Foam as a self-assembling amorphous photonic band gap material

TL;DR

This paper demonstrates that disordered 2D foams can serve as self-assembled templates for isotropic photonic band gap materials, with potential applications in scalable and cost-effective photonic devices.

Contribution

It introduces the use of slightly polydisperse disordered 2D foams as templates for isotropic PBG materials, highlighting the importance of foam structure and refractive index contrast.

Findings

Dry foam structures with threefold nodes maximize PBG.

Transition to wet foam closes the PBG due to defect modes.

Optimal foam area fraction enhances PBG in experiments.

Abstract

We show that slightly polydisperse disordered 2D foams can be used as a self-assembled template for isotropic photonic band gap (PBG) materials for transverse electric (TE) polarization. Calculations based on in-house experimental and simulated foam structures demonstrate that, at sufficient refractive index contrast, a dry foam organization with threefold nodes and long slender Plateau borders is especially advantageous to open a large PBG. A transition from dry to wet foam structure rapidly closes the PBG mainly by formation of bigger fourfold nodes, filling the PBG with defect modes. By tuning the foam area fraction, we find an optimal quantity of dielectric material, which maximizes the PBG in experimental systems. The obtained results have a potential to be extended to 3D foams to produce a next generation of self-assembled disordered PBG materials, enabling fabrication of cheap and scalable photonic devices.