Direct Interferometric Measurement of Nonreciprocity Induced by a Plasmonic Metasurface with False Chirality

Nonreciprocity is an important scientific concept related to the broken symmetry of through a system in the forward and reverse directions. This effect lies in the origin of various applications including signal processing, noise reduction, unidirectional propagation, and sensing. Here, we show that propagation of Surface Plasmons (SP) within a structure having a false chirality exhibits a nonreciprocity. The SP waves propagating in opposite directions within the structure acquire opposite Pancharatnam-Berry (PB) phases. To detect this phase difference, we introduce a novel interferometric technique based on a customized Sagnac setup. The main advantages of our proposed system are high sensitivity to nonreciprocal phase changes, high precision incidence angle alignment, and the inspection of the k-space enabled by sufficiently wide range of incidence angles. We believe that a pivotal role of the nonreciprocity and its detection in numerous physical and chemical processes suggests a wide range of practical applications as well as deeper scientific insights.