Angular-momentum biasing: A new paradigm for linear, magnetic-free, non-reciprocal devices

A paradigm to obtain magnetic-free, linear non-reciprocal devices is presented based on biasing with the angular-momentum vector, achieved either by directly spinning a loading material or by imparting spatiotemporal modulation over a substrate. This technique is shown to be applicable to any range of the electromagnetic spectrum, and even to different types of waves, such as acoustic waves. Furthermore, it can be realized with integration-friendly materials, such as metals and semiconductors, thus opening a path for the much sought realization of integrated, compact and linear non-reciprocal components.