由於光通訊的快速成長與需求，傳輸資訊量每年皆以倍數成長，
加上無水光纖的技術突破，消除了在波長1.4 μm的損耗，使得低損耗
的傳輸波段擴展為1.3 μm ~1.6 μm，再配合分波多工技術，大幅的增
加傳輸資訊量。但要充分發揮這項新技術，還要有光放大器、光纖光
源等元件加以配合。而我們所使用的Cr4+:YAG晶體，自發輻射光譜涵
蓋了整個光通訊波段，且其吸收頻譜在0.9 μm ~1.2 μm波長範圍內，
與目前參鉺光纖放大器所使用的激發光源相容，故非常適合於晶體光
纖放大器之應用。
我們以成功將LHPG方法生長的雙纖衣Cr4+:YAG晶體光纖以光纖
融燒機與通訊用之單模光纖融燒接合，藉由改變融燒參數以得到更小
的插入損耗，目前訊號光(1620 nm)的雙重插入損耗已經降低到3.8
dB。藉由熔燒的影像可對我們微調參數所造成的熔燒結果做定量的
分析，並且針對自發輻射光散逸到內纖衣的狀況來修改模擬程式，以
得到與實際更為吻合的模擬結果，再藉由數值模擬來找出目前淨增益
小於0 dB的原因，並尋找改善的方法，由模擬結果可知，纖心直徑
10 μm且長7.5 cm的Cr4+:YAG晶體光纖，在1 W的激發光源下，可產
生2 dB的淨增益。
未來我們將縮小Cr4+:YAG晶體光纖的直徑至小於10 μm，並且提
昇鉻離子濃度，以期能降低雙邊插入損耗並提昇增益，進而研發出超
寬頻放大器。

The maximum capacity of an optical fiber transmission system 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 1.3 μm to 1.6 μm. The fast increasing demand of communication capacity results in the emergence of wavelength division multiplexing (WDM) technology, which results in the need for wideband optical amplifier. Cr4+:YAG has a strong spontaneous emission that covers 1.3 μm to 1.6 μm. Besides, its absorption spectrum is between 0.9 μm to 1.2 μm, which matches with the pumping source in current erbium doped optical amplifier. Such a fiber is, therefore, eminently suitable for optical amplifier applications.

We have successfully fused the double cladding Cr4+:YAG crystal fiber with single mode fiber by fusion splicer. The crystal fibers are grown by the laser-heated pedestal growth technique. The splicing parameters are optimized to achieve an insertion loss of 3.8 dB. Througth the splicing images, we can quantitatively analyze the splicing results caused by fine tuned parameters, and aimed at the evolution of the ASE, that is dissipated into inner cladding. The simulation program is revised with better fitting. We can find the reason why net gain is under 0 dB by simulation result, and find the way to improve. Numerical simulation indicates that the gain can reach 2 dB at 1 W pump, if the core diameter of the double cladding Cr4+:YAG crystal fiber is reduced to 10 μm.

In the future, we’ll reduce the core diameter of Cr4+:YAG crystal double cladding fiber to less than 10 μm, and enhance the Cr4+ ion concentration to lower the insertion loss after two-sided splicing, Hopefull, super-wideband optical amplifier can be realized.

中文摘要 i
英文摘要 ii
目錄 iii
圖目錄 v
表目錄 viii
第一章 緒論 1
第二章Cr4+:YAG的晶體特性 6
2.1 YAG的晶體結構與特性 6
2.2 Cr4+:YAG的能階模型與吸收及放射頻譜 9
2.3 Cr4+:YAG雙纖衣晶體光纖之生長方法 12
2.4 Cr4+:YAG晶體光纖之結構分析 17
2.5 Cr4+:YAG晶體光纖中之傳輸損耗 19
第三章 超寬頻晶體光纖放大器之研製 25
3.1 Cr4+:YAG晶體光纖端面之研磨拋光 25
3.2 Cr4+:YAG晶體光纖與單模光纖之熔燒 29
3.2.1熔燒方法 29
3.2.2熔燒參數 35
3.2.3熔燒影像分析 42
3.2.4 Cr4+:YAG晶體光纖之熔燒與包覆 46
第四章 放大器之光學特性量測 49
4.1 Cr4+:YAG晶體光纖熔燒後之檢測 49
4.1.1傳播路徑檢測 49
4.1.2插入損耗量測 52
4.2 增益量測實驗架構與結果 57
第五章 理論分析與數值模擬 60
5.1理論模型 60
5.1.1 速率方程式 60
5.1.2 激發光源、訊號光源與ASE之光強度變化 63
5.1.3 ASE功率與訊號光功率的計算 64
5.2 數值模擬分析 65
第六章 結論 69
參考文獻 71
中英對照表 75
附錄:CDFA之模擬程式 78

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