近红外波段硅基金属光子晶体平板的亚波长成像特性

利用时域有限差分方法,理论上研究了由正方形金属嵌入背景材料硅中组成的二维正方晶格和三角晶格光子晶体的亚波长成像特性。采用Drude模型描述金属银的色散特性,在近红外波段该模型可以很好地描述金属的实际介电常数。通过结构参数的设计,在上述两种结构中实现了波长在1550nm附近的亚波长成像,并且发现金属对入射光的吸收使得成像位置处的光强稍有降低,但是对于光子晶体亚波长成像的质量并无影响。相对于通常的硅基空气孔型光子晶体亚波长成像器件,该种硅基金属型全固态光子晶体结构更加稳定,因而可以更好地在复杂全光集成回路中加以实际应用。

Subwavelength Imaging Characteristics of the Near-Infrared Silicon-Based Metallic Photonic Crystal Slabs

The subwavelength imaging properties of the two-dimensional square-lattice and triangular-lattice photonic crystals consisting of square metals immersed in the silicon background are studied by the finite-difference time-domain method. The Drude model is adopted to describe the metal′s dispersion characteristics, which is in a good agreement with the metal′s actual permittivity for the near-infrared wavelengths. Subwavelength imaging for the wavelength around 1550 nm is obtained through designing the parameters of the above two structures. It is found that the influence of metal′s absorption to the incident light can degrade the image spot′s intensity for a little degree, but it is trivial to degrade the subwavelength image′s quality. Compared with the traditional photonic crystal subwavelength-imaging devices consisting of air holes immersed in silicon, this kind of all-solid photonic crystal device consisting of metals immersed in silicon is more stable and can be actually applied in the complex all-optical integrated circuits.