準週期排列奈米結構形成類超薄平面光學透鏡

Abstract

在本論文中，我們對於準週期性納米孔陣列，聚焦以及成像能力進行了一系列的理論探討和論證。而利用準週期性排列設計納米孔所製作出來的光學二元掩模，可以用作類似於超薄平面光學透鏡的功能，不僅能夠在遠離表面數十波長的位置產生亞波長的能量熱點，也可以使多個點光源組成的複雜結構成像。 首先，當一個單色平面波入射到準週期性納米孔陣列時，我們可以發現在不同波段皆可以產生亞波長的聚焦點。此外，在一些特殊的成像距離，甚至能在中間區域產生類似甜甜圈圖案的強度分佈。這種現象提供了另一種可以達成STED系統的新方案，並且應用在納米光刻技術和光學成像之中。 再來，通過分析兩個可調的點光源，我們可以有效的訂定平面光學透鏡的數值孔徑與有效成像區域，這樣的結果跟現象相似於具有高N.A.的常規光學透鏡。另外，通過準週期性納米孔陣列的透鏡，可以在現有的光學透鏡不容易應用的情況下使用，例如X射線成像和納米光學電路的應用。

In this thesis, the focusing and imaging abilities of a quasi-periodic nanohole array in a metal screen have been theoretically investigated and demonstrated. Such an optical binary mask with nanoholes designed in an aperiodic arrangement can function as an ultrathin flat optical lens, not only focusing the sub-wavelength energy hot-spot but also imaging complex structures composed of multiple light sources at tens of wavelengths away from the lens surface. First, the focusing ability has been demonstrated when a monochromatic plane wave normally incident into a quasi-periodic nanohole array. Moreover, at some special imaged distance, the intensity distribution even produced doughnut-like shape patterns in middle area. Such phenomena give another new scheme to achieve STED system which can be employed in nanolithography and optical imaging applications. Second, via resolving two adjacent testing objects at different separations, the effective numerical aperture (N.A.) and the effective imaging area of the planar optical lens can be evaluated, mimicking the imaging function of a conventional lens with high N.A. Furthermore, by using the quasi-periodic nanohole array as an ultra-thin planar optical lens, important applications such as X-ray imaging and nano-optical circuits may be found in circumstances where conventional optical lenses cannot readily be applied.