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博碩士論文 etd-0704107-181718 詳細資訊
Title page for etd-0704107-181718
論文名稱
Title
漸變形錐型波導之輻射現象分析
Radiation of Adiabatic Tapered Waveguides
系所名稱
Department
畢業學年期
Year, semester
語文別
Language
學位類別
Degree
頁數
Number of pages
91
研究生
Author
指導教授
Advisor
召集委員
Convenor
口試委員
Advisory Committee
口試日期
Date of Exam
2007-06-26
繳交日期
Date of Submission
2007-07-04
關鍵字
Keywords
輻射、錐型波導
tapered waveguide, radiation
統計
Statistics
本論文已被瀏覽 5657 次,被下載 1127
The thesis/dissertation has been browsed 5657 times, has been downloaded 1127 times.
中文摘要
錐型波導(tapered waveguide)通常被使用在光斑轉換器(spot-size converter)及功率分配器(power divider)上。一般來說,這些元件的輻射現象是很難用光束傳播法(beam propagation method, BPM) 和時域有限差分法(finite-difference, time-domain, FD-TD)來分析。我們應用全特微模態展開方法(full eigenmode expansion technique, FEMET)研究漸變形(adiabatic)介電質錐型波導的傳播情形。
漸變型介電質錐型波導通常被認為無反射及輻射情況之元件,輸入波導的導波模態會逐步地轉換成相對應的輸出波導的導波模態,為一對一(one to one) 的模態演化(mode evolution),且無模態轉換(mode conversion)的情形發生。然而,當輸出波導不支援相對應的入射導波模態(incident guiding mode)時,則此導波模態可能會激發出其他更高階的導波模態而造成模態轉換或激發出高階輻射模態而產生輻射現象。有趣的是我們將探討模態轉換與輻射現象情形,並且利用數值實驗來觀察此現象。
另外針對全特徵模態展開方法特性,我們使用傾斜直線波導(tilted straight waveguide)結構來當做分析範例,利用座標轉換的方式求出傾斜直線波導精確場型分佈,與數值模擬結果比較,以驗證全特徵模態展開的精確性。
Abstract
Tapered waveguides are often used as spot-size converters and power dividers. In general, radiation in these devices is hard to analyze by either BPM or FD-TD methods. We apply the full eigenmode expansion technique (FEMET) to study the propagation of an adiabatic dielectric tapered waveguide.
We often assume that wave propagation in an ideal “adiabatic” dielectric waveguide suffer no reflection nor radiation loss. It is especially true for the fundamental mode propagation in an “adiabatic” dielectric waveguide. Thus, the fundamental mode of the input waveguides will be converted to the corresponding fundamental mode of the output waveguide whenever the two are connected by an adiabatically tapered waveguide. However, the higher-order modes do not always propagate through the tapered waveguide when the output waveguide does not support that particular guiding mode. It is interesting to predict such radiation phenomena and to observe them in a numerical experiment.
In this thesis we consider the titled straight waveguide (TSR) as our test example. Since TSR has an exact solution in its natural coordinate system, we can study computational characteristics of FEMET via TSR examples. Using FEMET and FD-FD method, we carefully examine mode evolution, conversion radiation and reflection of many quasi-adiabatic tapered waveguides. Finally the apparent visual radiation angles are defined and computed as function of taper angle core/cladding indices and incident mode order for both TE and TM mode cases.
目次 Table of Contents
第一章 導論 1
1. 1 簡介.............................................................................1
第二章 FEMET理論分析錐形波導 4
2. 1 FEMET理論基本觀念...............................................4
2. 2 TE與TM極化入射FEMET理論架構與推導...........6
第三章 FEMET理論分析傾斜直線波導 12
3. 1 傾斜直線波導介紹...................................................12
3. 2 傾斜直線波導理論...................................................14
3. 3 數值模擬結果與討論...............................................19
第四章 漸變形錐型波導分析 36
4. 1 漸變形錐型波導定義...................................................36
4. 2 漸變形錐型波導分析介紹...........................................37
4. 3 TE基模入射漸變形錐型波導分析.............................39
4. 4 漸變形錐型波導輻射機制...........................................49
4. 5 輻射模擬結果與討論...................................................52
4. 6 FEMET與FDFD之分析結果比較.............................71
第五章 結論與未來工作 79
參考文獻 80
中英對照表 81
參考文獻 References
[1] 黎聯群, “多模干涉器的場理論及元件物理,” 碩士論文, 國立中山大學光電工程研究所(2006).

[2] Yasuhide Tsuji, Masanori Koshiba, and Tomohide Tanabe, "A Wide-angle Beam Propagation Method Based on a Finite Element Scheme, " IEEE Transactions on magnetics .vol. 33, no. 2, pp. 1544~1547 (1997).

[3] Junji Yamauchi, "Propagating Beam Analysis of Optical Waveguides," Hosei University, Tokyo, Japan(2003).

[4] T. L. Wu and H. W. Chang, “Guiding mode expansion of a TE and TM transverse-mode integral equation for dielectric slab waveguides with an abrupt termination,” J. Opt. Soc. Am. A 18, 2823–2832 (2001).

[5] A. Ishimaru, "Electromagnetic Wave Propagation, Radiation and Scattering", p. 104-105 Englewood Cliffs, N.J. Prentice-Hall, (1991).

[6] Y.-S. Chou, “Multi-Mode Propagation Method for Bi-directional Ring Cavities”, master thesis,National Sun Yat-sen University, Kaohsiung(2003).
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