零折射曲面超透镜理论及金属亚波长结构的单透性

The image with one-sixth illuminating wavelength has been realized by metal superlens in experiment, which deals with the key manufacturing technique of CMOS chip. Further more the magnified and reduced images have been observed by using the curved superlens. However we found that the metal superlens is quite different from perfect lens made of the double negative (DNG) material in principle. In DNG perfect lens, the image is focused by the negative refraction, but in metal superlens the image is formed by the imprint effect caused by the zero-refraction. We have proposed the theory for plane metal superlens and obtained the theoretical results which coincide with the experimental results well. But the theory for the curved superlens is lacked，this is just our first content to establish the theory; The zero-refraction caused by negative permeability (ENG) in metal film was found theoretically by us, in many aspects, which is different from the phenomena caused by Epsilon-Near-Zero (ENZ). So the ENG zero-refraction should be investigated in detail, especially the differences between the ENG and ENZ zero-refractions. These will be the second content; The optical one-way transmission device should play the key role in optical circuit just as the diode in electric circuit. We theoretically and experimentally found one-way transmissions in metal subwavelength structures, which are assisted by the unique properties of the surface plasma polaritons (SPP). The mechanism is entirely different from that have been proposed or realized before. We will realize the more ideal one-way structures in theory and experiment. The one-way structure involves two kinds, which are the linear type and the two-dimensional plane type. These will be the third and fourth contents respectively. The above contents are all proposed based on the research results of our former NFNS project.

金属超透镜已在实验上实现了六分之一波长的光刻线宽，这涉及芯片制作的核心技术。特别是近期实验上还实现了曲面超透镜的放大和缩小功能。但我们发现其工作原理并不同于双负薄膜的两次聚焦成像，而是零折射的印象成像。我们用零折射理论计算的平面超透镜成像结果与实验符合很好，但是曲面超透镜理论还有待建立，这是研究内容之一。金属膜零折射也是我们新发现的，它在很多方面不同于零介电常（ENZ）造成的零折射现象。我们将对其理论作进一步细致研究，特别是它与ENZ零折射的不同之处，这是内容之二。光学单透器件相当于电子线路中的二极管，其重要性为大家公认。我们发现金属亚波长结构也可以产生单透现象，这是由于金属表面等离子体的特性造成，这与当前人们采用的所有单透原理都不同。我们将从实验和理论两个方面实现更理想的单透结构。具体分为二维平面型和线型单透结构，这是内容之三和四。以上内容全部是我们前一个项目成果基础上面临的新问题。

获得了平面超透镜在典型超透镜装置中最佳成像满足的两个条件；（1）对称条件，金属膜两边介电常数相等；（2）在对称条件下，要求介质介电常数与金属介电常数实部之和等于1；获得了弯曲超透镜成像的基本特性和必须遵守的基本要求：（1）理论上发现掩膜板上刻痕位移与成像位移成线性关系，这说明弯曲超透镜可以保证成像结构不失真；（2）保证图像可分辨必须遵守一个线距与线宽的二次函数关系。这为超透镜设计以及掩膜板设计提供了一个保证成像质量的理论依据。以上成果符合零折射理论，从理论上加深了人们对超透镜成像机制的认识。理论上共提出了7种单透结构并获得成功，包括面型和线性两种，它们主要特点是利用金属表面等离子体作为能量载体。这些成果为将来的实验工作和实际应用提供了思路。同时每一种结构都是对于光学互易原理的巧妙应用。我们把互易原理在单透结构中的表现归结为通道效应，通过这些工作将通道效应清楚地展示出来，为加深人们理解互易原理和单透的关系提供了具体实例。