微弱光脉冲多程放大技术研究
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摘要
泵浦源技术是光参量啁啾脉冲放大技术的关键技术之一。为开展泵浦源技术的研究,本论文对弱信号的高增益放大技术进行了初步研究。利用多程放大技术实现了对脉宽5ns、能量仅为0.2nJ的微弱信号的放大。同时,对高增益放大过程中的增益、波形失真以及光路调节等问题进行了分析和讨论。
本文首先介绍了泵浦源前端的设计,分析了Nd:YAG增益介质的特性,利用激光放大的模型对多程放大进行了数值模拟,分析了脉冲放大过程中的波形失真现象,提出了为实现窄脉冲平顶的泵浦激光所需的泵浦源前端注入脉冲波形情况。
其次,为实现从光纤脉冲源到固体放大器的有效耦合,分析了多程放大的光学设计以及光路调整问题,针对光路调整提出了比较实用的原则。按照所提出的方法,可以精确的实现多程放大器的光路调整。
最后,对微弱信号进行了多程放大实验,分别利用双程、四程和六程放大,实现了对脉冲宽度为5ns、10ns、20ns、50ns、100ns的激光放大,分析了冷却温度、泵浦电压对放大效果的影响,对放大过程中的弛豫振荡和寄生振荡对输出波形的影响进行了分析。为实现波形保真的脉冲放大,应使放大系统工作在线性区。
本文还对脉冲放大过程中的波形失真现象进行了研究,发现对不同脉冲宽度的弱信号脉冲,波形畸变情况有所不同,50ns脉冲的波形畸变较小。为实现对数ns脉冲的波形保真放大,应该减少系统当中的寄生振荡。通过在光路中增加小孔滤波来抑制寄生振荡,使波形畸变得到控制,取得了良好的效果。
通过对多程放大过程中遇到的困难和现象进行分析,认为通过提高注入信号能量可以取得更好的效果;在不能增加注入能量的情况下,应选择再生放大技术来实现高增益放大,由于再生放大中脉冲在腔内往返次数更多,对元件的质量、抑制自激和寄生振荡技术提出了更高的要求。
Pump laser is a key issue in optical parametric chirped pulse amplification technology. In order to develop a pump laser, the high gain amplified technology of weak signal is investigated. A weak pulse of 5ns, 0.2nJ is amplified by multi-pass technology. In the mean time, system gain and pulse distortion in the process of amplification is discussed. The adjustment technology of the optical path is also discussed.
At first, the thesis introduced the design of the front-end of a pump laser, analyzed the physical and optical feature of the gain material Nd:YAG, simulated the process of multi-pass amplification based on the model of laser amplification, analyzed the pulse distortion in the process of pulse amplification, advanced the pulse shape of the front-end pump source for realizing flat-top pump laser.
Secondly, in order to realized efficient coupling from laser fiber pulse source to solid state amplifier, the optical design of multiple pass amplification is analyzed and the adjustment on optical system, practical principles on adjustment is advanced. Following the provided method, the accurate adjustment of multi-pass amplifier should be realized.
In the end, the multi-pass amplification of weak signal is investigated in the way of double-pass, four-pass and six-pass amplification, and realized the laser amplification of signals which pulse width varied from 5ns, 10ns,20ns, 50ns and 100ns, the influence of cooling system and pump energy is analyzed, and relaxation oscillation and parasitic modes was observed in the process of amplification. It is found that in order to realized the pulse amplification without pulse distortion, the amplification system should work in the region of linearity amplification.
Signals with different pulse width have different pulse distortion, for example, pulse distortion of 50ns pulse is small. Therefore, in order to realize the amplification on ns-level signal, parasitic mode should be decreased. By adding a pinhole in the light path, pulse distortion is restrained. And better result should be expected by spatial filter and further more methods.
Through analyzing the confronted problems and puzzles, we assume that enhancing the power of injecting signal will obtain better experimental result; with limited condition of signal power, regenerative amplification technology should be adopted to realize high gain amplification. However, the principle of regenerative amplification requires input signal to go backward and forward many times inside the cavity, better quality of optical devices, controlling ASE and preventing parasitic modes should be considered.
本文首先介绍了泵浦源前端的设计,分析了Nd:YAG增益介质的特性,利用激光放大的模型对多程放大进行了数值模拟,分析了脉冲放大过程中的波形失真现象,提出了为实现窄脉冲平顶的泵浦激光所需的泵浦源前端注入脉冲波形情况。
其次,为实现从光纤脉冲源到固体放大器的有效耦合,分析了多程放大的光学设计以及光路调整问题,针对光路调整提出了比较实用的原则。按照所提出的方法,可以精确的实现多程放大器的光路调整。
最后,对微弱信号进行了多程放大实验,分别利用双程、四程和六程放大,实现了对脉冲宽度为5ns、10ns、20ns、50ns、100ns的激光放大,分析了冷却温度、泵浦电压对放大效果的影响,对放大过程中的弛豫振荡和寄生振荡对输出波形的影响进行了分析。为实现波形保真的脉冲放大,应使放大系统工作在线性区。
本文还对脉冲放大过程中的波形失真现象进行了研究,发现对不同脉冲宽度的弱信号脉冲,波形畸变情况有所不同,50ns脉冲的波形畸变较小。为实现对数ns脉冲的波形保真放大,应该减少系统当中的寄生振荡。通过在光路中增加小孔滤波来抑制寄生振荡,使波形畸变得到控制,取得了良好的效果。
通过对多程放大过程中遇到的困难和现象进行分析,认为通过提高注入信号能量可以取得更好的效果;在不能增加注入能量的情况下,应选择再生放大技术来实现高增益放大,由于再生放大中脉冲在腔内往返次数更多,对元件的质量、抑制自激和寄生振荡技术提出了更高的要求。
Pump laser is a key issue in optical parametric chirped pulse amplification technology. In order to develop a pump laser, the high gain amplified technology of weak signal is investigated. A weak pulse of 5ns, 0.2nJ is amplified by multi-pass technology. In the mean time, system gain and pulse distortion in the process of amplification is discussed. The adjustment technology of the optical path is also discussed.
At first, the thesis introduced the design of the front-end of a pump laser, analyzed the physical and optical feature of the gain material Nd:YAG, simulated the process of multi-pass amplification based on the model of laser amplification, analyzed the pulse distortion in the process of pulse amplification, advanced the pulse shape of the front-end pump source for realizing flat-top pump laser.
Secondly, in order to realized efficient coupling from laser fiber pulse source to solid state amplifier, the optical design of multiple pass amplification is analyzed and the adjustment on optical system, practical principles on adjustment is advanced. Following the provided method, the accurate adjustment of multi-pass amplifier should be realized.
In the end, the multi-pass amplification of weak signal is investigated in the way of double-pass, four-pass and six-pass amplification, and realized the laser amplification of signals which pulse width varied from 5ns, 10ns,20ns, 50ns and 100ns, the influence of cooling system and pump energy is analyzed, and relaxation oscillation and parasitic modes was observed in the process of amplification. It is found that in order to realized the pulse amplification without pulse distortion, the amplification system should work in the region of linearity amplification.
Signals with different pulse width have different pulse distortion, for example, pulse distortion of 50ns pulse is small. Therefore, in order to realize the amplification on ns-level signal, parasitic mode should be decreased. By adding a pinhole in the light path, pulse distortion is restrained. And better result should be expected by spatial filter and further more methods.
Through analyzing the confronted problems and puzzles, we assume that enhancing the power of injecting signal will obtain better experimental result; with limited condition of signal power, regenerative amplification technology should be adopted to realize high gain amplification. However, the principle of regenerative amplification requires input signal to go backward and forward many times inside the cavity, better quality of optical devices, controlling ASE and preventing parasitic modes should be considered.
引文
1 T.H.Maiman. Stimulated Optical Radiation in Ruby. Nature, 1960, 187(4736): 493~494
2 R. Collins, P. Kisliuk. J. Control of Population Inversion in Pulsed Optical Masers by Feedback Modulation . Appl. Phys. 1962,33:2009
3 H. Mocker, R. Collins. Mode competition and self-locking effects in a Q-switched ruby laser. Appl. Phys. Lett. 1965,7: 270
4 D. Strickland, G. Mourou. Compression of amplified chirped optical pulses. Optics Communications. 1985,56(3):219~221
5 M. D. Perry, D. Pennington, B.C. Stuart, et al. Petawatt laser pulses. Opt. Lett.,1999,22:160~162
6 N. Ross, J. L. Collier, P. Matousek, et al. Generation of terawatt pulses use of optical parametric chirped pulse amlification. Appl. Opt., 2000, 39(15): 2422~2426
7 Pavel Matousek, Bedrich Rus, and Ian N. Ross. Design of a Multi-Petawatt Optical Parametric Chirped Pulse Amplifier for the Iodine Laser ASTERIX IV. IEEE J. QE. 2000, 36(2):158
8 E. Hugonnot, J. Luce et al. Optical parametric chirped-pulse amplifier and spatiotemporal shaping for a petawatt laser. Applied Optics. 2006,45(2): 377~382
9 M. Aoyama, K. Yamakawa, Y. Akahane, et al. 0.85-PW,33-fs Ti:sapphire laser. Opt. Lett., 2003, 28: 1594 ~ 1596
10彭翰生.超强固体激光及其在前沿学科中的应用.中国激光. 2006, 33(7): 865~872
11 Richard A. Baumgartner, Robert L.Byer. Optical parametric amplification. IEEE Journal of Quantum Electronics.1979,15(6):432~444
12 A. Dubietis, G. Jonusauskas, A. Piskarskas. Powerful femtosecond pulse generation by chirped and stretched pulse parametric amplification in BBO crystal. Optics Communications. 1992,88:437~440
13 I.N.Ross, P Matousek, M.Towrie,et al., The prospects for ultrashort pulse duration and ultrahigh intensity using optical parametric chirped pulse amplification. Opt. Commun.,1997,144:125~133
14 I.N. Ross, P. Matousek et al. Analysis and optimization of optical parametric chirped pulse amplification. J.Opt.Soc. Am. B. 2002, 19(12): 2945~2956
15 S. K. Zhang, M. Fujita et al. Study of the stability of optical parametricamplification. Optics Communications. 2000,184: 451~455
16 X. Wei, L. Qian, P. Yuan, et al. Optical parametric amplification pumped by a phase-aberrated beam. Optics Express. 2008,16(12): 8904
17 Igor Jovanovic, Brian J. Comaskey Optical parametric chirped-pulse amplifier as an alternative to Ti:sapphire regenerative amplifiers. Applied Optics. 2002, 41(15): 2923~2929
18 L. J. Waxer, V. Bagnoud, I. A. Begishev, et al. High-conversion-efficiency optical parametric chirped-pulse amplification system using spatiotemporally shaped pump pulses. Optics Letters. 2003, 28(14): 1245~1247
19 M. D. Skeldon. A high-bandwidth electrical waveform generator based on an aperture-coupled stripline. Rev. Sci. Instrum. 71, 3559(2000)
20 N. Blanchot, E.Bignon et al. Multi-Petewatt high energy laser project on the LIL faclility in Aquitaine. SPIE. 2006, 5975: 59750C-1~16
21 E. Hugonnot, J. Luce et al. Optical parametric chirped-pulse amplifier and spatiotemporal shaping for a petawatt laser. Applied Optics. 2006, 45(2): 377~382
22 X. Yang, Z. Xu, Y. Leng, et al. Multiterawatt laser system based on optical parametric chirped pulse amplification. Optics Letters. 2002,27(13):1135~1137
23 Z. Z. Xu , X. D. Yang , Y. X. Leng et al . High power output from a compact OPCPA laser system [J] . Chin. Opt . Lett . ,2003 , 1 (1) : 24～27
24 W. Lowdermilk, J. Murray. The multipass amplifier: Theory and numerical analysis. J. Appl. Phys., 1980, 51(5): 2436~2444
25 J. Murray, W. Lowdermilk. Nd: YAG regenerative amplifier. J. Appl. Phys., 1980, 51(7): 3548~3555
26 M. Saeed, D. Kim, L. DiMauro. Optimization and characterization of a high repetition rate, high intensity Nd:YLF regenerative amplifier. Applied Optics. 1990, 29(12): 1752~1757
27 Y. Leng, L Lin, X. Yang, et al. Regenerative amplifier with continuously variable pulse duration used in an optical parametric chirped-pulse amplification laser system for synchronous pumping. Opt. Eng., 2003, 42(3): 862~866
28 Heller A , Walter K, Wilt G1 Leading the best and the brightest. Science & Technology Review , 1999, (1): 4~11
29 Heller A. Collaboration ignites laser advances [J] . Science & Technology Review, 1999, (6): 19~21
30 Yamanaka C 1 Introduction to laser fusion [M] .Switzerland , Harwood Academic Publisher , 1990
31 Kirillov G A1 Development of a high2power 300 kJ neodimium laser [A] . Solid2state Lasers for Application to ICF, Oct 1996: 43~47
32 Peter J. Wisoff, Mark W. Bowers, Gaylen V. Erbert, et al. NIF Injection Laser System. Proc. of SPIE. 2004, 5341: 146~155
33 S. C. Burkhart et al., in First Annual International Conference on Solid State Lasers for Application to Inertial Confinement Fusion, edited by M. Andréand H. T. Powell (SPIE, Bellingham, WA, 1995), 2633:48~58.
34 Audrey V. Okishev, Devon J. Battaglia, Ildar A. Begishev, et al. Highly stable, diode-pumped, cavity-dumped Nd:YLF regenerative amplifier for the OMEGA laser fusion facility. OSA TOPS. 2002, 68: 418~422
35沈小华,陈绍和等.单纵模激光的再生放大.中国激光. 1995, 22(11):818
36韦辉,张生佳等. LDA抽运的Nd: YLF再生放大器的实验研究.中国激光. 2003, 30(8): 677~680
37王之桐,陈三斌.激光二极管侧抽运Nd: YLF多程放大实验研究.中国激光. 2005, 32(5): 590~593
38邓明发,秘国江等.二极管泵浦再生放大器技术研究.激光与红外. 2009, 39(2): 151~154
39王春,陈绍和等. ICF固体激光驱动器前级系统中的脉冲整形.量子电子学报. 2000, 17(6): 479~492
40 W. Koechner. Solid-State Laser Engineering. Springer-Verlag. 1999:40~42
41王芳,朱启华等.多程放大主系统放大级光学优化设计.物理学报. 2006, 55(10): 5278~5282
2 R. Collins, P. Kisliuk. J. Control of Population Inversion in Pulsed Optical Masers by Feedback Modulation . Appl. Phys. 1962,33:2009
3 H. Mocker, R. Collins. Mode competition and self-locking effects in a Q-switched ruby laser. Appl. Phys. Lett. 1965,7: 270
4 D. Strickland, G. Mourou. Compression of amplified chirped optical pulses. Optics Communications. 1985,56(3):219~221
5 M. D. Perry, D. Pennington, B.C. Stuart, et al. Petawatt laser pulses. Opt. Lett.,1999,22:160~162
6 N. Ross, J. L. Collier, P. Matousek, et al. Generation of terawatt pulses use of optical parametric chirped pulse amlification. Appl. Opt., 2000, 39(15): 2422~2426
7 Pavel Matousek, Bedrich Rus, and Ian N. Ross. Design of a Multi-Petawatt Optical Parametric Chirped Pulse Amplifier for the Iodine Laser ASTERIX IV. IEEE J. QE. 2000, 36(2):158
8 E. Hugonnot, J. Luce et al. Optical parametric chirped-pulse amplifier and spatiotemporal shaping for a petawatt laser. Applied Optics. 2006,45(2): 377~382
9 M. Aoyama, K. Yamakawa, Y. Akahane, et al. 0.85-PW,33-fs Ti:sapphire laser. Opt. Lett., 2003, 28: 1594 ~ 1596
10彭翰生.超强固体激光及其在前沿学科中的应用.中国激光. 2006, 33(7): 865~872
11 Richard A. Baumgartner, Robert L.Byer. Optical parametric amplification. IEEE Journal of Quantum Electronics.1979,15(6):432~444
12 A. Dubietis, G. Jonusauskas, A. Piskarskas. Powerful femtosecond pulse generation by chirped and stretched pulse parametric amplification in BBO crystal. Optics Communications. 1992,88:437~440
13 I.N.Ross, P Matousek, M.Towrie,et al., The prospects for ultrashort pulse duration and ultrahigh intensity using optical parametric chirped pulse amplification. Opt. Commun.,1997,144:125~133
14 I.N. Ross, P. Matousek et al. Analysis and optimization of optical parametric chirped pulse amplification. J.Opt.Soc. Am. B. 2002, 19(12): 2945~2956
15 S. K. Zhang, M. Fujita et al. Study of the stability of optical parametricamplification. Optics Communications. 2000,184: 451~455
16 X. Wei, L. Qian, P. Yuan, et al. Optical parametric amplification pumped by a phase-aberrated beam. Optics Express. 2008,16(12): 8904
17 Igor Jovanovic, Brian J. Comaskey Optical parametric chirped-pulse amplifier as an alternative to Ti:sapphire regenerative amplifiers. Applied Optics. 2002, 41(15): 2923~2929
18 L. J. Waxer, V. Bagnoud, I. A. Begishev, et al. High-conversion-efficiency optical parametric chirped-pulse amplification system using spatiotemporally shaped pump pulses. Optics Letters. 2003, 28(14): 1245~1247
19 M. D. Skeldon. A high-bandwidth electrical waveform generator based on an aperture-coupled stripline. Rev. Sci. Instrum. 71, 3559(2000)
20 N. Blanchot, E.Bignon et al. Multi-Petewatt high energy laser project on the LIL faclility in Aquitaine. SPIE. 2006, 5975: 59750C-1~16
21 E. Hugonnot, J. Luce et al. Optical parametric chirped-pulse amplifier and spatiotemporal shaping for a petawatt laser. Applied Optics. 2006, 45(2): 377~382
22 X. Yang, Z. Xu, Y. Leng, et al. Multiterawatt laser system based on optical parametric chirped pulse amplification. Optics Letters. 2002,27(13):1135~1137
23 Z. Z. Xu , X. D. Yang , Y. X. Leng et al . High power output from a compact OPCPA laser system [J] . Chin. Opt . Lett . ,2003 , 1 (1) : 24～27
24 W. Lowdermilk, J. Murray. The multipass amplifier: Theory and numerical analysis. J. Appl. Phys., 1980, 51(5): 2436~2444
25 J. Murray, W. Lowdermilk. Nd: YAG regenerative amplifier. J. Appl. Phys., 1980, 51(7): 3548~3555
26 M. Saeed, D. Kim, L. DiMauro. Optimization and characterization of a high repetition rate, high intensity Nd:YLF regenerative amplifier. Applied Optics. 1990, 29(12): 1752~1757
27 Y. Leng, L Lin, X. Yang, et al. Regenerative amplifier with continuously variable pulse duration used in an optical parametric chirped-pulse amplification laser system for synchronous pumping. Opt. Eng., 2003, 42(3): 862~866
28 Heller A , Walter K, Wilt G1 Leading the best and the brightest. Science & Technology Review , 1999, (1): 4~11
29 Heller A. Collaboration ignites laser advances [J] . Science & Technology Review, 1999, (6): 19~21
30 Yamanaka C 1 Introduction to laser fusion [M] .Switzerland , Harwood Academic Publisher , 1990
31 Kirillov G A1 Development of a high2power 300 kJ neodimium laser [A] . Solid2state Lasers for Application to ICF, Oct 1996: 43~47
32 Peter J. Wisoff, Mark W. Bowers, Gaylen V. Erbert, et al. NIF Injection Laser System. Proc. of SPIE. 2004, 5341: 146~155
33 S. C. Burkhart et al., in First Annual International Conference on Solid State Lasers for Application to Inertial Confinement Fusion, edited by M. Andréand H. T. Powell (SPIE, Bellingham, WA, 1995), 2633:48~58.
34 Audrey V. Okishev, Devon J. Battaglia, Ildar A. Begishev, et al. Highly stable, diode-pumped, cavity-dumped Nd:YLF regenerative amplifier for the OMEGA laser fusion facility. OSA TOPS. 2002, 68: 418~422
35沈小华,陈绍和等.单纵模激光的再生放大.中国激光. 1995, 22(11):818
36韦辉,张生佳等. LDA抽运的Nd: YLF再生放大器的实验研究.中国激光. 2003, 30(8): 677~680
37王之桐,陈三斌.激光二极管侧抽运Nd: YLF多程放大实验研究.中国激光. 2005, 32(5): 590~593
38邓明发,秘国江等.二极管泵浦再生放大器技术研究.激光与红外. 2009, 39(2): 151~154
39王春,陈绍和等. ICF固体激光驱动器前级系统中的脉冲整形.量子电子学报. 2000, 17(6): 479~492
40 W. Koechner. Solid-State Laser Engineering. Springer-Verlag. 1999:40~42
41王芳,朱启华等.多程放大主系统放大级光学优化设计.物理学报. 2006, 55(10): 5278~5282