Negative refraction in 1D photonic crystals

Negative refraction has been the subject of considerable interest and it may provide the possibility of a variety of novel applications. It occurs in Meta-materials which have simultaneous negative permittivity εε and permeability μμ, where in-homogeneities are much smaller than the wavelength of the incoming radiation. Recently, it has been shown that photonic crystals (PCs) may also exhibit negative refraction, although they have a periodically modulated positive permittivity εε and permeability μμ. We have theoretically studied the negative refraction in one-dimensional (1D) photonic crystals (PCs) consisting of dielectric ZnSe with air. By using transfer matrix method and Bloch theorem, we have studied the photonic band structure and group velocity, and with the help of group velocity, we have obtained the frequency bands of negative refraction. We found that negative refraction may occur near the low frequency edge of the second and fourth bandgaps.