臺灣博碩士論文加值系統

由於鉭酸鋰具有較佳的非線性係數，且可承受較大的入射光功率，以及在短波長區段有較高的穿透率，因此被廣泛的應用於雷射與光通訊系統的光波長轉換元件。

本論文探討以雷射加熱基座生長法(LHPG)研製出鉭酸鋰晶體光纖，外加以週期性變換之高壓電場，製作週期性區域極化反轉之鉭酸鋰晶體光纖。在製作的過程中，可觀察到鋰原子受到高溫高壓電場影響而游離並產生氧化鋰，我們並可由實驗結果合理的解釋氧化鋰會影響量測電流以及改變電場分佈，並提出等效電路模型，電流模擬之結果與實驗值接近。最後提出電偶極模型進行感應電流的估算及解釋實驗成果。

在倍頻光學實驗上，可得到基頻光為1542.1 nm有最高的倍頻輸出功率，與理論值1550 nm僅有0.51%的誤差；而以平均功率120 mW，波長1524.2 nm之基頻光入射時，可量測到16.6μW的倍頻輸出，其倍頻轉換效率較以往進展10倍以上。

As a result of larger nonlinear coefficients, high damage threshold, and high transmission for short wavelength, LiTaO3 is broadly used as the nonlinear crystal in laser system and wavelength converter in optical communication systems.

In this thesis, we discuss the growth of periodically poled LiTaO3 crystal fibers without metallic patterns by the use of laser heated pedestal growth (LHPG) method. We observed lithium atoms were ionized by the high temperature and voltage, and they became Li2O during the growth. It can reasonably be explained that the produce of Li2O affects the measurement current and change distribution of the electric field. An equivalent circuit model is established to simulate the experiment data, with good agreement between each other . Finally, a dipole model to estimate the induced current for explaining the experiment result is also obtained.

In the optical experiment, the second harmonic(SH) signal was measured to be peaked at 1542.07-nm fundamental wavelength, and the error is only 0.51% compared with the theoretical value of 1550-nm. And the SH signal was measured to be 16.6μW at 1524.2-nm fundamental wavelength with an 120-mW pump power. The conversion efficiency is ten times more than that in the past.

口試委員審定書 i
致謝 ii
中文摘要 iv
Abstract v
目錄 vi
圖目錄 ix
表目錄 xiii
第一章 緒論 1
第二章 相位匹配原理與週期性區域極化反轉機制 5
2.1 非線性頻率轉換與相位匹配 5
2.2雙折射相位匹配法 14
2.3準相位匹配法 21
2.4 鉭酸鋰晶體結構與特性 25
2.4.1 非線性材料比較 25
2.4.2 鉭酸鋰歷史回顧 26
2.4.3 鉭酸鋰晶體結構 27
2.4.4 鉭酸鋰晶體特性 27
2.5極化反轉機制 31
第三章 準相位匹配晶體光纖之研製 34
3.1 晶纖生長方式 34
3.2 LHPG生長系統架構 38
3.3 外加電場系統架構 41
3.3.1 電場導致極化反轉 41
3.3.2 電極的架設 42
3.3.3 極化反轉週期設計 43
3.4生長系統之控制 44
第四章 電流即時監控實驗 47
4.1極化反轉與感應電流 47
4.2電流量測架構 50
4.3 氧化鋰析出物的影響 51
4.3.1氧化鋰析出物對量測電流的影響 51
4.3.2氧化鋰析出物對電場的影響 53
4.4電極位置對量測電流的影響 55
4.5 電流成份探討與模擬 58
4.5.1 析出物等效電路模型 58
4.5.2 電流模擬與探討 67
4.6 極化反轉感應電流的估算 71
4.6.1有效極化反轉區域長度的估算 71
4.6.2 電偶極極化反轉模型 73
第五章 光學特性量測與結果探討 77
第六章 結論 83
6.1 總結 83
6.2 未來展望 84
參考文獻 85

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