Although it is often assumed that all light-matter interactions at optical frequencies are mediated by electric dipole transitions, strong optical frequency magnetic dipoles do exist. In fact, we see magnetic dipole emission everyday from the Lanthanide ions (such as trivalent Erbium, Europium, and Terbium) that help to illuminate everything from fluorescent lighting to telecom fiber amplifiers. Nevertheless, most applications have overlooked the device implications of these magnetic dipole transitions throughout the visible and near-infrared regime. Moreover, the magnetic dipole contributions of many important transitions have not been fully characterized.

In this talk, we will illustrate how the naturally occurring magnetic dipole transitions of Lanthanide ions provide a new way to probe magnetic light-matter interactions and a new degree of design freedom for active photonic devices.