由於光纖網路與電子商務的蓬勃發展，使光通訊網路的頻寬需求大幅提升。而在美國Lucent公司在近幾年開發出無水光纖之後，以1400 nm為中心波長的新傳輸頻寬於焉誕生。然而，相對於該波段的各種光通訊系統所需要的主、被動元件，包括雷射光源及光放大器等等至今卻仍在開發當中。本論文便是以Cr4+:YAG晶體光纖，其輻射頻寬可達1200 nm至1600 nm的超寬頻自發輻射放大(amplified spontaneous emission, ASE)光源為主題，進行其相關理論模擬與實驗之研究。

本實驗室先前已開發出以側邊激發架構，在11 W的980 nm激發光源底下，可輻射出0.65 mW功率的ASE光源。此外，在端面激發架構方面，則可同樣在11 W的1064 nm激發光源下，輻射出2.45 mW的ASE光源。本篇論文則是在此基礎之上，繼續在Cr4+:YAG晶體光纖的材料特性分析、ASE理論模擬和各種相關實驗方面繼續加以探討。另外除了在前述的側邊及單向的端面激發架構以外，本論文亦在雙向的端面激發架構上進行了理論模擬和實驗的規劃，以期在未來本實驗室全光纖Cr4+:YAG開發完成後，進行各項雙向激發架構理論與實際上的驗證。

Owing to the increasing demand on the telecommunication bandwidth and the advent of the OH--free dry fiber developed by Lucent Technology, a new transmission bandwidth for the fiber optical communication which is centered around 1400 nm has been created in recent years. However, the corresponding light sources, optical amplifiers and other devices needed in the new transmission window are still under development. This thesis is to dissert with respect to the Cr4+:YAG crystal fiber based ASE (amplified spontaneous emission) light sources which emit light with broadband wavelengths from around 1200 nm to 1600 nm.

Our previous study showed that side-pumping configuration can achieve a maximum ASE power of 0.65 mW with a pump power of 11 W at 980 nm in wavelength, whereas the end-pumping configuration successfully generated an optimum ASE power of 2.45 mW with a pump power of 11 W using a 1064-nm Yb fiber laser. This thesis reviewed the Cr4+:YAG material and studied on the single and double-pumping configuration of ASE light source, numerical simulations of the L-I curve of both configurations, and of the emission and the gain spectrum of the material, plus the introductions of the experiments needed for the simulations will be reported.

致謝
中文摘要 i
英文摘要 ii
內容目錄 iii
圖目錄 v
表目錄 viii

第一章 緒論 1

第二章 寬頻光源 3
2-1 各種寬頻光源 3
2-2 ASE寬頻光源 5
2-3 Cr4+:YAG 晶體光纖的研究與發展 10
2-3.1 歷史回顧 10
2-3.2 單纖衣與雙纖衣結構Cr4+:YAG晶體光纖 11

第三章 理論模型 16
3-1 速率方程式 16
3-2 單向激發架構理論模型 19
3-2.1 激發態電子密度推導 19
3-2.2激發光源強度變化推導 21
3-2.3 ASE強度變化推導 22
3-3 雙向激發架構的理論模型 24
3-4 單向及雙向激發架構放射頻譜的理論模型 26
3-5 ASE增益理論模型 29
3-6 模擬參數設定 29

第四章 雙纖衣Cr4+:YAG晶體光纖自發輻射光源實驗 32
4-1 晶體的研磨與拋光 32
4-2 折射率量測實驗 34
4-3 吸收頻譜量測實驗 35
4-3.1 Cut-Back Method 36
4-3.2 吸收頻譜量測實驗討論 37
4-3.3 Cr4+:YAG下能階吸收問題討論 39
4-4 ASE功率量測 41
4-5 雙向激發架構的實驗規劃 44

第五章 模擬結果與討論 45
5-1 單向激發架構ASE L-I Curve 45
5-1.1 最佳晶纖長度模擬 46
5-1.2 傳輸損耗與ASE強度關係模擬 46
5-1.3 吸收係數與ASE強度關係模擬 47
5-2 雙向激發架構ASE L-I Curve 48
5-3 Cr4+:YAG自發輻射頻譜模擬 50
5-4 Cr4+:YAG ASE增益頻譜模擬 53

第六章 結論與未來展望 54

參考文獻 58

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