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

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 (χ, φ). A physical model is proposed to calculate the in-plane angularly differential scattering cross section dσ * /dθ 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 (I A) enhancement than both HD and periodic structures. And there is a transition of local-order phase between hexagonal lattices and square lattices for SHU structures, leading to an optimal absorption performance when χ is around 0.5 of interest. The present study paves a way in controlling light absorption and scattering using novel disordered nanostructures.

Analysis of dependent scattering mechanism in hard-sphere Yukawa random media

“…One important factor that leads to the dependent scattering mechanism is known as the structural correlations, which describe possible reminiscence of order (usually short-or medium-ranged) existing in the spatial variation of the dielectric constant in disordered media 31 . They can lead to definite phase differences among the scattered waves 11,[31][32][33][34][35][36] , and hence result in remarkable impacts on the transport and scattering properties of light. The most well-known type of structural correlations is the hard-sphere positional correlation in disordered media consisting of pure hard spheres without any additional inter-particle interactions 34,37 .…”

Effective transport properties of conformal Voronoi-bounded columns via recurrent boundary element expansions

“…Even so, there have been some useful early approaches to this problem including levelcut random fields 3 and random Voronoi tessellations 4,5 . Recently there has been a resurgence in interest in hyper-uniform disordered (HUD) structures 6 that have ordering intermediate between crystals and random glasses, offering a number of useful properties such as enhanced isotropy 7 , distributed absorption 8 and wide bandgaps with dense bands 9 . Centroidal Voronoi tessellations (CVT) 10 are an important example of this class of geometry 11 , and are a plausible model of some real structures such as anodic alumina pores 12 .…”

Structural correlations and dependent scattering mechanism on the radiative properties of random media

“…Studying the radiative properties of micro/nanoscale disordered media is not only of great fundamental importance in understanding the light-matter interaction physics, like Anderson localization [1][2][3][4] and anomalous transport behaviors of radiation (or light) [5][6][7][8], but also has profound implications in applications such as random lasers [9,10], solar energy harvesting and conversion [11][12][13][14], radiative cooling [15,16] and structural color generation [17], etc. In such media, radiation is scattered and absorbed in a very complicated way, which is usually described by the radiative transfer equation (RTE) in the mesoscopic scale.…”