應用於微波通訊之一維光子晶體的穿透光譜

Abstract

本論文提出可應用於傳統及未來微波通訊（E-band）之一維光子晶體波段選擇器設計及光電特性模擬。一維光子晶體是由高低不同折射率的兩種材料依照週期性排列而來，此設計可抑制某特定頻段範圍的光穿透度，其中材料的選取，採用了一般常作為透明基板的鈉鈣玻璃，及具有電場或磁場可調控性的常用液晶BDH-E7。在設計上，為了研究液晶軸向轉動對本論文中一維光子晶體特性的影響，因此根據Fréedericksz transition及牛頓法來更準確地模擬液晶在外加電場作用下的行為；除此之外，選擇適當的玻璃及液晶缺陷層厚度、數目及在結構中的位置，使其具有不同的光譜特性，並觀察液晶層於電場下之行為對一維光子晶體的影響。本論文研究一維光子晶體穿透光譜的頻段為30至120 GHz，此範圍涵蓋了目前大多微波與毫米波通訊的使用頻段。在應用上，本論文提出應用於不同頻帶技術之可電控單一頻段選擇器、電磁帶通濾波器，及電磁干擾保護罩。

This study is concerned with the transmissive properties of several electrically tunable one-dimensional photonic crystals (PCs) for applications in multigigabit millimeter-wave communications, especially in E-band (70–90 GHz) wireless technology. Each PC multilayer is sequentially composed of two dielectric materials with high and low refractive indices. And this design can inhibit light transmittance in some specific frequency range. From many references, we know that the characteristics of liquid crystal change with electric field and magnetic field. In order to more accurately research the properties of one-dimensional photonic crystal by the rotation effect of liquid crystal, we adopt Freedericksz transition and Newton method to simulate the behavior of liquid crystal in electric field. By kinds of defect layers compositions, we research the optical properties of these hybrid structures. By specific designs, we can get four kinds of electrically tunable frequency selectors, and a kind of bandpass filter.