用超材料表面結構設計與合成人造馬克斯威爾魚眼透鏡

Abstract

本篇論文主要是研究表面等離子極化激元(surface plasmon polariton)在週期性結構上的傳遞現象。週期性結構是由許多單位晶元按照固定週期來擺放成一維、二維或三維的結構。我們利用商用電磁模擬軟體CST來模擬週期結構的色散圖(dispersion diagram)與反向位圖(reflection phase)來決定表面電漿極激子激發所在的操作頻率，並且模擬出波形傳遞現象。另外研究的主要目的是希望能夠聚焦表面等離子極化激元能量，而我們選定的形狀是環形的形狀，所以需要藉由改變每一個單位晶元上的形狀大小來達到波形轉換方向與聚焦，我們需要藉由折射率的變化來達成波形變換方向。在超材料的領域中有三個人造透鏡可實現，這次的論文中所以我們運用週期性結構來合成出人造馬克斯威爾魚眼透鏡。對於馬克斯威爾魚眼透鏡，半圓的透鏡能使波從圓形波變成平面波而完整圓能使能量點對點的聚焦。為了要得知透鏡能力的好壞，我們需要制定出一些參數來說明，如功率輸出效率、功率衰減率。

In this thesis, we mainly research the surface plasmons polariton (SPP) propagating phenomena on the periodic structure surface. The periodic structure is composed of many unit cells with a fixed period that are arranged in one-dimensional, two-dimensional or three-dimensional fashions. We use the commercial electromagnetic simulation software CST to simulate the periodic structure of the dispersion diagram and reflection phase to determine the operating frequency of the surface plasmon polariton excitation, and to simulate the wave propagating phenomena. Another of the main objective is to focus surface plasmon polariton energy, which is done by judiciously setting the shapes of the rings. We need to change the size of each unit cell to achieve wave bending and focusing achieved by changing the refractive index. In using metamaterials, there are three common types of artificial lens that can be designed and synthesized. In this paper, we use the periodic structure to synthesize the artificial Maxwell fisheye lens. Half of the lens is to make the spherical wave emanating from the source located at the edge of the lens into a plane wave and the other half of the lens makes the energy converge to a point on the other side of the source, thereby realizing the Maxwell fisheye lens. In order to know the quality of the lens, we need to determine some parameters to clarify, such as power output efficiency, and power decay rate.