on such lattices breaks the original lattice symmetry and generates purely geometric gauge field operating on orbital basis functions. Interestingly, it is found that bound states near zero energy with the orbital angular momentum are intensively confined at the disclination as gradually expanding . Moreover, the introduction of a vector potential field breaks the time‐reversal symmetry of the orbital gauge field, experimentally manifested by the chiral transmission of light on helical waveguides. The orbital gauge field further suggests fantastic applications of manipulating the vortex light in photonic integrated devices.This article is protected by copyright. All rights reserved