本論文介紹一種使半導體雷射線寬變窄的系統。使用外部光纖雷射共振腔來回授光到半導體雷射裡的方式，將原本線寬為MHz級的半導體雷射變窄至<1kHz，並實現單縱模窄線寬雷射。外部光纖雷射共振腔包含雙耦合光纖環形共振器(DCFR)，藉由跳接線的端面反射，讓DFB(Distributed Feedback)雷射光不斷經過DCFR，並使部分的光回授到DFB雷射腔中，窄化半導體雷射的線寬。
在本研究中，DCFR扮演很重要的角色，提供其窄帶通濾波器的特性，是使線寬變得更窄的關鍵。接著探討不同耦合比DCFR對雷射線寬的影響，隨著耦合比增加，線寬會越窄，透過自延遲外差法量測，此雷射最窄線寬可來到300Hz。我們認為這是獲得超窄線寬雷射之具有成本效益的方法。

In this paper, we provide a system for narrowing the linewidth of a semiconductor laser. The external fiber laser resonator is used to feedback the light to the semiconductor laser, so that the original MHz linewidth of the semiconductor laser is reduced to<1kHz, becoming a narrow linewidth laser. The external fiber laser resonator contains a dual-coupler fiber ring resonator (DCFR), which allows the DFB laser light to pass through the DCFR in a narrow band. The laser light is then reflected back inside the DFB laser by the end face of the fiber connector through the DCFR. Through this external fiber laser resonator, we observed the narrowing of the linewidth of the laser light.
In this study, DCFR plays an important role in providing its narrow bandpass filter characteristics, which is the key to making the linewidth narrower. Then, the effect of different coupling ratios of DCFR on the laser linewidth is investigated. As the coupling ratio increases, the linewidth becomes narrower. The narrowest linewidth of this laser was measured to be 300 Hz by using the delayed self-heterodyne method. We believe this is the cost-effective method for obtaining super narrow linewidth lasers.

摘要 I
ABSTRACT II
致謝 III
目錄 IV
圖目錄 VI
第一章 序論 1
1.1 論文架構 1
1.2 研究背景 1
1.3 研究動機與目的 2
1.4 文獻回顧 3
1.4.1 光纖線型共振腔雷射 3
1.4.2 光纖環形共振腔雷射 4
1.4.3 採用自注入鎖定的DFB半導體雷射 6
第二章 基本原理 8
2.1 分佈回饋式(Distributed Feedback，DFB)雷射 8
2.2 雙耦合光纖環形共振器(Double-Coupler Fiber Ring Resonator，DCFR) 9
2.3 外腔式半導體雷射 15
2.4 光纖雷射(Fiber Laser) 16
第三章 實驗架構 19
3.1 外部光纖雷射共振腔回授之窄線寬DFB半導體雷射 19
3.2 實驗元件 22
3.2.1 DFB (Distributed Feedback)半導體雷射 22
3.2.2 摻鉺光纖(Erbium-Doped Fiber，EDF) 23
3.2.3 密集分波多工器(Dense Wavelength Division Mutiplexer，DWDM) 24
3.3 量測雷射線寬 25
第四章 實驗結果與分析 28
4.1 DFB (Distributed Feedback)半導體雷射量測 28
4.2 外部光纖雷射共振腔回授之窄線寬DFB雷射量測 31
4.3 雙耦合光纖環形共振器參數 36
第五章 結論與未來方向 49
5.1 結論 49
5.2 未來方向 50
參考文獻 51

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