近十幾年來兆赫波科技有著重大的成長，兆赫波在通訊、光譜分析等領域的應用，使得兆赫波光電子學的發展越來越進步。雖然液晶在兆赫波段的應用仍然還在發展中，不過已經有許多團隊利用液晶的雙折射特性與簡單容易的調控方式，在兆赫波段製作出兆赫波段液晶相位調製器，由於銦錫氧化物(ITO)薄膜在兆赫波段的低度透明，所以在電極的選擇相當重要。本論文中，我們首次提出使用矽基板當作電極的兆赫波液晶相位調製器，並利用向列型液晶E7與PI水平配向膜，製作出相位超過2π的相位調製器，與過去文獻相比，每單位伏特所能調控的相位量為72度為最高。我們也發現在低電壓時有蕭特基接觸的現象產生，利用矽基板表面鍍鉻形成歐姆接觸，並使在低電壓與相位移動量呈線性關係。

Terahertz (THz) photonics have been attracted much attention due to its remarkable progress. To date, many phase shifters based on liquid crystals (LCs) in THz region have been reported. Typically, most devices were fabricated using silica substrate coated with ITO as electrode for driving LC molecules. However, the nature of absorption limits its application since ITO material is opaque in the terahertz frequency range. In this thesis, using Si as substrate of LC cell, the electric controlled 2π THz phase shifter was demonstrated. The phase shifter was constructed using nematic LC (E7) that is with thickness of 2.2 mm and sandwiched by two Si substrate. In that case, a maximum of temporal retardation around 1ps can be achieved, revealing that the signal has a phase shift of around 2π at 1THz. The clear voltage-dependence of phase shift of THz radiation indicates that the phase shift can be controlled by altering the applied voltage. This is the first time to our best knowledge that Si can be used to fabricate THz phase shifter without transparent conductive film as electrode. In addition, using thermal evaporating Cr layer to improving contact from Schottky behavior to Ohmic one, phase shift as high as 400 degree was obtained. One should be noted that the phase shifting performance can be accordingly estimated around 72 degree per Volt. This is also the highest phase shifting performance and exhibit the potential of Si substrate for THz photonics.

中文論文審定書 i
英文論文審定書 ii
致謝 iii
摘要 v
Abstract vi
目錄 vii
圖次 ix
表次 xiii
第一章 緒論 1
1.1 前言 1
1.2 論文動機 2
1.3 論文結構 3
第二章 兆赫波時域解析系統理論與液晶介紹 4
2.1 兆赫波在各領域的發展簡介 5
2.2 兆赫波時域解析光譜系統 6
2.2.1 兆赫波產生機制 6
2.2.2 自由空間電光晶體取樣法 8
2.2.3 兆赫波時域解析光譜系統 13
2.3 液晶介紹 16
2.3.1 液晶的分類 16
2.3.2 液晶的物理特性 19
第三章 矽基板作為電極的兆赫波段相位調變器 24
3.1 兆赫波相位調製器 25
3.1.1 磁控兆赫波相位調製器 25
3.1.2 電控兆赫波相位調製器 26
3.2 矽的介紹 30
3.2.1 矽在兆赫波的應用 30
3.2.2 矽在液晶的應用 30
3.3 矽電極兆赫波相位調製器 33
3.4 配向膜對相位調變量的影響 40
3.5 結論 45
第四章 歐姆接觸矽電極兆赫波液晶相位調製器 46
4.1 歐姆接觸與蕭特基接觸的介紹與原理 47
4.2 比較矽基板鍍鉻前後的I-V 曲線 50
4.3 歐姆接觸的矽電極兆赫波相位調製器 52
4.4 結論 55
第五章 總結與未來展望 56
5.1 總結 56
5.2 未來展望 57
參考文獻 59

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