Bloch bound states in the radiation continuum in a periodic array of dielectric rods

TL;DR

This paper demonstrates the existence of three types of Bloch bound states in the continuum in a periodic array of dielectric rods, revealing their properties, conditions for existence, and how they manifest in scattering behavior.

Contribution

The study introduces an approach based on Hankel function expansion to identify and analyze different types of Bloch BSCs in dielectric rod arrays, including their conditions and properties.

Findings

Three types of Bloch BSCs identified in dielectric rod arrays.

Second type supports power flux along the array.

BSCs can be detected via scattering function analysis.

Abstract

We consider an infinite periodic array of dielectric rods in vacuum with the aim to demonstrate three types of a Bloch bound states in the continuum (BSC), symmetry protected with a zero Bloch vector, embedded into one diffraction channel with nonzero Bloch vector, and embedded into two and three diffraction channels. The first and second types of the BSC exist in a wide range of material parameters of the rods, while the third occurs only at a specific value of the radius of the rods. We show that the second type supports the power flux along the array. In order to find BSC we put forward an approach based on the expansion over the Hankel functions. We show how the BSC reveals itself in the scattering function when the singular BSC point is approached along a specific path in the parametric space.