本篇論文將使用八字形光纖雷射共振腔，以摻鉺光纖作為增益介質，透過非線性循環鏡效應產生鎖模光纖雷射，非線性循環鏡相當於一具有強度相關的光學開關，因此可以利用此機制產生雷射脈衝。經示波器所觀察到的脈衝形狀為類矩形形狀，且脈衝寬度會隨者泵激光源功率的增加而變寬，透過調整共振腔內的偏振控制器或是增加泵激光源功率將會產生諧波鎖模，此架構可產生十四階的諧波鎖模。透過在雷射共振腔加入兩個不同波長的薄膜濾波器，並經過適當的光纖彎曲，避免兩個波長光的增益競爭，產生穩定的雙波長脈衝，兩中心波長分別為1550.12 nm與1560.61 nm，且可透過增加泵激光源功率產生二階諧波鎖模。利用單波長的脈衝光源打入以非平衡干涉儀為架構的低同調干涉儀，可透過干涉訊號來辨別感測光纖是否受應力，藉此做為入侵偵測用途。

In this paper, we use erbium-doped fiber as the gain medium to generate mode-locked fiber laser pulses through a nonlinear loop mirror effect in a figure-eight laser resonator. A nonlinear loop mirror is equivalent to an intensity dependent optical switch , which has been used to generate laser pulses. The shape of the pulse is rectangular-like as appearing on the oscilloscope, and the pulse width will increases with the pump power. Harmonic mode-locked pulses can be achieved by adjusting the polarization controller in the cavity or by increasing the pump power. This structure can generate the fourteenth harmonic mode-locked pulses. Stable dual-wavelength pulses can be generated by using two different wavelengths of thin film filters in the laser cavity. Proper fiber bending is used to avoid gain competition between the lasing lights at the two wavelengths. The center wavelengths are 1550.12 nm and 1560.61 nm, respectively, and second harmonic mode-locked pulses can be generated by increasing the pump power. In the second part of the thesis, the mode-locked pulses at one wavelength launched into a low-coherence interferometer based on an unbalanced interferometer. The interference signal can be used to distinguish whether the sensing fiber is disturbed, so we can use it for intrusion detection.

第一章 序論 1
1.1研究背景 1
1.2研究目的與動機 2
1.3文獻回顧 3
1.3.1光纖雷射共振腔 3
1.3.2採用非線性極化旋轉的鎖模光纖雷射 4
1.3.3採用非線性循環鏡的鎖模光纖雷射 5
1.3.4以雙波長鎖模雷射產生兆赫波輻射(Terahertz wave generation through a dual-wavelength mode-locked laser) 6
1.4論文架構 7
第二章 原理與介紹 8
2.1光纖(Optical fiber) 8
2.2光纖耦合器(Fiber coupler) 9
2.3極化控制器(Polarization controller) 10
2.4薄膜濾波器(Thin-Film Filter, TFT) 11
2.5摻鉺光纖以及摻鉺光纖放大器(EDF and EDFA) 12
2.6鎖模 (Mode-lock) 14
2.7克爾效應(Kerr effect) 16
2.8非線性極化旋轉(Nonlinear polarization rotation, NPR) 17
2.9非對稱型耦合之非線性循環鏡 19
2.10對稱型耦合之非線性循環鏡 21
2.11低同調干涉儀 23
第三章 實驗架構 26
3.1八字型共振腔雷射鎖模雷射 26
3.2腔外摻鉺光纖放大器EDFA 27
3.3雙波長鎖模脈衝雷射 28
3.4脈衝雷射用於低同調干涉儀 30
第四章 實驗結果與分析 33
4.1八字形單波長鎖模雷射 33
4.1.1基本鎖模雷射脈衝量測 33
4.1.2基本鎖模雷射經EDFA放大 41
4.1.3諧波鎖模雷射(Harmonic mode lock) 46
4.2雙波長鎖模雷射 59
4.3低同調干涉儀作為防區偵測 72
4.3.1感測光纖中端敲擊 73
4.3.2感測光纖前、後端敲擊 75
第五章 結論與未來方向 79
5.1結論 79
5.2未來方向 80
參考文獻 81

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