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

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.

Keywords

Photonic crystals / photonic band gap / nanoparticles / ZnS / TiO₂

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