Role of short-range order in manipulating light absorption in disordered media

TL;DR

This study investigates how short-range order in disordered nanostructures influences light absorption, revealing that increased short-range order enhances Bragg scattering and absorption, with stealthy hyperuniform structures outperforming other disordered patterns.

Contribution

It introduces a physical model linking short-range order to light absorption in disordered thin films and demonstrates the superior absorption performance of stealthy hyperuniform structures.

Findings

Higher short-range order enhances Bragg scattering and absorption.

Stealthy hyperuniform structures outperform other disordered patterns.

Optimal absorption occurs at a specific degree of short-range order (around 0.5).

Abstract

Structural correlations have a significant effect on light propagation in disordered media. We numerically investigate the role of short-range order in light absorption in thin films with disordered nanoholes. Two types of disordered distributions, including stealthy hyperuniform (SHU) and hard disk (HD) patterns with different degrees of short-range order, are studied. We find that Bragg scattering induced by short-range order results in the appearance of a gradually sharper absorption peak with the increasing of degrees of short-range order ($\chi$, $\phi$). A physical model is proposed to calculate the in-plane angularly differential scattering cross section $d \sigma^*/d \theta$ of thin-film nanostructures with consideration of {the} structure factor $S(q)$. Results reveal that higher level of short-range order can enhance in-plane Bragg scattering in certain wavelengths and directions corresponding to rich and sharp peaks in {the} structure factor $S(q)$, which can further modify morphology-dependent-like resonances of an individual scatterer {and leads } to {large} improvement of absorptivity in thin films. Besides, the comparison results show that SHU structures exhibit better integrated absorption ($IA$) enhancement than both HD and periodic structures. And there is a transition of local-order phase between hexagonal lattice{s} and square lattice{s for SHU structures}, leading to an optimal absorption performance when $\chi$ is around 0.5 of interest. The present study paves a way in controlling light absorption and scattering using novel disordered nanostructures.