Bound states in the continuum in periodic structures with structural disorder

TL;DR

This paper investigates how structural disorder affects the transition from bound states in the continuum to quasi-BICs in periodic photonic structures, highlighting differences in robustness and implications for practical applications.

Contribution

It provides a detailed analysis of the robustness of symmetry-protected and accidental BICs against disorder, revealing how disorder-induced localization impacts Q factors.

Findings

Symmetry-protected BICs are more robust against disorder than accidental BICs.

Structural disorder induces mode localization, reducing the effective system length and Q factor.

Results inform the design of photonic structures with BICs in real-world, disordered environments.

Abstract

We study the effect of structural disorder on the transition from the bound states in the continuum (BICs) to quasi-BICs by the example of the periodic photonic structure composed of two layers of parallel dielectric rods. We uncover the specificity in the robustness of the symmetry-protected and accidental BICs against various types of structural disorder. We analyze how the spatial mode localization induced by the structural disorder results in an effective reduction of the system length and limits the Q factor of quasi-BICs. Our results are essential for the practical implementation of BICs especially in natural and self-assembled photonic structures, where the structural disorder plays a crucial role.