Direct interferometric measurement of non-reciprocity induced by a plasmonic metasurface with false chirality

TL;DR

This paper demonstrates a direct interferometric method to measure non-reciprocity caused by false chirality in plasmonic metasurfaces, revealing opposite phase shifts for surface plasmons in different directions.

Contribution

It introduces a novel interferometric setup using a customized Sagnac interferometer to detect non-reciprocal phase differences in plasmonic structures with high sensitivity.

Findings

Non-reciprocal phase shifts observed in surface plasmon propagation

High sensitivity interferometric detection method developed

Potential applications in sensing and signal processing

Abstract

Nonreciprocity is an important scientific concept related to the broken symmetry of light propagation through a system in 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 non-reciprocity. 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 set-up. The main advantages of our proposed system are high sensitivity to non-reciprocal 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 non-reciprocity and its detection in numerous physical and chemical processes suggests a wide range of practical applications as well as deeper scientific insights.