含负折射率材料的一维光子晶体的光学传输特性

采用光学传输矩阵方法,模拟研究了由正折射率材料和负折射率材料交替组成的一维光子晶体的光学传输特性.计算了这种含负折射率材料的一维光子晶体的透射谱和色散关系.结果表明,在正入射时,含负折射率材料的光子晶体的带隙要比传统的光子晶体要大得多,并具有狭窄的透射带,从光学薄膜理论的色散关系出发解释了形成上述现象的原因.讨论了在不同的偏振模式下,光以中心波长入射时,反射率随着入射角度的变化关系.发现含负折射率材料的一维光子晶体具有更好的角度特性,可以用来实现对中心波长的全方位反射.

Transmission Properties of One-dimensional Photonic Crystals Containing Negative Refraction Materials

Photonic crystals are artificially fabricated periodic dielectric structures. The periodic dielectric structures exist photonic band gap. The photonic band gap depends on the symmetry of photonic crystals, the refractive index of constituents and the size of unit cell. Conventional photonic crystals are usually constructed by positive refraction materials. In recent years, a complex artificial materials with negative permittivity and negative permeability have attracted much attention theoretically and experimentally. According to the definition, the refractive index is also negative for such materials. In this paper, we consider a new kind of photonic crystals with alternative layers of negative refraction materials and positive refraction materials. Many unique features of light propagation are expected in this structure. By using the condition that the tangential components of electromagnetic field and its first derivative are continuous across the interface, we can get the transfer matrix which connects the fields between the incident end and the exit end. Using the transfer matrix, the transmission coefficient of the monochromatic plane wave can be expressed in terms of its matrix elements. By means of transfer matrix method, the numerical simulation and analyses for the properties of light propagation in one-dimensional photonic crystals with alternative layers of negative refraction materials and positive refraction materials have been made in this paper. The transmittance and dispersion relations of one-dimensional photonic crystals containing negative refraction materials were calculated. It's shown that, on normal incidence, the photonic crystals containing negative refraction materials have wider photonic band gaps which is different from the case of traditional photonic crystals with narrow transmission bands. Based on dispersion relationship, these phenomena were explained. Besides these, the relation between the reflectance and incident angles of different polarization modes when light incident with central wavelength was discussed. It's found that one-dimensional photonic crystals containing negative refraction materials have better angular properties than that of traditional photonic crystals and exhibit an omnidirectional reflection for the incident light with central wavelength.