Quasi-flat bands in waveguide arrays

TL;DR

This paper investigates the spectrum of electromagnetic waves in a one-dimensional waveguide array with positive and negative refraction index waveguides, revealing the presence of quasi-flat bands in the linear mode spectrum.

Contribution

It introduces a novel waveguide array model with mixed refraction indices and analyzes its linear mode spectrum, highlighting the emergence of quasi-flat bands.

Findings

Identification of quasi-flat bands in the spectrum

Waveguide array acts as a one-dimensional photon crystal

Potential implications for controlling light propagation

Abstract

Coupled electromagnetic waves propagating in a waveguide array are discussed. This waveguide array can be considered as one dimensional photon crystal composed from the unit cell containing three different waveguides, namely, two positive refraction index waveguides and one waveguide with negative refraction index. Spectrum of the linear modes of electromagnetic waves in this device contains the quasi-flat band.