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arXiv physics/0608237physics.optics
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金属薄膜中亚波长圆孔的光透射理论

Theory of Transmission of Light by Sub-wavelength Cylindrical Holes in Metallic Films

N. Garcia, Ming Bai

摘要:

本文对金属薄膜中单个亚波长圆柱孔和亚波长圆柱孔阵列进行了理论分析和时域有限差分法(FDTD)计算。这些计算结果与实验测量结果非常吻合。这种效应必须根据金属的介电常数所表现出的性质来理解,这些金属不能被视为用于光的透射和光的衍射目的的理想金属。我们讨论的情况下,分化良好的金属银和钨。据发现,表面等离子体激元或其他表面波激发的影响,由于周期性的一组孔或其他粗糙度的表面是边际。理论和实验结果表明,这种效应既能增强阵列的透射率,又能抑制阵列的透射率。在实验中观察到的峰结构是由每个孔传输的波前的干涉的结果,并且由独立于材料的表面阵列周期确定。没有通过单个孔的大的透射,就没有通过阵列的大的透射。我们发现,在银的情况下,在所讨论的频率是一种金属,在孔壁有圆柱形等离子体激元,如30年前由Economu等人报道的,增强了传输。但是,正如将要解释的那样,对于表现为电介质的W的情况,当与理想金属波导相比时,也存在大的传输。为了解决这个问题,人们必须使用测量的金属的介电函数。我们对所有这些病例进行了深入的讨论,并与数据进行了比较。

英文摘要:

This paper presents theory and finite-difference time-domain (FDTD) calculations for a single and arrays of sub-wavelength cylindrical holes in metallic films presenting large transmission. These calculations are in excellent agreement with experimental measurements. This effect has to be understood in terms of the properties exhibited by the dielectric constant of metals which cannot be treated as ideal metals for the purpose of transmission and diffraction of light. We discuss the cases of well-differentiated metals silver and tungsten. It is found that the effect of surface plasmons or other surface wave excitations due to a periodical set of holes or other roughness at the surface is marginal. The effect can enhance but also can depress the transmission of the arrays as shown by theory and experiments. The peak structure observed in experiments is a consequence of the interference of the wavefronts transmitted by each hole and is determined by the surface array period independently of the material. Without large transmission through a single hole there is no large transmission through the array. We found that in the case of Ag which at the discussed frequencies is a metal there are cylindrical plasmons at the wall of the hole, as reported by Economu et al 30 years ago, that enhanced the transmission. But it turns out, as will be explained, that for the case of W which behaves as a dielectric, there is also a large transmission when compared with that of an ideal metal waveguide. To deal with this problem one has to use the measured dielectric function of the metals. We discuss thoroughly all these cases and compare with the data.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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