本論文係少數模態摻鉻晶體光纖之研製與量測，利用雷射加熱基底生長法(laser heated pedestal growth, LHPG)成長摻鉻晶體光纖，搭配抽絲塔技術研製之高折射率玻璃(SCHOTT N-SF57)毛細管，然後將高
折射率毛細管包覆晶體光纖，再利用LHPG法將兩者緊密結合，其可
將纖芯與纖衣的折射率差縮小至10-2數量級以下，成為少數模態摻鉻晶體光纖，達到少數模態(few-mode)LP11的傳輸模態，大幅降低激發功率閥值(pumping threshold)，減少熱能產生並提高能量使用效率。
Cr4+:YAG 高折射率纖衣晶體光纖經由螢光量測可知螢光頻譜與
Cr4+:YAG 晶棒幾乎相同，頻譜範圍為1.2mm~1.6mm。在毛增益特性實驗量測，3.8cm 之Cr4+:YAG 高折射率纖衣晶體光纖，利用單端激發的架構，信號光波長為1.4mm，激發光波長為1.06mm，在激發光功率240mW時，可得到2.1dB 之毛增益；另外，若利用雙向激發的
架構從兩端注入幫浦光來提升激發效率，在激發光功率240mW 時，其毛增益可達2.79dB。
相較於先前研製纖心直徑2mm之少數模態Cr4+:YAG雙纖衣晶體光纖，Cr4+:YAG 高折射率纖衣晶體光纖可大幅降低生長難度及生長時間，故可生長較長的光纖來提高光纖中所含的鉻離子數，並可在較大纖芯得到少數模態的傳輸，改善其增益特性，並更因擁有較大的纖心直徑，可提升光纖在系統上的耦光效率，降低插入損耗，對於未來應用於寬頻光源以及光纖放大器具有發展潛力。

In this study, a few-mode chromium doped yttrium aluminum garnet(Cr4+:YAG) crystalline fiber with high-index glass cladding has been demonstrated by employing laser heated pedestal growth(LHPG) and drawing-tower method. The 38μm single crystal Cr4+: YAG fiber was fabricated by modified LHPG and inserted into a capillary of N-SF57 high-index glass with the inner and outer diameters of 70/260μm fabricated by fiber drawing tower. Then, a CO2 laser beam was focused and shone around the capillary in order to heat it up to collapsing the
tightly-fitted glass capillary. The refractive index difference between core and cladding can be reduced below 10-2. Few-mode group LP11 can operate at 1550nm and 1400nm that were verified by far-field pattern. Few-mode propagation can significantly reduce the threshold of pump power that helps to eliminate heat effect and increase fluorescence efficiency in comparison with the multimode propagation.
The fluorescent spectrum of few-mode high index glass cladded Cr4+:YAG fiber(HICCDF) show that a near-infrared broadband emission from 1.3-1.6μm which was almost the same as Cr4+:YAG rod. The gross gain of HICCDF in 3.8cm length was 2.1dB with single pumped power of 240mW. The pumping architecture was modified to dual pumping that the fiber can be pumped more efficient. The gross gain of HICCDF can improve to 2.79dB with dual pumped power of 240mW.
In comparison with few-mode small core double-clad Cr4+:YAG fiber(DCF), HICCDF was able to grow into longer length. It indicated that HICCDF can improve the gain property by raising the concentration of Cr4+-ion. The insertion loss can also be reduced by larger core diameter
of HICCDF. According to the above, HICCDF has potential to be developed as a broadband laser and an optical fiber amplifier.

目錄
中文摘要 iii
英文摘要 iv
目錄 v
圖目錄 vii
表目錄 x
第一章 緒論 1
1.1 研究背景 1
1.2 研究動機與目的 3
1.3 論文架構 6
1.4 參考文獻 7
第二章 Cr4+:YAG晶體光纖特性分析 8
2.1 釔鋁石榴石的特性 8
2.2 Cr離子在YAG補償特性 12
2.3 Cr4+:YAG能階模型及吸收射頻譜 16
2.4 Cr4+:YAG高折射率纖衣晶體光纖傳輸特性 19
2.5 退火對Cr4+:YAG光學特性影響 23
2.6 參考文獻 27

第三章 Cr4+:YAG高折射率纖衣晶體光纖製程 30
3.1 Cr4+:YAG晶體光纖之生長 30
3.2 晶體光纖端面之研磨拋光 43
3.3 參考文獻 48
第四章 Cr4+:YAG高折射率纖衣晶體光纖特性量測 49
4.1 反射螢光量測 49
4.2 折射率量測 52
4.3 遠場圖形量測 54
4.4 增益特性量測 56
4.5 插入損耗量測 61
4.6 參考文獻 61
第五章 結論 63

第一章
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第三章
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第四章
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[6] 黃光瑤 博士論文, “摻鉻釔鋁石榴石晶體光纖之生長系統改良”, 2009.