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，加上消除OH－離子光纖的技術突破，使得低損耗波段可傳輸的波長擴展為1.3 mm~1.6 mm。伴隨著光纖通訊的需求急速增加，亦發展出分波多工技術，但仍要有光放大器加以搭配，才能充分發揮這項新技術。Cr4+:YAG晶體，其自發輻射光譜涵蓋了1.3 mm ~1.6 mm的範圍，且其吸收頻譜在0.9 mm~1.2 mm波長範圍內，與目前摻鉺光纖放大器0.98 mm激發光源相容，故非常適合於晶體光纖放大器之應用。

本論文將LHPG方法生長的雙纖衣Cr4+:YAG晶體光纖以光纖熔燒機與通訊用之單模矽光纖熔燒接合，藉由改變熔燒參數以得到更小的插入損耗，目前訊號光(1470 nm~1640 nm)的插入損耗已由4 dB降到1 dB以下。此外，雙纖衣Cr4+:YAG晶體光纖纖心直徑的起伏，會造成光在傳播時有額外的損耗，導致增益下降，本論文將探討可接受的晶纖纖心直徑起伏大小，最後再對整個光學系統做模擬，讓我們往後在實驗前即可先預估結果，並可與實驗結果互相比較，進而找出實驗上要改善的地方。藉由數值模擬，可知-30 dBm的1380 nm訊號光在晶纖纖心直徑為5 mm，且晶纖長度為80 cm的條件下，以0.5 W的激發光源激發，可產生37.2 dB的增益。

未來我們將針對通訊用之單模矽光纖與雙纖衣Cr4+:YAG晶體光纖直徑匹配、熔燒處折射率漸近變化、較高的Cr4+摻雜濃度雙纖衣Cr4+:YAG晶纖等因素加以改善，以期能得到更高的增益。

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 mm to 1.6 mm. 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 mm to 1.6 mm. Besides, its absorption spectrum is between 0.9 mm to 1.2 mm, 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 below 1 dB. Since, the core diameter tapering will increase the propagation loss and reduce the gross gain. Adiabatically tapered fiber is discussed. Simulations are performed to predict the loss, and compare with the experimental results, then find out the way to improve the gross gain. Numerical simulation indicates that the gross gain could reach 37.2 dB at 0.5 W pump, if the core diameter of the double cladding Cr4+:YAG crystal fiber is reduced to 5 mm.

In the future, in order to increase gross gain we will improve the mode matching between the cores of single mode fiber and the double cladding Cr4+:YAG crystal fiber. Gradual change of the refractive index at the splicing region as well as high Cr4+ doping concentration can also improve the gross gain.

中文摘要
英文摘要
目錄
圖目錄
表目錄
第一章 緒論
第二章 雙纖衣Cr4+:YAG晶體光纖的特性
2.1 YAG的晶體結構與特性
2.2 Cr4+:YAG的能階模型與吸收及放射頻譜
2.3 雙纖衣Cr4+:YAG晶體光纖的生長方法
2.4雙纖衣Cr4+:YAG晶體光纖之晶體分析
2.5雙纖衣Cr4+:YAG晶體光纖中之傳輸
第三章 雙纖衣Cr4+:YAG晶體光纖放大器之研製
3.1 雙纖衣Cr4+:YAG晶體光纖端面之研磨拋光
3.2 雙纖衣Cr4+:YAG晶體光纖與單模光纖之熔燒
3.2.1熔燒方法
3.2.2 熔燒參數
3.2.3 雙纖衣Cr4+:YAG晶體光纖熔燒與包覆
第四章 雙纖衣Cr4+:YAG晶體光纖放大器之量測
4.1 雙纖衣Cr4+:YAG晶體光纖熔燒後之檢測
4.1.1傳播路徑檢測
4.1.2 插入損耗量測
4.2增益量測實驗架構與結果
第五章 理論分析與數值模擬
5.1理論模型
5.1.1 速率方程式
5.1.2 激發光源、訊號光源與ASE之光強度變化
5.1.3 ASE功率與訊號光功率的計算
5.2 數值模擬分析
第六章 結論
參考文獻
中英對照表
附錄

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