Optical response of a bilayer crystal

TL;DR

This paper extends classical optical response theory from single-layer to bilayer crystals, accounting for interlayer interactions and multiple reflections, enabling better comparison with experimental data.

Contribution

It introduces a generalized susceptibility for bilayer crystals and details the calculation of local and macroscopic fields, advancing theoretical modeling.

Findings

Derived a new expression for bilayer susceptibility

Demonstrated the impact of interlayer interactions on optical response

Provided a framework for direct comparison with experiments

Abstract

We extend the recently developed classical theory for the optical response of a single-layer crystal to bilayers. We account for the interaction between the two atomic planes and the multiple reflections inside the crystals. We show how to define a global susceptibility meaningful for the bilayer crystal and how its expression varies compared to the single-layer case. We compute both the local and the macroscopic fields which allow us for a direct comparison with experimental data.