Study on transmission characteristics in photonic crystals with negative effective index of refraction

Abstract

Transmission spectra from equivalent negative refractive photonic crystals (PCs) composed of a triangular array of air cylinders in a GaAs matrix are studied by finite-difference time-domain method in the paper. Mechanism of wave resonance is probed and propagation of optical waves in the PCs is described in terms of effective refraction index and Bloch waves. Our numerical results show that probability of spontaneous radiation would be enhanced extremely under the influence of Bloch resonance waves, stimulated emission and photon tunnel effect, resulting in the optical waves localized greatly in the PCs at particular frequencies. In addition, we find out that the position of transmission peaks, with values far greater than unit, can be controlled by tuning the central frequency of waveguide source. It means that photon current in the PCs also can be controlled to optimize transmission properties of PCs, so as to meet the requirements of novel optical devices based on PCs.

Investigation of a patch antenna based on I-shaped left-handed material

“…Bloch wave and surface wave's resonance would be produced for the electromagnetic wave's Bragg dispersion at a frequency. We have studied resonance effect in triangle structure whose effective refraction coefficient is −1 [15], thus, we calculated the S parameters (S11 and S21) of the medium used for the photonic crystal patch antenna, then the medium's effective permittivity and permeability were extracted by the method of NRW [8]. The calculated result in Fig.…”