Wave scattering phenomena in time-varying metamaterials: Analysis of switched close and open electromagnetic systems and their design

Thanks to the recent advancements in metamaterial technology, the real-time control of the macroscopic artificial material parameters has become faster and faster, transforming the reconfigurable metamaterials into a new class, named temporal metamaterials, that have shown promising applications in dynamic wave manipulation well-beyond the conventional artificial media. Among the different modulation schemes that can be applied, this thesis focuses on the step-like modulation scheme for its capability to realize a temporal interfaces, an unusual light matter interaction where the electromagnetic field perceives an instantaneous change of the material properties and reacts to this by generating a scattered field at a different frequency with respect to the original one. In particular, this thesis investigates the so-called boundary induced temporal interfaces that offer the same anomalous scattering response, but without changing the material's intrinsic properties. Both closed and open electromagnetic systems capable to trigger boundary-induce temporal interfaces are studied in this thesis, introducing the corresponding analytical models, defining the proper design guidelines and, finally, validating the proposed devices via numerical full-wave simulations. This thesis demonstrates that boundary-induced temporal interfaces represent a technology-ready solution for conceiving devices based on temporal metamaterials, due to their compatibility with metasurface technology.