Measuring circular phase-dichroism of chiral metasurface

Abstract

The ability of chiral media to differentiate circularly polarized light is conventionally characterized by circular dichroism (CD) which is based on the difference in the absorption of the incident light for different polarizations. Thus, CD probes the bulk properties of chiral media. Here, we introduce a new approach termed as circular phase-dichroism that is based on the surface properties and is defined as the difference of the reflection phase for different circularly polarized incident lights in characterizing chiral media. As a demonstration, we measure the reflection phase from planar chiral sawtooth metasurface for circularly polarized light in the visible range using a simple Fabry Perot interference technique. The measured circular phase-dichroism is also crosschecked by conventional CD measurement of the transmitted light and by full-wave simulations. Our results demonstrate the potential applications of circular phase-dichroism in sensing and metasurface characterizations.