穿透式單一波長超穎透鏡

Abstract

超穎透鏡具有體積小且幾乎感受不到重量的優點。在傳統光學元件中，若需要達到消色差或是其他光學用途，必須透過多個鏡組來實現。這不僅會增加重量，而且現在的光學透鏡都是玻璃組成，非常易碎。穿透式超穎透鏡是由次波長結構來組成，穿透率接近100％，且具有2π的相位補償。其中可以藉由PB Phase的概念來達到2π的相位補償。 本論文的超穎透鏡是選用氮化鎵來當作介電質矩形結構的材料。利用電感耦合式電漿乾蝕刻來蝕刻氮化鎵的深度達600奈米。在乾蝕刻過程中，遇到了嚴重影響光學行為的針狀效應。本論文將深入探討針狀效應的生成原因以及解決方法。 最後以雙面拋光的藍寶作為基板，且以氮化鎵作為介電質矩形結構之材料，製作而成的穿透式超穎透鏡分為兩種：正向聚焦以及斜向聚焦。兩者的穿透效率分別高達91%以及71%。

Metalens have advantages of light and small. There are many disadvantages of traditional optical components such as bulky and fragile if ones want to get the purpose of achromatization. Transparent metalens are made of subwavelength structures. They perform nearly 100% in transmittance, and are capable of offering 2π phase compensation. 2π phase compensation can be achieved by PB phase. In the thesis, we chose GaN as the material of rods, using ICP-RIE to etch 600nm depth of GaN. During the process of etching GaN, we found needle effect which seriously affect optical behavior. We will discuss what reasons caused needle effect, and offer solutions to it. Last but not least, we chose double-polished sapphire as substrate, and GaN as rods to fabricate our transparent metalens. There are two different kinds of transparent metalens in the thesis, normal focusing and oblique focusing. The transmittance of two metalens are 91% and 71% respectively.