论文总字数：11391字

摘 要

通常的光栅，无论是透射型还是反射型光栅都具有如下特点：零级衍射光强最强，但不能色散；一级衍射虽然能色散，但光强很弱。本文研究梯型超表面的三明治结构金属块阵列的反射谱。我们实验观察到超周期的金属纳米孔超周期阵列的等离激元共振模式在横向磁场极化激发下的分裂。并且观察到在零阶传输与第一阶透射的分裂模式。然而，分裂模式现象在一级传播比零阶传播更加明显。它显示了分裂模式是由于亚波长周期金属孔阵列的等离激元共振的模式和共振超周期金属光栅的模式在表面之间的耦合。

我们设计了一种非对称三明治金属块阵列系统，系统的上层结构为非对称的两块金属片。其表面是一种具有横向亚波长的微细结构的超表面。其单胞在一个方向上为亚波长的，而在与这个方向垂直的方向上是超波长的。其衍射光具有如下特点：零级衍射和一个一级衍射被强烈抑制，光强非常弱；而另一个一级衍射光强却非常强，衍射效率在测量的波长范围内超过50%；这一反常衍射现象预计可以应用到分光计中作为光的色散器件。

关键词：反常衍射；梯型超表面；超波长；亚波长

Abstract

The usual grating, both transmission type and reflection type grating have the following characteristics: the zero order diffraction intensity is the strongest, but not the dispersion; although the first order diffraction can dispersion, but the light intensity is very weak. In this paper, we study the reflection spectrum of the sandwich structure metal block array.We experimentally observed surface plasmon resonance mode splitting in a super-period metal nanohole array grating under the transverse magnetic polarization excitation. The mode splitting was observed in the zeroth order transmission and also in the first order transmission. However, the mode splitting phenomenon is more evident in the first order transmission than in the zeroth order transmission. It is explained that the mode splitting is due to the coupling between the surface plasmon resonance mode in the subwavelength period metal nanohole arrays and the resonance mode of the super-period metal grating.

We design an asymmetric sandwich metal block array system, the upper structure of the system is two pieces of non symmetrical metal sheet. The surface is a super surface with micro structure with lateral sub wavelength. The single cell is a sub wavelength in one direction, and in the direction perpendicular to the direction it is a super wavelength. The diffraction light has the following characteristics: zero order diffraction and a first-order diffraction was strongly inhibited, the light intensity is very weak; and another first-order diffraction light intensity is very strong, diffraction efficiency in the measurement of the wavelength range of more than 50%; the anomalous diffraction phenomenon is expected can be applied to the spectrometer as a light dispersion devices.

Key Words: Anomalous diffraction; ladder type super surface; super wavelength; sub wavelength

目 录

摘要…………………………………………………………………………………II

ABSTRACT………………………………………………………………………Ⅲ

第一章 绪论………………………………………………………………………1

第二章 CST软件的使用及模型设计…………………………………………4

第三章 非对称三明治金属块阵列的衍射谱和电流分布……………13

结论…………………………………………………………………………………19

参考文献…………………………………………………………………………20

1. 绪论

我们知道，作为信息的载体，光子优于电子；然而在集成上，光子元件却输于电子元件。这是由于光所具有的衍射效应，使得介电光学元件的尺寸受到了极大的限制（至少为波长的一半）。因此，研究和利用亚波长结构的超表面的反常衍射从而控制电磁波的传播具有重要的意义。

1998年第一次报道了金属薄膜的纳米孔阵列中的增强光透射。过去十年，这一现象已被广泛地研究。增强光透射发生在亚波长周期性金属纳米孔阵列的频率被匹配到表面等离激元共振的频率时。表面等离激元共振的周期性传输纳米增强光透射纳米孔结构的金属薄膜。

自从1998年，T. W. Ebbesen等人在金属膜上打上周期性的亚波长的小孔阵列，发现了光异常增强透射现象[1,2]。此后，亚波长、深度亚波长结构（微结构的尺寸小于甚至远小于工作波长）就受到极大地关注。但超波长结构却从此被忽略。另一方面，对于由一维或二维纳米孔或纳米粒子阵列组成的亚波长表面等离激元光栅结构，其衍射具有如下特点：零级衍射通常是传播模式而高级衍射通常是消逝波且是近场波。

请支付后下载全文，论文总字数：11391字