Causality relations for materials with strong artificial optical chirality

TL;DR

This paper derives generalized causality-based relations for chiral optical materials, enabling verification of experimental data and analysis of material resonances and anomalies.

Contribution

It introduces generalized Kramers-Kronig relations including Blaschke terms for strongly chiral artificial materials, linking causality to optical observables.

Findings

Relations help verify experimental data accuracy.

They allow locating material resonances and anomalies.

Quantify chiral splitting in optical responses.

Abstract

We demonstrate that the fundamental causality principle being applied to strongly chiral artificial materials yields the generalized Kramers-Kronig relations for the observables -- circular dichroism and optical activity. The relations include the Blaschke terms determined by material-specific features - the zeros of transmission amplitude on the complex frequency plane. By the example of subwavelength arrays of chiral holes in silver films we show that the causality relations can be used not only for a precise verification of experimental data but also for resolving the positions of material anomalies and resonances and quantifying the degree of their chiral splitting.