Hyperuniform Disorder in Photonic Crystal Slabs with Intrinsic non-Hermiticity

TL;DR

This paper investigates how hyperuniform disorder affects light propagation in photonic crystal slabs considering intrinsic non-Hermiticity due to loss, providing a theoretical framework and numerical validation for scattering behavior.

Contribution

It introduces a theoretical model for disorder scattering in non-Hermitian photonic bands with complex effective mass, extending understanding beyond idealized lossless systems.

Findings

Scattering loss in non-Hermitian bands follows a modified power law with a finite constant term.

Theoretical predictions match tight-binding and FDTD simulations with realistic parameters.

Non-Hermitian effects alter the scattering behavior compared to Hermitian cases.

Abstract

Hyperuniform disorder is a type of correlated disorder characterized by vanishing spectral density at small wavevectors, making the configuration effectively homogeneous on long length scales. In photonics, hyperuniform disorder is promising for generating isotropic photonic pseudogaps and engineering photonic crystal waveguides. However, these studies are largely restricted to idealized lossless settings, although all photonic systems necessarily have loss. In this work, light propagation in photonic crystal slabs with imposed hyperuniform disorder is investigated theoretically and numerically. The system is intrinsically non-Hermitian due to radiative loss, with non-Hermiticity appearing as a complex effective mass of a quadratic photonic band. A theoretical framework for disorder scattering is analytically derived in Hermitian and non-Hermitian quadratic bands with real and complex effective mass, respectively. In contrast to the power law behavior $|\mathbf{k}|^\alpha$ observed in the Hermitian case (where $\alpha$ is the hyperuniformity exponent), the scattering loss in the non-Hermitian band is given by $C_0+C_{\beta_2}\cdot|\mathbf{k}|^{\beta_2}$, where $C_0$ is a finite constant and the exponent $\beta_2\leq 2$. Our theoretical predictions are verified with tight-binding and Finite-Difference Time-Domain simulations with realistic photonic crystal parameters, based on recent experiments.