絕緣體上鍍矽(SOI)波導因為結構本身的高折射率對比造成較強的光場侷限特性，因此能夠有效地縮小光電元件尺寸，並應用於高密度的積體光路。然而，SOI波導本身存在強烈的極化相依特性，會嚴重降低光通訊系統的表現。為了解決極化相依特性對積體光路帶來的影響，過去提出了許多極化旋轉器與極化偏振器的相關研究，然而大部分的設計需要較長的元件尺寸才能得到較好的效率，使積體光路難以達到微型化的目的。
在本研究中，我們利用L形混合式電漿波導設計微型的模態耦合型極化旋轉器，藉由破壞波導結構的對稱性，以加大兩傾斜模態的模態等效折射率差，因此可以使極化旋轉器在極短的長度內達到高的極化旋轉效率。我們利用三維有限元素法(3D-FEM)來分析我們所設計的極化旋轉器，並優化元件結構設計，可以在元件長度為2.25 μm時，得到TE極化光轉TM極化光之極化旋轉效率99.4%以及插入損耗為2.6 dB。
同時，我們也利用雙層混合式電漿波導設計了TM極化偏振器，透過極化相依的特性，使TE極化光以反射及洩漏模態的方式消散，但TM極化光則會耦合成混合型的表面電漿波模態而能繼續在極化偏振器中傳播。透過3D-FEM優化元件結構，我們可以在元件長度為1 μm時，得到TM極化偏振器的極化消光比為17.2 dB以及插入損耗1.92 dB。本論文成功地利用混合式電漿波導設計了超微型的極化旋轉器與極化偏振器，相較於一般極化旋轉器與極化偏振器，我們所提出的元件長度更短，更能有助於積體光路的微型化。

Silicon on insulator (SOI) structures is proven to be a very promising technology for developing high-density photonic integrated circuits (PICs). Due to the high index contract and low loss, SOI structures can reduce the device size. However, SOI devices possess strong polarization dependence, which may degrade the performance of optical communication systems. To overcome this drawback, various types of SOI-based polarization rotators and polarizers have been proposed with long device lengths.
We first propose an ultracompact polarization rotator based on an L-shaped asymmetric hybrid plasmonic waveguide. The simulation is carried out by a three-dimensional finite element method (3D-FEM, COMSOL Multiphysics) to optimize the device performance. Due to the plasmonic effect and asymmetric L-shaped waveguide, two hybrid modes with enlarged modal index difference are induced to shorten the device length. We can realize an ultrashort rotator length of 2.35μm with the polarization conversion efficiency is 99.4% and the insertion loss is 2.6 dB。
We have also proposed an ultracompact TM polarizer based on a double hybrid plasmonic waveguide which only supports TM mode between two silicon dielectric waveguides. Meanwhile, the TE mode is cutoff on the TM polarizer. The simulation is also carried out by the 3D-FEM to analyze the polarizer properties and optimize the polarizer. The optimized design shows that, as the device length is 1 µm, we can obtain the extinction ratio and insertion loss are 17.2 dB and 1.92 dB, respectively.
We successfully utilize the hybrid plasmonic waveguide to design ultrashort polarization rotator and polarizer. The device length of our proposed polarization rotator and polarizer are very short compared to the conventional silicon-based polarization devices, which can help to realize high-density PICs.

誌謝 i
中文摘要 ii
Abstract iii
目錄 v
圖目錄 vi
第一章 緒論 1
1.1 Silicon on insulator 光波導 1
1.2 極化分集系統與極化偏振器 2
1.3 極化旋轉器 4
1.4 混合式表面電漿波元件 8
1.5 研究動機 13
第二章 表面電漿波 14
2.1 表面電漿共振模態 14
2.2 表面電漿波之激發方法 23
第三章 以L形混合式電漿波導設計極化旋轉器 27
3.1 非對稱結構極化轉換器 27
3.2 L形混合式電漿波導極化旋轉器之數值分析 31
3.3 製程容忍度 42
第四章 以雙層混合式電漿波導設計TM極化偏振器 49
4.1 混合式電漿波導極化偏振器 49
4.2 雙層混合式電漿波導TM極化偏振器之數值分析 51
第五章 結論 62
參考文獻 63

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