近年來由於光通訊需求的快速成長，因而帶動了通訊用1.3 μm~1.6 μm波長雷射光源的發展，摻鉻釔鋁石榴石(Cr4+:YAG)固態雷射將相當有潛力滿足此寬頻之需求，且固態雷射具有高品質輸出模態、壽命長、結構簡單、體積小諸優點，因此其潛力將不容忽視。

本論文採用小尺寸雙纖衣之晶體光纖做為雷射增益介質，在晶體的兩端鍍上光學薄膜做成共振腔，可大幅縮小固態雷射之體積，降低成本，簡化固態雷射架構，同時提高散熱效率。實驗採雷射加熱基座生長法生長晶體光纖，此法不僅可輕易生長出直徑極小之單晶，且生長速度快、耗能低、控制容易，並能夠於玻璃包覆外層加上銅鋁合金包覆來提高散熱效率，將此元件加以研磨、拋光、鍍膜即可製成Cr4+:YAG晶體光纖雷射。同時對晶體光纖中之Cr2O3與CaO摻雜濃度分佈、螢光與折射率分佈、以及傳輸損耗與吸收係數做了量測與分析。

我們得到最低的雷射閾值功率為0.75 mW，小於任何文獻記述掺鉻雷射之閾值功率五百倍以上，斜率效率達到6.9%。能夠產生超低閥值功率是由於低傳輸損耗0.08 dB/cm以及纖心有較高的激發光源強度所致，如此超低閥值的工作條件使得雙纖衣晶體光纖雷射能夠與目前的光通訊系統相容，同時我們也針對所研製之晶體光纖雷射進行模擬與實驗結果做比對。

During last decade, the fast-growing communication need has promoted the development of 1.3 μm~1.6 μm laser light source. The Cr4+ doped YAG solid-state laser has potential to meet this broadband demand. In addition, diode-laser-pumped solid state laser has the merits of high laser beam quality, long lifetime, compact, and simple structure.

In this thesis, crystal fiber was used as the laser gain medium, and coated with optical thin film at its end facets as the laser cavity. Using this configuration, the volume and cost of the laser can be appreciatively reduced, and the heat dissipation can be improved. The laser-heated-pedestal-growth method was used to grow crystal fiber, which can obtain small diameter at very fast rate. Outside the glass clad Cr4+:YAG crystal fiber, Al-Cu alloy was employed as the heat sink to improve heat dissipation. After grinding, polishing, and coating of this device, the Cr4+:YAG crystal fiber laser was fabricated. Some characteristics of Cr4+:YAG crystal fiber, such as the distribution of Cr2O3 and CaO doping concentration, fluorescence intensity, refraction index, propagation loss, and absorption coefficient were measured and analyzed. A record-low threshold of 0.75 mW was achieved. It is more than 500 times lower than any previously reported Cr4+:YAG lasers, and a slope efficiency of 6.9% was obtained. The ultralow-threshold lasing is made possible by the low propagation loss of 0.08 dB/cm and the high pump intensity of the core. Such a low-threshold operation makes the double-clad crystal fiber laser be compatible to present optical communication systems. In the meanwhile, some simulations of the laser output power have been developed to predict the experimental results.

中文摘要 i
英文摘要 ii
致謝 iii
目錄 iv
圖目錄 vi
表目錄 ix
第一章 緒論 1
第二章 Cr4+:YAG晶體光纖雷射原理 5
2.1 晶體特性 5
2.2 電荷補償 14
2.3 能階模型 17
2.4 傳輸模態 20
第三章 晶體光纖生長與元件備製 24
3.1 晶體生長架構及方法 24
3.2 晶體光纖之金屬包覆 32
3.3 元件之研磨與拋光 35
第四章 Cr4+:YAG雙纖衣晶體光纖雷射之特性量測 39
4.1 Cr4+:YAG雙纖衣晶體光纖之成份與螢光分析 39
4.1.1 成份分析 39
4.1.2 折射率與螢光分佈量測 43
4.2 雷射共振腔架構 46
4.3 雷射共振腔之光學鍍膜 48
4.4 Cr4+:YAG雙纖衣晶體光纖雷射之耦光 52
4.5 雷射系統架構與雷射效率分析 54
4.5.1 雷射系統架構 54
4.5.2 實驗結果分析 55
4.6 Cr4+:YAG雙纖衣晶體光纖雷射之極化量測 59
第五章 Cr4+:YAG雙纖衣晶體光纖雷射模擬 61
5.1 雷射理論架構 61
5.2 模擬數值分析 69
第六章 結論 77
參考文獻 80
中英對照表 84
附錄：雷射模擬程式 88

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