摘要

在本論文中，主要目的為利用弗列斯涅的折射原理(Fresnel Refraction)來設計並製作大角度偏折的埋藏式高分子複合波導。我們使用在矽晶片成長的二氧化矽為披覆層(cladding)，高分子材料為波導元件的導光層(core)，基於弗列斯涅折射原理，我們在波導的偏折處置入一比導光層折射係數還低的區間使光偏折。而此埋藏式波導的製作乃是利用乾蝕刻的方式以鉻(Cr)為蝕刻保護層在SiO2上蝕刻出溝槽。蝕刻出溝槽後再鋪上高分子材料將溝槽平坦化，使之成為我們的導光層。而導光層外部多餘的高分子材料則利用回蝕(etch back)的方法來去除。最後再鋪上一層SOG(Spin On Glass)當成我們的披覆保護層。波導製作完成後在經由兩次8度的偏折後仍然可以保有75% 的傳輸效率。傳輸損耗為0.6dB/cm。
此外，由BPM-CAD的理論模型的計算得知，不同角度的偏折損耗與導光層及披覆層的折射係數有關。即導光層及披覆層的折射係數差值愈大，偏折損耗相對的就會愈小。

Abstract

A buried hybrid waveguide with large angle bend utilizing Fresnel refraction is presented. The waveguide device consists of a polymer core buried in SiO2 cladding on a Si substrate. Large angle bend of the waveguide is achieved based on Fresnel refraction by inserting a low index region into the bend structure. The buried hybrid waveguide was fabricate by dry etching a trench into the SiO2 cladding using Cr as the etch mask. Benzocyclobutene (BCB) polymer was then coated on to the sample to planarize the surface and was used as the guiding core. Etch back was performed to remove the polymer outside the guiding region. The device was completed by passivating the surface with a thin layer of spin on glass (SOG). The normalized transmission loss of the hybrid waveguide with two 8° angle bends is 75%. The propagation loss of the waveguide is 0.6 dB/cm.
In addition, a theoretical model of the bend waveguide is proposed. BPM-CAD is used to calculate the bending loss of the waveguide with different bending angles. The calculated results suggest that a large angle bend can be obtained for a large index different the core and the cladding.

目錄

第一章 簡介 1
第二章 理論模型 7
第一節 埋藏式高分子複合波導之元件結構 7
第二節 埋藏式高分子複合波導之偏折原理 8
第三節 計算結果與討論 12
第三章 波導材料分析與成長 18
第一節 Cr 材料之成長與特性分析 18
第二節 SiO2材料特性分析 19
第三節 高分子材料特性分析 21
第四節 結果與討論 26
第四章 波導元件製作 27
第一節 元件製作流程 27
第二節 製程結果與討論 33
第五章 波導特性與偏折損耗量測 37
第一節 量測系統 37
第二節 量測結果與討論 38
第六章 結論 40
圖目錄

第一章 簡介
圖1.1傳統的偏折式波導 2
圖1.2在偏折處加上一菱鏡結構的波導 2
圖1.3埋藏式波導架構圖 3
圖1.4鈮酸鋰之擴散式波導架構圖 3
圖1.5脊樑式偏折波導上視圖 4
圖1.6脊樑式偏折波導側視圖 4
第二章 理論模型
圖2.1埋藏式波導側邊剖面圖 7
圖2.2波由一介質行進至另一介質之分析 9
圖2.3偏折波導的結構圖 12
圖2.4經BPM-CAD模擬的波導三層結構 12
圖2.5利用相關函數法計算出圖2.4 結構之光場分佈圖 13
圖2.6加上偏折結構與傳統偏折波導傳輸效率之比較 14
圖2.7 Δn改變與傳輸效率的關係 14
圖2.8不同Δn 其能量傳輸效率比較圖 15
圖2.9製程側蝕的容許度誤差計算 16
圖2.10埋藏式波導輸出端的場型分佈圖 16
圖2.11波導經兩次8度偏折後其輸出端的場型分佈圖 17
第三章 波導材料分析與成長
圖3.1保護層材料成長的示意圖 19
圖3.2 SiO2經乾蝕刻後槽溝的SEM圖 20
圖3.3 SiO2乾蝕刻後偏折處的SEM圖 20
圖3.4 Prism Coupler 22
圖3.5 BCB 高分子材料的硬烤條件 24
圖3.6折射係數與溫度的關係圖 24
圖3.7 SiO2溝槽平坦化之後的SEM圖 25
第四章 波導元件之製作
圖4.1曝光顯影後的示意圖 29
圖4.2光阻去除後的示意圖 30
圖4.3乾蝕刻後的示意圖 30
圖4.4 BCB 高分子材料塗鋪的示意圖 31
圖4.5 BCB 固化條件示意圖 31
圖4.6乾蝕刻後的示意圖 32
圖4.7 SOG 塗鋪示意圖 32
圖4.8 SOG 固化條件示意圖 33
圖4.9 Cr 溼蝕刻後的結果 34
圖4.10 SiO2乾蝕刻後的結果 34
圖4.11波導偏折處乾蝕刻後SEM示意圖 35
圖4.12回蝕之後波導的平坦度SEM示意圖 35
圖4.13切刻波導側邊後的SEM示意圖 36
第五章 波導特性與偏折損耗量測
圖5.1量測系統的架設圖 37
圖5.2偏折波導的量測方法 38
圖5.3 分別針對TE與TM波所量出來的偏 折損耗 39
圖5.4理論與實際的量測結果比較 39






















表目錄

第二章 理論模型
表2.1各材料間的折射率 8
第三章 波導材料分析與成長
表3.1高分子材料的特性 21
表3.2旋轉塗佈機轉速與BCB厚度之關係 23

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