為了解決使用發光二極體(LED)作為泵浦光源時的問題，我們使用光導板以同時得到侷限泵浦光和隔離熱源兩種效果。第一個演示雷射中，LED被操作在準連續波(QCW)模式，重複週期和脈衝寬度分別為50赫茲和1毫秒，在最大泵浦能量為136.2毫焦耳時，我們自短共振腔的架構中得到了10.84毫焦耳的輸出能量，而最佳光轉光效率和斜率效率分別為8.0%和12.0%。在TEM00模態實驗中，增加腔長得到了能量集中的雷射，置入一限制模態的光圈後，完美地得到單一橫向模態，兩者的能量為8.04毫焦耳和5.88毫焦耳，和多模短共振腔雷射相比，能量為原本的74%和54%。此外，我們成功地將LED泵浦雷射操作在連續波(CW)模式，並在短和長共振腔的架構下得到370毫瓦和248毫瓦的輸出功率，最佳光轉光效率和斜率效率分別為2.6%和5.5%，在CW操作下，長共振腔架構可以直接得到單一橫向模態且不須放入限制模態的光圈。
第二個演示雷射中，搭配光導板的使用讓雷射裝置能夠裝載更多的泵浦LED，並產生高輸出的雷射，在QCW模式，350毫焦耳的泵浦能量下，短共振腔結構最高輸出為26毫焦耳，最佳光轉光效率和斜率效率分別為7.4%和12.0%。在TEM00模態實驗中，測得能量為2.6毫焦耳。在聲光Q開關雷射中，短和長共振腔結構分別得到6.6毫焦耳和760微焦耳的最大脈衝能量，而脈衝寬度為178奈秒，透過這些參數，可以推得4.2千瓦的峰值功率和9.7MW/cm2的峰值強度。

To increase the pump efficiency and improve thermal isolation in a LED-pumped laser, we use light guides to provide pump-guiding and thermal insulation. In the first demonstration, the LEDs are operated in a quasi-continuous-wave (QCW) mode with 50-Hz repetition rate and 1-ms pulse width. At the maximum pump energy of 136.2 mJ, we generate 10.84-mJ output energy at 1064 nm from a short Nd laser cavity with optical and slope efficiencies of 8.0 % and 12.0 %, respectively. In the experiment for demonstrating TEM00 lasing mode, the laser energy is more concentrating when the cavity length is increased. We generated a nearly perfect single laser mode by applying a mode-limited iris. We measure maximum output energies of 8.04 mJ and 5.88 mJ without and with an iris in the long-cavity laser, respectively. The output energy of long-cavity laser reduces to 74 % and 54 % with and without the iris, respectively, compared with the maximum output energy from short-cavity multi-mode laser. Most importantly, we successfully operate the LED-pump laser in CW mode. The maximum laser powers of short and long cavity were measured to be 370 and 248 mW, respectively. The corresponding optical and slope efficiencies are 2.6 % and 5.5 %, respectively. For the CW laser, a single transverse laser mode is achieved without adding a mode-limiting iris.
In the second demonstration, the new design was aimed to assemble more pumping LEDs by using light guides, permitting generation of high laser power at the output. Operated at QCW mode, the laser generates a maximum output energy of 26 mJ at the maximum pump energy of 350 mJ from the short-cavity design. The corresponding optical and slope efficiencies are 7.4 % and 12 %, respectively. With a TEM00 lasing mode, the maximum output energy is 2.6 mJ, which is about 10 % of that from a short-cavity laser. Finally, we report an acousto-optically Q-switched LED-pumped Nd laser. The maximum output energy of the short and long cavity lasers are 6.6 mJ and 760μJ, respectively, in a pulse width of 178 ns. The corresponding peak power and intensities are 4.2 kW and 9.7 MW/cm2, respectively.

Abstract i
中文摘要 ii
Acknowledgment iii
Table of Contents iv
List of Tables vi
List of Figures vii
Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Review of solid-state laser 2
1.3 Nd:YAG gain medium 3
1.4 LED-pumped chamber 6
Chapter 2 Theorem and analysis 9
2.1 Pumping optical design 9
2.1.1 Coupling efficiency 10
2.1.2 Heat simulation 14
2.1.3 Comparison 16
2.2 Laser theorem 17
2.2.1 Rate equation of four-level system 17
2.2.2 Laser oscillation 19
2.2.3 Resonators design 20
2.3 Acoustic-optical Q-switch 22
2.3.1 Principle 22
2.3.2 Theoretic model 24
Chapter 3 Optical design for LED-pumped Nd:YAG laser 26
3.1 Experiment setup 27
3.2 Quasi-continuous wave operation 29
3.3 Continue wave operation 33
3.4 Results and discussion 35
Chapter 4 LED-pumped Nd:YAG-rod laser with Q-switch 36
4.1 Experiment setup 37
4.2 Quasi-continue wave operation 39
4.3 AO Q-switched laser 41
4.4 Results and discussion 43
Chapter 5 Conclusions and future work 45
5.1 Conclusions 45
5.2 Future works 47
Reference 48

[1]. Steele, R. V. (2007). The story of a new light source. Nature photonics, 1(1), 25-26
[2]. K. Y. Huang, C. K. Su, M. W. Lin, Y. C. Chiu, and Y. C. Huang (2016). Efficient 750-nm LED-pumped Nd:YAG laser. Optics Express, 24(11), 12043-12054
[3]. C. Y. Cho, C. C. Pu, K. W. Su, and Y. F. Chen (2017). LED-side-pumped Nd:YAG laser with >20% optical efficiency and the demonstration of an efficient passively Q-switched LED-pumped solid-state laser. Optics Letters, 42(12), 2394-2397
[4]. A. L. Schawlow and C. H. Townes (1958). Infrared and optical masers. Physical Review, 112(6), 1940-1949
[5]. T. H. Maiman (1960). Stimulated optical radiation in ruby. Nature, 187(4736), 493-494
[6]. Moulton, P. F. (1986). Spectroscopic and laser characteristic of Ti:Al2O3. JOSA B, 3(1), 125-133
[7]. W. Shi and Y. J. Ding (2002). Efficient, tunable, and coherent 0.18–5.27-THz source based on GaSe crystal. Optics Letters, 27(16), 1454-1456
[8]. A. Rundquist, C. G. Durfee III, Z. Chang, C. Herne, S. Backus, M. M. Murnane, H. C. Kapteyn (1998). Phase-Matched Generation of Coherent Soft X-rays. Science 280(5368), 1412-1415
[9]. W. Koechner (2006). Solid-State Laser Engineering (6th ed). Round Hill, VA: Springer
[10]. B. E. A. Saleh and M. C. Teich (2007). Fundamentals of Photonics (2nd ed). Hoboken, New Jersey: Wiley