Effect of dielectric permittivity variation in the transmission spectra of non-compact 2D-arrays of dielectric spheres

Abstract

Transmission spectra of two dimensional photonic crystals made of arrays of dielectric spheres are affected by the sphere dielectric permittivity. In this paper we present a systematic study of this influence for different compactness of the lattices. The transmission spectra were simulated by finite-different time-domain method. The system studied is a plane of spheres of dielectric permittivity e (ranging from 2 to 9) arranged in triangular symmetry with varying compactness. Compactness is characterized as the ratio (R) of the sphere diameter (Φ) over the lattice period (Λ) and is considered from R = 1, close packed samples, to R = 0, 2. The transmission spectra of these samples are calculated for normal incident radiation of wavelengths in the interval extending from 0.8 to 5 times the sphere diameter. The sphere arrays present a number of resonant modes that appear as dips in the transmission spectra. The frequency position of the resonances is discussed in relation to those of the Mie modes of the is...