臺灣博碩士論文加值系統

近年來由於光通訊產業的蓬勃發展，使得通訊傳輸上頻寬的需求與日俱增，加上無水光纖技術的突破，使得光通訊用可使用的頻寬拓展為1.3-1.6 μm。以雷射加熱基座生長法生長的Cr4+:YAG雙纖衣晶體光纖(double-clad crystal fiber; DCF)，可利用雷射激發光激發足以涵蓋整個通訊波段(1.3-1.6 μm)的自發輻射頻譜，適合發展寬頻光放大器、放大自發輻射(amplified spontaneous emission)光源及可調波長固態雷射(tunable solid-state laser)、生醫檢測光源(optical coherence tomography; OCT)之潛力。
本論文為使用電子槍直接於具異質結構(heterostructure)之摻鉻釔鋁石榴石雙纖衣晶體光纖端面製鍍上介電材質薄膜。藉此成功於晶體光纖端面上蒸鍍上對自發輻射光高反射之介電材質薄膜，用以反射背向放大自發輻射光，提高輸出端之功率。藉由雙向激發架構將輸出端之總放大自發輻射功率提高至1.7 mW(晶纖長度為9.5 cm)，比較晶體光纖未製鍍薄膜前之放大自發輻射功率提升1.6倍。光放大器研製方面，採用雙向激發架構並在其晶體光纖一端製鍍高反射膜層使訊號達到雙次傳輸(晶纖長度為8.7 cm)，產生訊號(1.4 μm)增益為3.7 dB，系統淨增益達到-0.7 dB。此外，我們亦成功於晶體光纖兩端面製鍍上光學薄膜，形成穩定雷射共振腔，在室溫下有最低的雷射閾值功率為96 mW(晶纖長度為1.6 cm)，斜率效率達到6.9%，此掺鉻雷射閾值功率小於任何文獻記述之四倍以上。

Recently, with the escalating demands for optical communications, the need for bandwidth in optical communication network has increased. The technology breakthrough in dry fiber fabrication opens the possibility for fiber bandwidth from 1.3 to 1.6 μm. Cr4+:YAG double-clad crystal fiber (DCF) grown by the co-drawing laser-heated pedestal growth method has a strong spontaneous emission spectrum from 1.3 to 1.6 μm. Such fiber is, therefore, eminently suitable for broadband optical amplifier, amplifier spontaneous emission (ASE) light source, tunable solid-state laser, and optical coherence tomography (OCT) applications.
In this thesis, multilayer dielectric thin films were directly deposited by E-gun coating onto the end faces of the heterostructure Cr4+:YAG DCF. In this way we have successfully improved the extracted ASE power by the high reflection (HR) coatings. The backward ASE in the fiber reflected and propagates with gain through the fiber in the forward direction. In dual-pump scheme, as much as 1.7 mW power (DCF length is 9.5 cm) of collimated output ASE was achieved. The dual-pump scheme and HR thin films provided 1.6 time improvements of the ASE output power. For broadband optical amplifier in dual-pump and double-pass scheme, a 3.7-dB gross gain and a 0.7-dB net loss (DCF length is 8.7 cm) at 1.4-μm signal wavelength have been successfully developed with HR coatings onto one of the Cr4+:YAG DCF end faces. In addition, we have successfully developed the Cr4+:YAG DCF fiber laser by direct HR coatings onto fiber end faces. A record-low threshold of 96 mW (DCF length is 1.6 cm) with a slope efficiency of 6.9% was achieved at room temperature. It is more than four times lower than any previously reported Cr4+:YAG lasers.

中文摘要 i
英文摘要 ii
目錄 iii
圖目錄 v
表目錄 ix

第一章 緒論 1
第二章 光學薄膜之基本原理 3
2.1 光學薄膜之膜特徵矩陣 3
2.2 光學薄膜材料特性與光學常數分析 8
2.3 膜成長理論 18
2.4 光學薄膜之電場分佈 20
第三章 電子槍蒸鍍系統架構及光學薄膜檢測儀器之原理 22
3.1 電子槍蒸鍍系統 22
3.2 光學薄膜檢測儀器 30
第四章 Cr4+:YAG雙纖衣晶體光纖之光譜特性及元件製備33
4.1 晶體光纖生長架構與方法 33
4.2 Cr4+:YAG雙纖衣晶體光纖之光譜特性 39
4.3 樣品包覆及端面處理 48
4.3.1光放大器及放大自發輻射樣品製備 48
4.3.2 雷射樣品製備 54
第五章 Cr4+:YAG雙纖衣晶體光纖雷射、光放大器及放大自發輻射之端面鍍膜與光學特性量測 58
5.1 薄膜於晶體光纖端面出現之問題與處理 58
5.2 雷射之特性量測 61
5.3 光放大器之增益量測 71
5.4 放大自發輻射特性量測 77
5.5 光學薄膜之微觀分析 81
第六章 結論 88

參考文獻 90
中英對照表 93

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