電致光吸收調變器由於其高效率、低頻擾以及容易與其他半導體元件整合等因素而在高速光纖通訊上倍受關注。為了改善一般塊狀波導結構電容電阻對高速的限制影響所以使用了行波式波導作為微波傳遞的結構。於本論文中用一般的行波式電致光吸收調變器作為研究的對象。
論文分為兩個主題，第一部分為比較縮腰式結構與單純脊狀結構光波導的行波式電致光吸收調變器。利用DC-40GHz的小訊號以及10Gb/s的數位訊號傳輸作為兩種結構的比較。一般單純的脊狀結構在光穿透量方面相較於縮腰式波導約小於3dB，將此作一計算在微波低頻上將相差6dB之多。於一般的脊狀結構加上50Ω作為阻抗匹配量測小訊傳輸頻寬可以獲得淤15GHz，而縮腰是波導在相同量測條件之下可以獲得25GHz的小訊號頻寬。數位傳輸實驗方面縮腰式波導相較於一般脊狀波導在10-9的偵測點接收敏感度高出3.2dB，且縮腰是波導擁有-36.2dB的高靈敏度。
第二個主要部分是電致光吸收調變器作為波長轉換器的應用。利用Cross-Absorption Modulation以及光電流的產生作用為基礎，將可以使電致光吸收調變器達到波長轉換的功能。使用較長的行波式電致光吸收調變器有利於產生較高的消光比。於實驗結果得到轉換效率部分目前估計約有-26dB，轉換高低比率大於20dB。

Electroabsorption modulators (EAM) have attract a lot of interests in high-speed optical communication due to low chirp, high-efficiency operation and the capability to be integrated with other semiconductor devices. Enhancing the operation by overcoming the trade-off between RC-limitation and high-speed performance, traveling-wave types of EAMs (TWEAM) have been documented to be a good candidate. In this thesis, a novel type of TWEAMs, namely undercut-etching-the-active-region type (UEAR), have been characterized and analyzed.
There are two topics in this thesis, namely (1) one is to compare the performance of the UEAR and conventional ridge-waveguide (RW) types of TWEAM. The regime of D.C. to 40GHz small-signal modulation and 10 Gbits/sec large-signal data transmission are used to characterize and compare the performance of TWEAMs. In comparison with conventional ridge-waveguide (RW) TWEAM, 3dB lower optical-insertion-loss, at least 6dB higher in RF-link (D.C. to 40GHz) and faster electro-optical response (3dB bandwidth of 25GHz at 50Ω-termination for UEAW and 15GHz for RW) are obtained in UEAW-TWEAM. Error-free 10Gbits/sec operation with high sensitivity of –36.2 dBm and low swing voltage of 0.6V have been achieved in UEAW-TWEAM, a 3.2dB enhancement over RW-TWEAM, indicating the trade-off in designing electroabsorption modulators can be greatly released by novel type structure (UEAW).
(2) The other topic is the application of TWEAM to all-optical wavelength converters. The generating photocurrent by optical absorption is the effect accompanying with the electrical-to-optical modulation in the EAM. Using the properties of cross-absorption and generating photocurrent, high-speed all-optical modulation can be potentially implemented in the application of EAMs. Long -waveguide high-speed TWEAMs can thus have high-extinction ratio performance in all-optical conversion. The conversion efficiency of -26dB and high extinction ration of >20dB are obtained in this experiment, showing the potential in the application of all-optical conversion.

第一章 諸論 01

第二章 原理

第一單元 電致光吸收調變器吸收原理 05
第二單元 微波模型原理 07
第三單元 波長轉換器的工作原理 18
第四單元 小訊號頻擾參數原理 20
第五單元 Cr-YAG 光傳播計算 24

第三章 實驗與結果討論

第一單元 電致光吸收調變器三大參數量測 26
第二單元 脊狀波導與縮腰式波導之比較 33
第三單元 波長轉換器 40
第四單元 小訊號頻擾參數量測 44

第四章 結論 53

附錄 A. 微波公式 55
附錄 B. 圖表列表 58
附錄 C. 使用儀器 61
參考資料與文獻 62

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