Nonreciprocity in millimeter wave devices using a magnetic grating metamaterial

The control and manipulation of many of light's fundamental properties, such as reflectivity, has become a topic of increasing interest since the advent of engineered electromagnetic structures—now known as metamaterials. Many of these metamaterial structures are based on the properties of dielectric materials. Magnetic materials, on the other hand, have long been known to interact with electromagnetic waves in unusual ways; in particular, their nonreciprocal properties have enabled rapid advances in millimeter wave technology. Here, we show how a structured magnetic grating can be employed to engineer electromagnetic response at frequencies upwards of hundreds of gigahertz. In particular, we investigate how nonreciprocal reflection can be induced and controlled in this spectral region through the composition of the magnetic grating. Moreover, we find that both surface and guided polaritons contribute to high-frequency nonreciprocity; the nature of these is also investigated. Control of electromagnetic radiation at high frequencies is a current challenge of communications technology where our magnetic gradient might be employed in devices including signal processing filters and unidirectional isolators