Artificial Magnetism and Topological Phenomena in Optics

Recent years have witnessed intense research activities to effectively control the flow of photons using various classes of optical structures such as photonic crystals and metamaterials. In this regard, optics has benefited from concepts in condensed matter and solid-state physics, where similar problems concerning electronic wavefunctions arise. An important example of such correspondence is associated with the photon dynamics under the effect of an artificial magnetic field. This is especially important since photons, as neutral bosons, do not inherently interact with magnetic fields. One way to mitigate this issue is to exploit magneto-optical materials. However, as is well known, using such materials comes with several issues in terms of optical losses and fabrication challenges. Therefore, clearly of interest would be to devise certain schemes, which employ conventional dielectric materials, and yet provide an artificial magnetic field e.g. through geometric phases imprinted in the photonic wave amplitudes. Here, we utilize such schemes to observe various optical wave phenomena arising from the associated artificial magnetism. First, we show that light propagation dynamics in a twisted multicore optical fiber is governed by the Schrödinger equation in the presence of a magnetic potential. Using this, we experimentally observe Aharonov-Bohm suppression of optical tunneling in these structures. Moreover, we use notions from topological insulators to demonstrate the first dielectric-based topological lasers both in 1- and 2-dimensional lattices of microring resonators. Our measurements show that such laser arrays exhibit significant improvement in terms of robustness against defects and disorder, as well as higher slope efficiencies as compared to conventional laser arrays. Finally, we show both theoretically and experimentally, that the cooperative interplay among vectorial electromagnetic modes in coupled metallic nanolasers can be utilized as a means to emulate the classical XY Hamiltonian. In particular, we discern two phases in these systems, akin to those associated with ferromagnetic (FM) and antiferromagnetic (AF) materials