姓名 |
劉士誠(Shih-cheng Liu)
查詢紙本館藏 |
畢業系所 |
物理學系 |
論文名稱 |
利用不同波長脈衝雷射產生高階諧波並最佳化相位匹配條件 (Optimization of the High Harmonic Generation Phase-Matching Condition with Different Pump Wavelengths)
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相關論文 | |
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摘要(中) |
高階諧波產生是一種高相干性Extreme-UV/X-ray光源,過去三年來,我們的實驗團隊一直在努力提升高階諧波的輸出效率與能量,在我接手之前,利用810-nm雷射脈衝入射Ar氣體,所產生高階諧波的第23階脈衝輸出能量可達到1.2 nJ,轉換效率為1.6×〖10〗^(-7)。由於在相位匹配條件下,使用較短波長的激發光源可以有效提升高階諧波產生的轉換效率,因此,在本論文中,我使用由810 nm二倍頻至405 nm的超短脈衝,做為高階諧波的激發光源,實驗結果顯示此方法成果顯著,在40-nm波段附近,405-nm激發光源的第9階高階諧波輸出能量提升至280.6 nJ,轉換效率達到 2.3×〖10〗^(-5)。
本論文紀錄我提升高階諧波輸出效率的方法,並比較使用不同激發光源波長、與使用不同氣體所產生高階諧波的差異,得到與理論預期相符的結果。其次,為了得到高階諧波的絕對輸出能量,我量測了高階諧波對鋁箔膜的穿透率,結果顯示,鋁箔膜對35-nm與45-nm 高階諧波的穿透率分別為13.9 % 與 4.0 %,這讓我們得以計算高階諧波的絕對輸出能量與絕對轉換效率。最後,我觀測激發雷射脈衝穿過交互作用氣體時的Thomson Scattering,測得高階諧波產生過程中,自由電子的相對密度,驗證了不同波長產生高階諧波的相位匹配條件。 |
摘要(英) |
High-order harmonic generation (HHG) is a kind of ultrashort coherent EUV/x-ray source. In this thesis, I report the frequency-doubling of 810-nm ultrashort laser pulses, and then use these 405-nm pulses to drive HHG. Comparing with the HHG yield driven by 810-nm pulses, the conversion efficiency is significantly increased with 405-nm pumping. The output pulse energy of the 9th harmonic (about 45-nm wavelength) from Ar gas reaches 280.6 nJ, corresponds to a conversion efficiency of about 2.3 × 10−5.
In the experiment, the HHG output is filtered by aluminum filters to block the driving pulse. In order to obtain the absolute HHG yield, I design an aluminum filter pair to calibrate the filter transmittance. The results show that the transmittances for 35-nm and 45-nm HHGs are 13.9% and 4.0%, respectively. These values are essential for the calculation of HHG pulse energy. Furthermore, I measured the Thomson scatterings from the interacting medium with different pump wavelengths. Comparing these Thomson scattering intensities, the relative electron densities and the ionization ratios are obtained. The results consist with the theoretical calculation of the phase-matching conditions with different pumping wavelengths. |
關鍵字(中) |
★ 高階諧波 ★ 相位匹配條件 |
關鍵字(英) |
★ High Harmonic Generation ★ Phase-matching condition |
論文目次 |
誌謝 i
中文摘要 iii
Abstract iv
目錄 v
圖目錄 viii
表目錄 xi
Chapter 1 High Harmonic Generation 1
1.1 引言 1
1.2 高階諧波產生原理 2
1.3 三步驟模型 - Three-step model 3
1.4 高階諧波的相位匹配 7
1.4.1 Neutral gas dispersion 8
1.4.2 Plasma dispersion 9
1.4.3 Geometrical phase shift 10
1.5 高階諧波的轉換效率 11
Chapter 2 Second Harmonic Generation (SHG) 12
2.1 倍頻晶體的選擇 12
2.1.1 BBO or KDP 12
2.1.2 尋常光 (Ordinary wave) 與非尋常光 (Extraordinary wave) 13
2.1.3 Type I or Type II 14
2.1.4 相位匹配角度 Type I (Phase Matching Angle) 15
2.2 SHG規格 17
2.2.1 架設KDP晶體 17
2.2.2 SHG光譜 18
2.2.3 SHG效率 19
Chapter 3 HHG實驗架設與參數 21
3.1 雷射系統參數 21
3.1.1 雷射脈衝時寬 21
3.1.2 雷射脈衝時間對比度 22
3.2 實驗區參數與架設 23
3.2.1 實驗架設 24
3.2.2 聚焦大小 (Focal spot size) 24
3.2.3 空間穩定性 (Pointing stability) 26
3.2.4 相位匹配條件 27
3.2.5 側向散射成像系統 (Side scattering imaging system) 28
3.2.6 傳繼成像系統 (Relayed-imaging system) 29
3.2.7 EUV 光譜儀 (EUV spectrometer) 30
Chapter 4 實驗結果 31
4.1 HHG光譜 31
4.2 相位匹配條件 – 改變氣體密度 34
4.3 相位匹配條件 – 改變雷射強度 37
4.4 高階諧波輸出規格 40
4.5 鋁箔膜 (Al filter) 穿透率 42
4.6 計算高階諧波輸出效率 45
4.7 電子密度與游離比例 46
4.8 氦氣產生高階諧波光譜 48
Chapter 5 總結 49
參考文獻 50
附錄一 51
附錄二 52
附錄三 57
附錄四 62
附錄五 66 |
參考文獻 |
[1] Second generation high order harmonic generation Piotr_Rudawski_PhD_Thesis
[2] C. G. Durfee, A. R. Rundquist, S. Backus, C. Herne, M. M. Murnane, and H. C. Kapteyn, “Phase Matching of High-Order Harmonics in Hollow Waveguides,” Phys. Rev. Lett., vol. 83, no. 11, pp. 2187–2190, Sep. 1999.
[3] Kapteyn-Murnane Laboratories website:http://www.kmlabs.com/content/high-harmonic-generation
[4] Single-Shot Intensity Waveform Measurement of Ultrashort Extreme-UV Pulses Chi-Hsiang Yang_PhD _Thesis
[5] 2008-RMP-Colloquium Optimal control of high-harmonic generation
[6] Corkum P B 1993 Phys. Rev. Lett. 71 1994
[7] Kulander K C, Schafer K J and Krause J L 1993 Proc. Work-shop on Super-Intense Laser Atom Physics (SILAP) III ed B Piraux (New York: Plenum) pp 95–110
[8] 2006-RPP-Femtosecond x-ray science
[9] 1998-PRL-Temporal Coherence of Ultrashort High-Order Harmonic Pulses
[10] Phase-matched high-harmonic generation in extreme ultraviolet range Hao_Chen_MS_Thesis
[11] 2013-CLEO-QW1A-5-Ultrahigh-Efficiency High Harmonic Generation Driven by UV Lasers
[12] Eksma website: http://eksmaoptics.com/nonlinear-and-laser-crystals/nonlinear-crystals/ultrathin -crystals-for-femtosecond-applications/
[13] Principles of Nonlinear Optics Course Reader P.187_Yen-Chieh Huang
[14] Photonic_Optical Electronics in Modern Communications_P365
[15] Sellmeier Equations of KDP: http://www.newlightphotonics.com/index.php?route=product/category&path=104_237
[16] Group velocity dispersion:http://refractiveindex.info/?shelf=other&book=air&page=Ciddor
[17] Development of a flat-field grazing-incidence spectrometer and its application in the
characterization of XUV laser-plasma emission_M.-Y. Shen
[18] Filter transmission:http://henke.lbl.gov/optical_constants/filter2.html
[19] Thomson Scattering:http://www-ppl.s.chiba-u.jp/lecture/radiation/node1.html |
指導教授 |
朱旭新(Hsu-hsin Chu)
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審核日期 |
2015-11-30 |
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