在這最近十年以來，由於光通訊的快速成長與需求，光纖傳輸線每年皆以倍數成長。隨著消除OH-離子光纖的發展，使得可傳輸的波長擴展為1300 nm~1600 nm的低損耗波段。而伴隨著光纖通訊的需求急速增加，亦發展出分波多工技術，此技術是將同一根光纖分成數十個不同的頻道，可以同時傳輸不同波長的訊號光源。這樣的光學傳輸網路系統使得光學元件的光譜頻寬需求也跟著變大。

而利用半導體雷射激發Cr4+:YAG晶纖產生3T2→3A2之自發輻射光譜，涵蓋了1300 nm∼1600 nm整個低損耗通訊頻段，同時YAG晶體亦具有很好的機械特性，適合高功率的激發光源幫浦，因此極具發展超頻寬自發輻射放大光源的潛力。

本論文將LHPG方法生長的Cr4+:YAG晶纖，長度為46.6 mm，以半導體雷射為激發光源，成功的研製出3 dB頻寬為265 nm的超頻寬ASE光源，其功率密度為-22.1 dBm/nm。而未來我們將針對較小的纖心直徑、較長的晶纖、較高的Cr4+摻雜濃度、雙纖衣Cr4+:YAG晶纖、冷卻系統和端面鍍膜等因素加以改善，以期能產生更高的量子轉換效率與ASE輸出功率。

During the last decade, the maximum capacity of an optical fiber transmission line more than doubled every year to match the fast-growing communication need. The technology break through in dry fiber fabrication opens the possibility for fiber bandwidth all the way from 1300 nm to 1600 nm. The fast increasing demand of communication capacity results in the emergence of wavelength division multiplexing (WDM) technology, enabling tens of channels with different wavelengths transmitted simultaneously on an optical fiber. In consequence, it raises the requirement of spectral bandwidth of all the optical components used in the optical transport networking systems.

Cr4+:YAG has potential to meet this demand because its 3T2→3A2 transition has a strong spontaneous emission that just covers the low-loss window of optical fiber. The crystalline host offers a excellent mechanical characteristic. Such a fiber is, therefore, eminently suitable for super-wideband optical source since the required pump power is expected to be higher.

We have successfully demonstrated a diode-laser pumped Cr:YAG crystal fiber ASE light source. The crystal fibers are grown by the laser-heated pedestal growth technique. Using a 46.6 mm-long Cr:YAG single crystal fiber of a 3-dB ASE width of 265 nm and a power spectral density –22.1 dBm/nm was achieved. In the future, to further increase the quantum efficiency and output power we will reduce the core diameter, lengthen the fiber, increase the Cr4+ doping concentration, fabricate double-cladding, coat the fiber facets, and improve the cooling system.

目錄
中文摘要 i
英文摘要 ii
圖目錄 v
表目錄 viii
第一章 緒論 1
第二章 Cr:YAG的晶體特性 5
2.1 Cr:YAG晶體特性分析 5
2.2 Cr:YAG的能階模型與吸收及放射輻射頻譜 8
2.3 Cr:YAG的生長方法 12
2.4 Cr:YAG晶體光纖特性與鉻離子濃度分析 17
2.4.1 Cr:YAG晶纖之晶格分析 17
2.4.2 Cr:YAG晶纖的Cr離子濃度分佈量測 20
2.4.3 Cr:YAG晶纖之Cr3+與Cr4+離子螢光檢測 22
第三章 Cr:YAG晶體光纖之超頻寬自發輻射放大光源之研製 25
3.1 Cr:YAG晶體光纖的包覆與研磨拋光 25
3.2 實驗架構與量測結果 29
3.2.1 端面激發之自發輻射放大光源 29
3.2.2 側面激發之自發輻射放大光源 31
3.3 Pyrex玻璃纖衣Cr:YAG晶體光纖之光學量測 33
3.3.1 Pyrex玻璃纖衣Cr:YAG晶體光纖之傳輸損耗量測 33
3.3.2 Pyrex玻璃纖衣Cr:YAG晶體光纖之ASE量測 37
3.4 雙纖衣Cr:YAG晶體光纖之晶體分析 40
第四章 理論分析與數值模擬 43
4.1 理論模型與數值模擬分析 43
4.1.1 速率方程式 43
4.1.2 激發光源與ASE之光強度變化 45
4.1.3 ASE功率的計算與數值分析 47
4.2 雙纖衣Cr:YAG晶體光纖之設計與數值模擬 51
4.2.1 雙纖衣Cr:YAG晶體光纖之設計 51
4.2.2 雙纖衣Cr:YAG晶體光纖之數值模擬 55
第五章 結論 60
參考文獻 62
中英對照表 64
附錄：ASE功率之模擬程式 67

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