Band gap of two-dimensional layered cylindrical photonic crystal slab and slow light of W1 waveguide

Hai-Feng Zhang,Zhi-Wei Wang,Ya-Ting Xiang

doi:10.1007/s11082-021-03285-0

Hai-Feng Zhang, Zhi-Wei Wang + Show 1 more

Open Access

https://doi.org/10.1007/s11082-021-03285-0

Copy DOI

Abstract

In this paper, we apply the scatterers of cylindrical rings to a two-dimensional photonic crystals slab. The effects of the number of layers, the thickness, the index, and the height of the cylindrical layers on the photonic band gaps (PBGs) of such slab with different lattice arrangements are studied. It turns out that our new structure helps to obtain a large range of the PBGs. The maximum bandwidth is obtained with the value of 0.117 (2πc/a). The PBGs are moved to the lower frequencies with the augment of thickness, refractive index, and height. The choice of height, refractive index, and thickness is a trade-off, and adding the number of dielectric layers is not always positively correlated with the area of PBGs. In addition, in the W1 waveguide with a triangular lattice layout, we obtain a slow light of 0.026 × c. Compared with the square lattice, the triangular lattice is more suitable for slowing down the speed of light.

Highlights

Photonic crystals (PCs) are a new concept proposed based on the study of the propagating characteristics of light in periodic dielectric materials [1, 2]
Odd symmetry corresponds to odd modes, and even symmetry corresponds to even, and the even and odd modes are the analog of the TM and TE modes, respectively. [11] (In this paper, the even modes are called TM-like modes, the odd modes are called TE-like modes, and the definition of TE mode and TM mode will be mentioned later.)
The plane-wave expansion (PWE) method is used to study the effects of different structural parameters on the different modes of the 2D-PCS, and compare the traits of the photonic band gaps (PBGs) in the triangular and square lattices

Summary

Introduction

Photonic crystals (PCs) are a new concept proposed based on the study of the propagating characteristics of light in periodic dielectric materials [1, 2]. Their work laid the foundation for subsequent research, which was carried out one after another [18,19,20] This kind of 1D-PCs has not been investigated of the two-dimensional case, so it is necessary to study the PBGs features of the 2D-PCS with the scatterers of cylindrical rings. The composition of the scatterer is GaAs. The PWE method is used to study the effects of different structural parameters on the different modes of the 2D-PCS, and compare the traits of the PBGs in the triangular and square lattices. After introducing the line defect, the group velocity of 0.026×c in the triangular lattice is obtained

Band structure theory

Slow light theory

The influences of N on the band structures of the square and triangular cases

Group velocity discussion of introducing line defects

Conclusion