摘要
本論文中，我們提出一種新幾何結構波導的行波式電致吸收光調變器(Traveling-Wave Electroabsorption Modulator，TWEAM)。為了要獲得元件高速操作，以得到良好的微波傳遞特性，降低在波導的寄生電容是必要的。在本工作中，一種叫做兩次底切蝕刻的製程是被發展，為了降低在波導的寄生電容。
在論文一開始，首先用BPM的軟體去計算這新結構二維的光模態形式，確定像這種形狀的波導確實有侷限光模態的能力。接著基於等效電路的模型，不同波導結構的微波特性是被研究，用來決定所要製作的底切蝕刻結構，模擬的結果用來說明新幾何結構可以提供我們製作出特性更好的電致吸收光調變器。
藉由選擇性蝕刻溶液的配方，底切蝕刻的製程方式是被使用，以降低在波導的寄生電容。而H3PO4 :HCl的配方被使用去蝕刻在多量子井(MQW)層上的P-InP層；H3PO4:H2O2:H2O的配方被使用去蝕刻在多量子井(MQW)層，以決定出波導核心的寬度。
底切蝕刻的製程已成功的被發展，元件經過量測的結果：其元件的電對電響應(E-E Response)在40GHz頻率時，其S11為-17.5 dB、而S21為-2.7dB在40GHz的電傳輸，如此顯示因連續二次的底切蝕刻所造成的低寄生電容，確實可以改善元件的頻帶寬。

Abstract
In this thesis, we propose a new geometrical structure of waveguide for the application of traveling-wave electroabsorption modulator (TWEAM). As approaching to high-speed performance in TWEAM, low parasitic capacitance in the waveguide is necessary to get good microwave propagation properties. In this work, a novel processing called two-step undercut-etching the active region (UEAR) is developed to reduce the parasitic capacitance.
First of all, Beam Propagation Method (BPM) is used to calculate this 2-D structure optical modes ensuring the guiding capability in such kind of waveguides. Based on an equivalent circuit model, the microwave propagation on different structures of waveguide is then investigated to decide the UEAR waveguide structure.
By the selectively etching solution on InP/InGaAsP, the processing by two-step UEAR is developed to reduce the parasitic capacitance in the waveguide core. H3PO4:HCl is used to selectively etch P-InP layer on the top of InGaAsP M.Q.W. (multiple quantum wells, active region). H3PO4:H2O2:H2O is subsequently and selectively remove InGaAsP M.Q.W.s to define the waveguide core.
This processing has been successfully developed. The electrical transmission measurement on this kind of TWEAM shows low reflection S11 of < -17.5dB and a low insertion loss S21 of < –2.7dB from D.C. to 40GHz, indicating high microwave performance on such two-step UEAR waveguide can be achieved due to the low parasitic capacitance.

目錄

目錄……………………………………………………………………….….ii
誌謝…………………………………………………………………………..iv
中文摘要……………………………………………………………………...v
英文摘要……………………………………………………………………..vi

第一章 緒論.………………………………………………………………… 1
1.1 前言 1 1.2 研究動機 1
1.3 論文架構 2

第二章 電致吸收光調變器之工作原理……………………………………..3
2.1 Franz-Keldysh effect的描述 3
2.2量子侷限史塔克效應 (Quantum Confined Stark Effect) 4
2.3電子、電洞波函數的影響 7

第三章 光波導和行波式電極模擬分析………..……………………………9
3.1光波導的模擬分析 9
3.1.1 材料結構和特性 9
3.1.2 光波導的模擬結果 12
3.2 行波式電極模擬分 13
3.2.1 行波式電極 13
3.2.2 微波模擬分析 14
3.3 總結 16

第四章 元件製作………….…….………………………………..……….….18
4.1 元件製作步驟 18
4.2 製程討論.…………………………………………………...……….. 36

第五章 量測結果………………………..………………………………..… 41
5.1 電對電微波傳輸特性 42
5.2 光對光傳輸特性 44

第六章 結論…………………………………………………………………..45

參考文獻……..……………………………………………………….. ……..46

附錄一……..……………………………………………………….. ……..48

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