Numerical investigation of the possibility of negative refraction in a slab-shaped photonic crystal

It has been claimed that a negative refraction index could be measured in a slab-shaped two-dimensional photonic crystal, which is constructed of a square array of dielectric rods. In our numerical experiments, a Gaussian pulse is applied to analyze the negative refraction, and a dipole source is used to check superlensing effect. Based on our results, the observation of the negative angle of refraction is due to the spread of the electromagnetic field, and the flow of the wave shows no evidence of negative refraction. Furthermore, if a dipole source propagates into the photonic crystal, a dipole image should be found on the other side of the crystal, because of the superlensing effect; unfortunately, the image never appeared in our simulations. In conclusion, a two-dimensional photonic crystal may not be treated as a left-handed material.