臺灣博碩士論文加值系統

二極體雷射泵激之固態雷射，以其體積小、效率高及容易操作等特性，是近年來雷射技術發展的幾個重要課題之一。在這類的雷射中，Nd:YVO4以其對一廣譜寬泵激光的高吸收係數，以及大的激發放射截面積等優異特性，是極具應用潛力的微型雷射材料，而成為研究的焦點。
本實驗旨在研製一以高功率、光纖耦合二極體雷射泵激之Nd:YVO4雷射。除了測量Nd:YVO4晶體的吸收特性，也量測其光致螢光。以一熱鏡補償二鏡腔終端泵激Nd:YVO4（3mm×3mm×3mm， 1% Nd3+ doped），在吸收之泵光（波長為804.5 nm）功率為10.7 W時，得到5.2 W之1064 nm雷射輸出，等效之光對光轉換效率為48.6 %，雷射輸出之斜率效率為52 %。同時，量測之腔內損耗約為4.5%。
以KTP進行腔內倍頻方面，量測了KTP晶體（3mm×3mm×5mm）之角度與溫度對倍頻效率之影響。以全反鏡-Nd:YVO4-KTP之結構，在吸收泵光功率為8.5 W時，得到540 mW之532 nm綠光輸出，光轉換效率為6.4 %。我們相信，若有適當的泵激光源與KTP晶體，這種結構可以得到1 W以上的532 nm綠光。

Because of its compactness, high efficiency and easy operation, laser diode pumped solid-state laser become one of the most attractive topics in recent laser technology research. Among the solid-state lasers, Nd:YVO4, a minilaser material with high application potentials, with its high absorption coefficient to a broad bandwidth pumping source and large simulated emission cross-section, has become the focal point of the laser field.
The purpose of this research is to build a high power, fiber-coupled diode-pumped, all solid-state Nd:YVO4 laser. In order to fully understand Nd:YVO4’s spectroscopy, the research provides the measurements of the Nd:YVO4’s absorption coefficient and photoluminescence. Using a thermal lensing compensation two-mirror end-pumped Nd:YVO4(3mm×3mm×3mm, Nd3+ doped 1%) scheme, with the absorption pump power at 10.7-W(wavelength 804.5nm), the result of 5.2-W 1064-nm laser output power, 48.6% effective optical to optical conversion efficiency, 52% laser output slope efficiency are obtained. The cavity loss is about 4.5%.
As of the intracavity doubling frequency with KTP, the effect of KTP angle and temperature on doubling frequency efficiency is measurement. With the input mirror-Nd:YVO4-KTP structure, at 8.5-W absorption pump power, the result of 540-mW green laser output power and 6.4% optical conversion efficiency are obtained. The conclusion, therefore, is that, using a proper pumping source and a KTP crystal in the above structure, the result of over 1-W 532nm output power should be obtained.

1. 簡介………………………………………………………………….1
1.1.回顧………………………………………………………………1
1.2. Nd:YVO4固態雷射………………………………………………2
1.3. 腔內倍頻之固態雷射………………………………………….3
1.4. 論文架構……………………………………………………….5
2. 固態雷射基本理論…….……………………………………………7
2.1. 光束與高斯光學……………………………………………….7
2.2. 雷射能階……………………………………………………….9
2.2.1. 反轉分佈與熱平衡……………………………………….9
2.2.2. 穩態之雷射能階………………………………………….10
2.3. 兩鏡式雷射共振腔…………………………………………….12
2.4. 熱鏡補償共振腔……………………………………………….13
2.4.1. 熱鏡效應………………………………………………….13
2.4.2. 熱鏡補償共振腔………………………………………….14
2.5. 雷射閾值與腔的損耗………………………………………….15
2.5.1. 雷射閾值………………………………………………….15
2.5.2. 腔之損耗………………………………………………….16
(一) Findlay-Clay 量測法…………………………………..16
(二) John-Caird量測法……………………………………….17
3. Nd:YVO4晶體特性之量測.………………………………………….18
3.1. Nd:YVO4之光譜特性…………………………………………..18
3.2. 二極體雷射出光波長之量測………………………………….19
3.2.1. 二極體雷射波長量測之步驟…………………………….19
3.2.2. 二極體雷射波長量測之結果…………………………...20
3.3. Nd:YVO4晶體特性之量測……………………………………..21
3.3.1. Nd:YVO4晶體吸收特性之量測…………………………..21
(一) 簡介……………………………………………………….21
(二) 實驗架設與量測結果之討論…………………………….22
3.3.2. Nd:YVO4晶體輻射光譜特性之量測……………………..24
(一) 簡介……………………………………………………….24
(二) Nd:YVO4晶體輻射光譜特性之量測………………………24
3.3.3. 結果與分析………………………………………………25
4. 二極體雷射泵激Nd:YVO4雷射.….………………………………..28
4.1. 簡介…………………………………………………………..28
4.2. 泵激光源……………………………………………………..28
4.3. Nd:YVO4雷射………………………………………………….29
4.4. 腔長與輸出功率之關係……………………………………..30
4.4.1. 腔長優化之實驗…………………………………………30
4.4.2. 腔長優化之實驗結果與討論……………………………30
4.5. 晶體溫度與1064nm輸出功率之影響…………………………32
4.5.1. 簡介……………………………………………………..32
4.5.2. 1064nm輸出功率與晶體溫度變化之量測與討論………33
4.6. Nd:YVO4之1064nm雷射優化結果與討論…………………….34
4.7. 腔內損耗之量測………………………………………………36
4.7.1. Findlay腔內損耗計算法……………………………… 36
4.7.2. John-Caird腔內損耗計算………………………………37
4.7.3. 結論………………………………………………………38
5. 倍頻基本理論.…………………………………………………….40
5.1. 二次倍頻基本概念……………………………………………40
5.2. 二次諧波生成的理論…………………………………………40
5.3. 相位匹配………………………………………………………42
5.4. 高斯光束之二次諧波生成……………………………………43
5.5. 倍頻晶體之選取………………………………………………45
5.5.1. 晶體接受角對倍頻的影響………………………………46
5.5.2. Walkoff角度…………………………………………….46
5.6. 腔內倍頻………………………………………………………47
5.7. KTP(Potassium titanyl phosphate)晶體的特性…………48
5.8. 晶體切角之計算………………………………………………49
6. Nd:YVO4雷射腔內倍頻實驗…….…………………………………52
6.1. 簡介……………………………………………………………52
6.2. 模態匹配對倍頻之影響………………………………………52
6.3. KTP光軸角度與倍頻效率量測……………………………….54
6.4. KTP溫度與倍頻效率量測…………………………………….56
6.5. 倍頻實驗結果與討論…………………………………………58
7. 結論與未來研究展望………………………………………………59
7.1. 結論……………………………………………………………59
7.1.1. 實驗結果探討…………………………………………….59
7.1.2. 實驗缺失與改進………………………………………….61
7.2. 未來研究展望……………………………………………….62
參考文獻……………………………………………………………….63
自傳…………………………………………………………………….67

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