Narrowband and ultranarrowband filters with electro-optic structurally chiral materials

TL;DR

This paper explores how electro-optic structurally chiral materials can be engineered to create narrowband and ultranarrowband optical filters, with tunable properties influenced by electric fields and material thickness.

Contribution

It introduces a novel approach to designing tunable narrowband and ultranarrowband optical filters using electro-optic structurally chiral materials with specific symmetry and defect structures.

Findings

The filters' bandwidths can be controlled by the slab thickness and electric field magnitude.

Electro-optic effects enable significant reduction in device thickness.

The design allows for selective reflection or transmission based on polarization.

Abstract

When a circularly polarized plane wave is normally incident on a slab of a structurally chiral material with local $\bar{4}2m$ point group symmetry and a central twist defect, the slab can function as either a narrowband reflection hole filter for co-handed plane waves or an ultranarrowband transmission hole filter for cross-handed plane waves, depending on its thickness and the magnitude of the applied dc electric field. Exploitation of the Pockels effect significantly reduces the thickness of the slab.