Light guiding by artificial gauge fields

Abstract

Artificial gauge fields enable uncharged particles to behave as if affected by external fields. Generated by geometry or modulation, artificial gauge fields are instrumental in realizing topological physics in photonics, cold atoms and acoustics. Here, we experimentally demonstrate waveguiding by artificial gauge fields. We construct artificial gauge fields by using waveguide arrays with non-trivial trajectories. Tilting the arrays results in gauge fields that are different in the core and cladding, shifting their dispersion curves, thereby confining the light to the core. In a more advanced setting, we demonstrate waveguiding in a medium with the same gauge and dispersion everywhere, where the only difference between the core and the cladding is a phase shift in the dynamics of the gauge fields, which facilitates waveguiding via bound states in the continuum. Waveguiding and bound states in the continuum via artificial gauge fields relate to a plethora of systems, ranging from photonics and microwaves to cold atoms and acoustics. Optical guiding by a synthetic gauge field is experimentally demonstrated through an array of evanescently coupled identical waveguides, opening the door to applications of artificial gauge fields in optical, microwave and acoustic systems and in cold atoms.