具有超高重複率、ps級脈衝寬度的因數諧波鎖模光纖雷射是一項關鍵技術對於發展高位元率全光分時多工通信系統。本研究中，我們發現高階因數諧波鎖模本身具有鎖模力量退化與脈衝振幅不等高的缺點，因此，本論文係以光脈衝注入半導體光放大器進行因數諧波鎖模光纖雷射脈衝品質分析與改進為研究主軸
首先，當因數諧波鎖模階數大於8階時，我們觀察到利用反向光脈衝注入半導體光放大器產生之因數諧波鎖模光纖雷射雷射因調變深度降低產生鎖模力量弱化的情況，並導致連續光泵激效應的產生，經由光譜線寬、脈衝壓縮力量的下降與直流/脈衝振幅比例的上升，可量化1到20階因數諧波鎖模力量與連續光泵激的競爭效應。
為了克服因數諧波鎖模脈衝不等高的缺點，我們分別提出使用1-GHz特殊反向光脈衝與重塑10-GHz增益開關操作下Fabry-Perot脈衝注入半導體光放大器光纖雷射產生增益調變效應，有助分別平整化5-GHz與40-GHz因數諧波鎖模脈衝不等高的缺點，並分別建構光注入鎖模模型去模擬振幅不等高因數諧波鎖模脈衝的增益調變補償機制。當達到振幅平整化因數諧波鎖模輸出，有效的提升訊號雜訊抑制比至45 dB與脈衝振幅抖動量低於10%的臨界值。
避免因數諧波鎖模力量弱化的問題，我們利用2階的fractional Talbot effect引進20-GHz頻率倍頻光脈衝注入半導體光放大器光纖雷射以產生40-GHz因數諧波鎖模脈衝，對比於傳統方式產生4階與40-GHz的因數諧波鎖模光纖雷射，優化的2階fractional Talbot effect結合2階因數諧波鎖模機制有效的增加因數諧波鎖模雷射的調變深度，提供一個較穩定40-GHz因數諧波鎖模脈衝，並改進了開/關消光比與時間抖動量的降低。
最後，我們利用SHG-FROG 解析出10-GHz光固子諧波鎖模光纖雷射的線性與非線性啁啾量，並藉由薛丁格方程模擬10-GHz諧波鎖模光纖雷射系統來萃取出環腔線性色散量，其線性色散量的產生主導光注入諧波鎖模的色散特性。

Rational harmonic mode-locking (RHML) fiber lasers generating picoseconds pulsewidth at high-repetition-rate have emerged as a key component for the high-bit-rate optical time-division multiplexing (OTDM) communication system. In this research, we have discovered higher order RHML semiconductor optical amplifier fiber laser (SOAFL) has the degradation on mode-locking capacity, and an output pulse-train with un-equalized peak amplitudes. Therefore, the main focus of the dissertation is focused on the pulse quality analysis and improvement of RHML-SOAFL via optical pulse injection.
First, we observed the degradation on mode-locked mechanism of the dark-optical-comb injection mode-locked semiconductor optical amplifier fiber laser (SOAFL) at RHML order increases to >8. Such a less pronounced RHML mechanism at higher orders is mainly attributed to the weak mode-locking strength at high RHML orders as compared to continuous-wave (CW) lasing mechanism, which has been quantified by reduction of spectral linewidth and pulse-shortening force, and the ratio of DC/pulse amplitude enhancement for discriminating 1st to 20th-order RHML capability.
To overcome the un-equalized RHML peak intensity, optical injection induced gain modulation of a SOA are demonstrated to equalize the peak intensity of 5-GHz and 40-GHz RHML-SOAFL by using 1-GHz inverse-optical-pulse and a reshaped 10-GHz gain-switching FPLD pulse injection, respectively. The optical injection mode-locking models are constructed to simulate the compensation of uneven amplitudes between adjacent RHML pulse peaks before and after pulse-amplitude equalization. The optimized RHML pulse exhibits a signal-to-noise suppression ratio of 45-dB, and the clock amplitude jitter below the threshold limitation of 10%.
On the other hand, to avoid the mode-locked degradation on RHML, a 2nd-order fractional Talbot effect induced frequency-doubling of 10-GHz optical pulse-train is demonstrated to backward inject a SOAFL for 40-GHz RHML. In comparison with the SOAFL pulse-train repeated at 40-GHz generated by the 4th-order purely RHML process, the optimized 2nd-order fractional Talbot effect in combination with the 2nd-order RHML mechanism significantly enhances the modulation-depth of RHML, thus improving the on/off extinction ratio of the 40-GHz SOAFL pulse-train. Such a new scheme also provides a more stable 40-GHz RHML pulse-train from the SOAFL with its timing jitter reduce.
Finally, we established a SHG-FROG to distinguish linear and nonlinear chirp of 10-GHz soliton HML-SOAFL, and further extracted intra-cavity linear dispersion via simulation of Schrodinger equation. After the procedure, the linear chirp almost dominates chirp characteristics for optical pulse injection HML-SOAFL system.

誌謝 iii
中文摘要 v
English Abstract vi
List of Figures xi
Chapter 1 Introduction 1
1.1 Theories of mode-locking, harmonic mode-locking, and rational harmonic mode-locking 1
1.2 Rational harmonic mode-locking fiber laser 3
1.3 Peak-equalized RHML fiber laser 4
1.4 Fractional Talbot effect induced temporal high repetition-rate optical pulse generation 5
1.5 Research motivation 6
1.6 The origination of dissertation 7
References 7
Chapter 2 Investigation of RHML pulse quality in a semiconductor optical amplifier fiber laser under dark-optical-comb injection 13
2.1 Historical review 13
2.2 Experimental configuration of dark-optical-pulse injection induced 20th-order RHML pulse-train 14
2.3 Pulse quality diagnosis in time and frequency domains between HML and 20th-order RHML pulse-train conditions 16
2.4 Relationship of RHML order and frequency chirp after linear dispersion compensation 21
2.5 Summary 26
References 27
Chapter 3 Pulse-amplitude-equalization (PAE) of RHML-SOAFL via optical pulse injection induced gain-reshaping of a SOA 30
3.1 Historical review 30
3.2 Experimental Configurations and concepts 33
3.2.1 Generation of 5th-order peak-equalized RHML-SOAFL pulse-train by reshaping 1-GHz dark-optical-comb 33
3.2.2 PAE in a 40-GHz RHML-SOAFL pulse-train using reshaping 10-GHz gain-switching FPLD pulse-train 35
3.3 Theoretical simulations of optical pulse injection and SOAFL gain-profile for peak-equalized RHML pulse-train 38
3.3.1 Peculiar dark-optical-comb injection 38
3.3.2 Double-peak gain-switching FPLD pulse-train injection 41
3.4 Performance evaluations of peak-equalized RHML pulse-train via peculiar dark-optical-comb injection 44
3.5 Performance discussions of 40-GHz RHML pulse-train with PAE via double-peak pulse injection 48
3.6 Summary 55
References 56
Chapter 4 Construction of 40-GHz RHML-SOAFL pulse-train via fractional Talbot effect (FTE) induced frequency-doubling pulse-train injection 59
4.1 Historical review 59
4.2 Experimental configuration of repetition-rate doubling pulse injection for 40-GHz RHML-SOAFL by employing 2nd-order FTE 61
4.3 Simulation results of pulsewidth broadening in DCF for initiating FTE 63
4.4 Basic features and frequency chirp compensation of FTE after propagating through a 4-km long DCF 65
4.5 Quality enhancement of 40-GHz RHML-SOAFL pulse-train by integrating 2nd-order RHML with 2nd-order FTE 69
4.6 Summary 73
References 74
Chapter 5 Chirp characteristic of 10-GHz harmonic mode-locking SOAFL using second harmonic generation frequency resolved grating 77
5.1 Historical review 77
5.2 Experimental configuration of 10-GHz soliton HML-SOAFL 79
5.3 Linear and soliton pulsewidth compression 80
5.4 Chirp characteristics of 10-GHz soliton SOAFL using SHG-FROG 82
5.5 Simulation configuration of Schrodinger equation for 10-GHz soliton HML-SOAFL 85
5.6 Summary 89
Reference 90
Chapter 6 Conclusion 92
作者簡介 94

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