基于散射矩阵方法的金属光子晶体薄膜异常光学透射研究

Study on Extraordinary Optical Transmission through Arrays of Holes Metal Films Based on Scattering Matrix Method

散射矩阵方法是一种基于频域的研究方法。将散射矩阵方法用于亚波长周期性金属小孔结构的透射特性研究。以金属铜薄板为研究对象,薄板刻蚀方格子光子晶体空气圆孔;用洛伦兹-德鲁德(Lorentz-Drude)模型来表征铜的介电常数ε;对不同的薄板厚度、周期大小和空气孔孔径的结构进行透射谱分析。并与时域有限差分方法计算所得结果相对照,二者吻合较好。仿真结果表明,如果在金属薄板上刻蚀亚波长周期性空气孔,原本不能透射光波的金属薄板将会出现异常透射现象。这是由周期性金属小孔中表面等离子波子共振导致的结果。用散射矩阵方法与时域有限差分方法分别基于频域和时域进行仿真,二者相互验证,从而可以有效地检验结果的正确性,进而减少以实验来验证时域有限有限差分仿真结果的成本,增强仿真能力。

Scattering matrix method is a research method in frequency domain.Transmission spectra of metal films with periodic air holes is studied based on this method.Copper slabs etched with periodic square lattice of air holes are used.Lorentz-Drude model is used to describe permittivity ε of copper.Transmission spectra are obtained for different thicknesses of copper slabs,different lattice constants and different radii of air holes.The results agree well with the results obtained by finite-difference time-domain method（FDTD）.It is shown that while light cannot be transmitted thought metal slabs,extraordinary optical transmissions can be observed if metal slabs are drilled with periodic air holes.This is mainly caused by surface plasmon resonance in the metal photonic crystal slabs.Results can be verified by comparing them obtained from the scattering matrix method in frequency domain and the FDTD method in time domain.Thus it can reduce the cost to verify the results experimentally and enhance the ability of simulation.