Tunability of photonic band gaps in one- and two-dimensional photonic crystals based on ZnS particles embedded in TiO2 matrix

Amel Labbani,Abdelmadjid Benghalia

doi:10.1007/s13320-012-0052-9

Abstract

Using the Maxwell-Garnett theory, the evolution of the refractive index of titanium dioxide (TiO2) doped with zinc sulfide (ZnS) particles is presented. The presence of the nano-objects in the host matrix allows us to obtain a new composite material with tunable optical properties. We find that the filling factor of ZnS nanoparticles greatly alters photonic band gaps (PBGs). We have calculated also the photonic band structure for electromagnetic waves propagating in a structure consisting of ZnS rods covered with the air shell layer in 2D hexagonal and square lattices by the finite difference time domain (FDTD) method. The rods are embedded in the TiO2 background medium with a high dielectric constant. Such photonic lattices present complete photonic band gaps (CPBGs). Our results show that the existence of the air shell layer leads to larger complete photonic gaps. We believe that the present results are significant to increase the possibilities for experimentalists to realize a sizeable and larger CPBG.

Highlights

Photonic crystals (PCs) [1, 2] are artificial materials with a periodically modulated dielectric permittivity
We have calculated the photonic band structure for electromagnetic waves propagating in a structure consisting of zinc sulfide (ZnS) rods covered with the air shell layer in 2D hexagonal and square lattices by the finite difference time domain (FDTD) method
We have investigated the influence of the volume fraction occupied by ZnS nanoparticles in the TiO2 matrix on photonic band gaps (PBGs). 2D core-shell photonic crystals, square and hexagonal lattices for which the effect of the thickness of the shell layer exists between the ZnS rods and the background on the complete photonic band gaps (CPBGs) are studied in this paper

Summary

Introduction

Photonic crystals (PCs) [1, 2] are artificial materials with a periodically modulated dielectric permittivity. To describe the optical properties of the new composite material (ZnS grains in the TiO2 matrix) with different filling factors ƒ, we use the Maxwell-Garnett (MG) theory [13]. (b) Fig. 2 Modification of the (a) real part and (b) imaginary part of the composite optical index ñ of the TiO2 matrix doped with ZnS particles. We denote the gap by En (respectively Hn ) occurring between the n-th and the (n+1)-th bands of E (respectively H) polarization

Hexagonal lattice

Square lattice

Conclusions