Optical properties of spherulite opals

TL;DR

This paper investigates how the birefringence of spherulite-based opals influences their optical band structure, revealing new pseudogaps and enhanced reflectivity without altering symmetry.

Contribution

It demonstrates that spherulitic birefringence significantly affects dispersion and creates pseudogaps in opal band structures, a novel insight into their optical properties.

Findings

Spherulitic birefringence does not change opal symmetry.

Birefringence leads to new pseudogaps in the band structure.

Enhanced reflectivity observed due to birefringence effects.

Abstract

Spherulites are birefringent sturctures with spherical symmetry, which are typically observed in crystallized polymers. We compute the band structure of opals made of close-packed assemblies of highly birefringent spherulites. We demonstrate that spherulitic birefringence of constituent spheres does not affect the symmetries of an opal, and yet significantly affects the dispersion of eigenmodes, leading to new pseudogaps in sections of the band structure, and consequently enhanced reflectivity.