一維介電質-金屬光子晶體方向感測濾波性質之研究

Abstract

光子晶體(PCs)是由不同折射率的介質，按照週期性排列而成的結構且具有空間週期性特性的光學介質，它的固有特性是存在著一些光子能隙(PBGs) 或稱「光子頻率禁帶」，當頻率落在禁帶中的光或電磁波是無法在光子晶體結構中傳播的。本論文目的是在設計含有缺陷模態之介電質-金屬光子晶體濾波器並研究及分析其特性。在此篇論文中，共研究了兩個主題，藉由轉移矩陣法（TMM）模擬計算吸收率及透射率對應波長之關係圖。 第一個主題是研究一維介電質-金屬光子晶體，在缺陷模態中對於電磁波的影響。利用介電質-金屬材料的堆疊，中間夾帶缺陷層的三明治結構所產生單向不可逆的特性，我們研究堆疊週期數的改變及入射方向改變時對波長吸收所造成的影響。另外，我們也分析了在TE和TM不同模態下改變入射角度時的現象。 第二個主題是利用介電質-金屬材料的堆疊來提升入射波的透射。我們通過在結構的頂端和底部添加抗反射層的處理，使得透射率更為提升。另外，我們也分析了在TE和TM不同模態下改變入射角度時的現象。Photonic crystals (PCs), artificially periodic structures, are known to have the photonic bandgaps (PBGs), in which electromagnetic waves cannot propagate through the PCs. In this thesis, we use the transfer matrix method (TMM) to study the wave properties for the metal-dielectric PCs. The first topic is to study the one-way (unidirectional) transmission properties in a one-dimensional dielectric-metal PC containing a defect layer. By calculating the absorptance we find the considered structure can exhibit the unidirectional transmission. This unidirectional property is further investigated by changing the angle of incidence for TE and TM modes. The second theme is to study how to enhance the transmission in a dielectric-metal PC. It is found that by adding the antiflection layer at the bottom or top of the PC, significant enhancement in the transmission can be obtained in our structure. In addition, the phenomenon of enhancement is also studied as a function of the angle of incidence for both TE and TM modes.