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 μm~1.6 μm。伴隨著光纖通訊的頻寬需求急速增加，亦發展出分波多工技術，可同時讓數上百個頻道同時傳輸，所以需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 μm ~1.6 μm的範圍，且其吸收頻譜在0.9 μm~1.2 μm波長範圍內，與目前摻鉺光纖放大器0.98 μm激發光源相容，故非常適合於晶體光纖放大器之應用。

本論文以雷射加熱基座生長法製備的超寬頻雙纖衣Cr4+:YAG晶體光纖放大器的研發進一步分析與討論。我們藉由數值模擬分析可以得到在端面鍍上高反射膜層讓訊號光達到雙次傳輸效果下，產生雙倍的增益。目前以端面對接耦合方式SMF28-Cr4+:YAG DCF-SMF28 (DCF即雙纖衣晶體光纖)架構，雙向各輸入1.3 W激發光功率及雙向兩次訊號傳輸時，可得到淨增益0 dB。本論文亦對雙纖衣Cr4+:YAG晶體光纖做完整的數值模擬分析，並與實驗結果比對，進而找出實驗上的改善方向。此外，本論文也對Cr4+:YAG晶體光纖作系統量測，做串音干擾之探討。

未來我們將試著藉由cladding pump或 side pump取代core pump架構，用波長925 nm取代波長1064 nm作為泵浦光源、用CuO側鍍和Cr2O3側鍍來減少內纖衣的吸收和增加纖心的吸收；同時我們將嘗試生長纖心直徑更小的光纖並拉長其長度，以改善元件的增益。

Due to the fast growing communication need, the required capacity of the optical fiber network has been more than doubled every year. The technology breakthrough in dry fiber fabrication opens the possibility for fiber bandwidth 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, enabling tens or even hundreds of channels with different wavelengths transmitted simultaneously on an optical fiber, which results in the need for ultra-broadband optical amplifier. Cr4+:YAG has a strong spontaneous emission spectrum covers from 1.3 μm to 1.6 μm. In addition, its absorption spectrum is between 0.9 μm to 1.2 μm, which matches the pumping wavelength of current erbium doped optical amplifier. Such fiber is, therefore, eminently suitable for optical amplifier applications.

In this thesis, we introduce the development of ultra-broadband optical amplifier using the Cr4+:YAG double-clad crystal fiber, which is grown by the laser-heated pedestal growth (LHPG) technique. Try to use passive tence theoretical models and numerical simulations to know we can get more than 2 dB gross gain when signal propagations two times in Cr4+:YAG double-clad crystal fiber. With the butt-coupling method, a net gain of 0.0 dB is demonstrated at 1.3W bi-directional pump power and signal double pass in Cr4+:YAG double-clad crystal fiber at present.

In the future, in order to reduce pump excited-state-absorption. We attempt to use clad-pump or side-pump scheme instead of core-pump scheme, to choose pumping wavelength at 925 nm instead of 1064 nm and to use side deposition of Yb2O3 and CuO . At the same time, we will continue to fabricate small-core-diameter Cr4+:YAG DCF to achieve a single-mode fiber and to extend its length to improve gain performance.

中文摘要 i
英文摘要 ii
致謝 iii
目錄 iv
圖目錄 vi
表目錄 x
第一章 緒論 1
第二章 Cr4+:YAG雙纖衣晶體光纖的特性 9
2.1 Cr4+:YAG晶體之結構與特性 9
2.2 Cr4+:YAG的能階模型與吸收及放射頻譜 15
2.3 Cr4+:YAG雙纖衣晶體光纖之生長方法 18
2.4 Cr4+:YAG雙纖衣晶體光纖之成份分析 26
2.5 Cr4+:YAG雙纖衣晶體光纖中之信號傳輸 29
第三章 理論分析與數值模擬 39
3.1理論模型 39
3.1.1速率方程式 39
3.1.2泵浦光源、訊號光源與ASE之光強度變化 41
3.2數值模擬分析 42
第四章 Cr4+:YAG雙纖衣晶體光纖放大器低溫量測 52
4.1低溫自發性輻射架構與結論 52
4.1.1低溫自發性輻射架構 52
4.1.2低溫自發性輻結論 58
4.2低溫增益架構與結論 59
第五章 Cr4+:YAG雙纖衣晶體光纖放大器樣品製備 62
5.1 Cr4+:YAG雙纖衣晶體光纖之散熱封裝 62
5.2元件之研磨與拋光 64
第六章 Cr4+:YAG雙纖衣晶體光纖放大器之特性量測 70
6.1 Cr4+:YAG雙纖衣晶體光纖之耦光 70
6.2插入損耗量測 73
6.2.1輸入端插入損耗 74
6.2.2雙邊插入損耗 75
6.3增益實驗量測架構與結果 79
6.3.1 系統增益 79
6.3.2 雙向泵浦Cr4+:YAG雙纖衣晶體光纖 81
6.3.3 雙向泵浦且雙次傳輸量測 83
6.4串音量測 89
6.4.1 串音 89
6.4.2 串音之定義 90
6.4.3 串音量測架構與結果 91
第七章 結論和未來展望 94
參考文獻 99
中英對照表 103
附錄：CDFA之模擬程式 107

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