本論文為次兆瓦雷射尾流場電子加速系統中雷射系統之二級雷射放大器設計、架設與優化以及放大器後端脈衝壓縮器設計與架設。目標為將前級摻鐿鎢酸釓鉀再生放大器輸出之0.6 毫焦耳, 700皮秒雷射脈衝放大至數十毫焦耳。
系統包含將前級放大器輸出之雷射進行擴束與模態吻合進入摻鐿氟化鈣再生放大器進行放大並輸出至脈衝壓縮器壓縮。為優化放大器性能, 本篇論文對摻鐿氟化鈣晶體操作於不同溫度條件及冷卻方式之增益特性進行研究。 實驗上, 使用三種不同之冷卻器: 低溫冷卻器、致冷晶片以及浸入式冷卻器, 分別將摻鐿氟化鈣晶體冷卻至於
-160℃、17 ℃以及-84℃。由此三種不同的冷卻溫度與冷卻方式分析出摻鐿氟化鈣晶體在此放大需求下之最佳操作條件。脈衝壓縮器設計為將二級放大器輸出至700皮秒雷射脈衝壓縮至200飛秒, 並可承受最大110毫焦耳之脈衝能量。
實驗結果上, 測試三種不同冷卻方式之放大器, 使其皆可獲得放大增益, 並對放大器特性進行量測分析, 歸結出最適架設為使用浸入式冷卻器將摻鐿氟化鈣晶體冷卻至 -84℃, 使雷射可獲得單通增益1.11, 放大器可操作於1 Hz 至 25 Hz, 將雷射脈衝由0.6 毫焦耳放大至最高35 毫焦耳。 脈衝壓縮器使用測試光源可成功補償色散, 並壓縮至206 飛秒。

This thesis includes the design, the construction and the optimization of the second stage laser amplifier of the sub-terawatt laser wakefield acceleration system. The pulse compressor after the amplification were also designed and built.
The system consists the beam expansion, the mode matching, the regenerative amplifier and the pulse compressor. In order to optimize the performance of the Yb:CaF2 crystal, three different cooling temperatures and cooling methods were tested. The pulse compressor is designed to compensate the dispersion introduced by the pulse stretcher and the amplifier. The target is to compress the output pulse from 700 ps to 200 fs.
The experimental result shows that the Yb:CaF2 regenerative amplifier has the better performance when the crystal is cooled down to -84℃ by the immersion cooler. The amplifier can amplify the laser pulse from 0.6 mJ to 35 mJ at a 25 Hz repetition rate. The performance of the pulse compressor was verified with a testing laser source and successfully compensated the dispersion and compress the pulse duration to 206 fs.

1. Strickland, D. and G. Mourou, Compression of amplified chirped optical pulses. Optics Communications, 1985. 55(6): p. 447-449.
2. Goers, A.J., et al., Multi-MeV Electron Acceleration by Subterawatt Laser Pulses. Phys Rev Lett, 2015. 115(19): p. 194802.
3. Siebold, M., et al., Yb:CaF2--a new old laser crystal. Applied physics. B, Lasers and optics., 2009. 97(2): p. 327.
4. Fan, T.Y., Heat generation in Nd:YAG and Yb:YAG. IEEE J. Quantum Electron. IEEE Journal of Quantum Electronics, 1993. 29(6): p. 1457-1459.
5. Druon, F., et al., On Yb:CaF2 and Yb:SrF2 : Review of spectroscopic and thermal properties and their impact on femtosecond and high power laser performance. Opt. Mater. Express Optical Materials Express, 2011. 1(3): p. 489-502.
6. DeMaria, A.J., D.A. Stetser, and H. Heynau, self mode‐locking of lasers with saturable absorbers. Appl. Phys. Lett. Applied Physics Letters, 1966. 8(7): p. 174-176.
7. Fork, R.L., et al., Compression of optical pulses to six femtoseconds by using cubic phase compensation. Optics letters, 1987. 12(7): p. 483-5.
8. Shah, J. and T. Lucent, Ultrafast spectroscopy of semiconductors and semiconductor nanostructures. 2010, Berlin; New York: Springer Verlag.
9. Phillips, K.C., et al., Ultrafast laser processing of materials: a review. Adv. Opt. Photon. Advances in Optics and Photonics, 2015. 7(4): p. 684.
10. Treacy, E., Optical pulse compression with diffraction gratings. IEEE J. Quantum Electron. IEEE Journal of Quantum Electronics, 1969. 5(9): p. 454-458.
11. Papadopoulos, D.N., et al., High Repetition Rate Yb:CaF2 Multipass Amplifiers Operating in the 100-mJ Range. IEEE JOURNAL OF SELECTED TOPICS IN QUANTUM ELECTRONICS, 2015. 21(1): p. 1,11.
12. 黃志皓，「發展二極體汲發摻鐿氟化鈣再生放大器」，國立清華大學工程與系統科學所，碩士論文，中華民國一○八年
13. Martinez, O.E., J.P. Gordon, and R.L. Fork, Negative Group-Velocity Dispersion Using Refraction. Journal of the Optical Society of America a-Optics Image Science and Vision, 1984. 1(10): p. 1003-1006.
14. Backus, S., et al., High power ultrafast lasers. Review of Scientific Instruments, 1998. 69(3): p. 1207-1223.
15. Phillips, K.C., et al., Ultrafast laser processing of materials: A review. Adv. Opt. Photonics Advances in Optics and Photonics, 2015. 7(4): p. 684-712.