臺灣博碩士論文加值系統

摘要
在我們的元件設計中，做了三種不同型式接線墊板 (pad) 與光調變器波導之間電信號傳輸線路的比較，第一種是將阻抗值50Ω的微帶傳輸線接於阻抗值24.58Ω的波導中央，第二種是將阻抗值78Ω的微帶傳輸線接於波導中央，第三種是將阻抗值78Ω的微帶傳輸線接於波導兩端。第三種即為行波式光調變器 (Traveling-wave EA modulator) 。由電路模擬計算，將各傳輸線的長度最佳化之後，第三種行波式光調變器有最佳的頻寬~22.4GHz與低的電壓反射係數~40%。行波式光調變器，不但能夠克服RC效應的限制，且能運用長波導來滿足高速操作的需求，同時增加其消光比 (extinction ratio)和光飽和功率(optical saturation power)。
在元件的製程上，我們以高分子材料把脊形波導的兩邊平坦化，將傳輸線的上電極和信號的pad鍍在高分子材料之上。另外，用特殊的斜坡腐蝕法，將接地平板引到與信號的pad相同的高度，以利於使用coplanar microwave probe直接在晶片上進行寬頻的測試。

Abtract
Three different microstrip transmission-line layouts between the pads and an optical modulator waveguide have been designed and compared for their circuit response. In the first design, two 50Ω input and output microstrip transmission lines are connected to the center of the 24.58Ω semiconductor waveguide. In the second design, two 78Ω input and output microstrip transmission lines are connected to the center of waveguide. The third design represents a traveling-wave EA modulator. After optimizing the lengths of the transmission lines through our circuit simulation, we find that the traveling-wave optical modulator (the third layout) have the best circuit response of bandwidth ~22.4GHz and voltage reflection coefficient ~40%. The traveling-wave optical modulator not only overcomes the RC constant limit but also makes use of long waveguide to satisfied the high-speed requirement. At the same time, this circuit increases the extinction ratio and optical saturation power.
In the fabrication process, we use polyimide to planarize both sides of the ridge waveguide and evaporate the top electrode on the polyimide. In addition, we use a special wet etching to form sloped edges for rasing ground pads up to the same level of the signal pad. This will allow us to use coplanar microwave probes to measure the devices.

目錄
第一章緒論…………………………………………………………….1
1-1. 前言………………………………………………………..1
1-2. 元件應用…………………………………………………..1
1-3. 特性優點…………………………………………………..3
1-4. 論文架構…………………………………………………..4
第二章原理…………………………………………………………….5
2-1. 載子躍遷…………………….…………………………...5
2-2. 量子侷限史塔克效應(QCSE)………………...………...6
2-3. 光電流光譜………………..……………………………..8
第三章元件設計與模擬…………………………………………....10
3-1. 簡單RC電路……………………………………………...10
3-2. 傳輸線(Transmission line).………………………….13
3-2-1. 微帶線(Microstrip Line)………………………....14
3-2-2. ABCD 矩陣 (ABCD Matrices)………………........18
3-3. 電路設計與模擬結果…………………………………...23
3-3-1. 50Ω傳輸線…………………………………...…....24
3-3-2. 78Ω傳輸線……………………………………….....27
3-3-3. 行波式電吸收式調變器(Traveling-wave EAM).....28
3-3-4. 模擬結果總結…..……………………...………....30
3-4. 光罩設計與製作…………………………………..…….31
第四章元件製程………………………………………………………33
4-1. 製作流程圖……………………………………………...33
4-2. 製程示意圖……………...………………………………34
4-3. 光調制器之製程步驟與實驗結果………...……………37
第五章量測……………………………………………………………56
第六章 結論……………………………………………………………..59
參考文獻………………….……………………………………………..60

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