LD端泵Nd：GdVO_4激光器散热技术研究
摘要
激光晶体泵浦波长转移过程中,部分泵浦功率不可避免地要转化成热功率,导致晶体内部温度的空间分布不均匀,从而引起热致形变,热应力和热致双折射等热效应。随着固体激光器技术的飞速发展,激光晶体的热效应已成为影响激光大功率化、调Q以及倍频的瓶颈问题,因此,本论文主要论述了如何解决晶体的散热问题。
本文从晶体的内部温度分布推导开始,计算了晶体热透镜焦距,对比了Nd:GdVO4, Nd:YVO4, Nd:YAG三种晶体的热负载比,分析了晶体内部热应力分布,并用LASCAD软件模拟了晶体内部热梯度及应力分布,为我们的散热提供了理论依据。随后,我们又从热传导及流体力学的基本理论出发,重点论述了微通道及铟封的散热原理,为我们下面的实验进行奠定了基础。通过实验我们对比了传统的直通孔式循环水制冷热沉、微通道铟包循环水制冷热沉以及结合了铟封技术的微通道循环水制冷热沉三种散热装置的散热效果,说明了我们采取新型散热装置的良好效果。
实验中,我们采用LD端泵Nd:GdVO4晶棒,平-平腔结构。在泵浦功率为28W的时候,采用传统通孔热沉和微通道热沉分别获得8.66W和10.5W的最大输出功率,光-光效率分别为31%和36%,斜效率分别为38%和42%,另外我们采用微通道热沉并结合铟封技术,在泵浦功率为40W的时候获得最大功率17.5W,且还没有达到输出饱和状态,功率仍呈线性增长,光-光效率和斜效率分别为44%和49%。比较三组数据,我们得出采用铟封微通道热沉的散热效果是明显的。
我们还测得同样的热透镜焦距(350mm)下,采用铟包微通道热沉,晶体吸收的泵浦功率为6.5W,而采用铟封技术的微通道热沉则可以吸收39.5W,这也说明我们采用铟封技术的微通道散热装置对晶体热焦距改善是很明显的。最值得一提的是,我们用光束轮廓分析仪测得了他们的光强分布情况,在传统的通孔式热沉下我们最多只能得到4W的基模输出,采用微通道热沉则可以得到8W的基模输出,而采用微通道结合铟封技术的热沉我们至少可以得到13W基模的高水平,这一基模激光功率的提高,对我们进行连续端泵DPSL调Q、倍频等的研究价值是很可观的。
In the process of pump wavelength transferring, part of the pump power transforms into thermal power inevitably, which will lead to the uneven spatial distribution of temperature inside the crystal, so it will arouse the thermal deformation, thermal stress and birefraction. Thermal effect of laser crystal has already become the bottleneck problem in the power scaling, Q-switch operation and frequency doubling with the rapid development of solid-state laser technology. So we discuss how to solve the thermal dissipation problem in the thesis.
In the paper, modeling of temperature and thermal stress distribution in the crystal, calculation of focal length of thermal-lens and the heat load comparison among Nd:GdVO4, Nd:YVO4 and Nd:YAG were made theoretically. Meanwhile, the temperature field and thermal stress distribution in the crystal were simulated by LASCAD software. All of these provide theoretical basis for our elimination of heat. Then based on the principle of thermal conductivity and fluid mechanics, radiating mechanism of the microchannel heat-sink and the indium solder are discussed, which provides basis for the following experiment.
In the experiment, by comparing the experimental results of the three different kinds of heat-sink, i.e., traditional common heat-sink, indium-wrapped microchannel heat-sink and, indium solder microchannel heat-sink, we demonstrate the good performance of our novel-designed equipment.
In the experiment, we used LD end-pumped Nd:GdVO4 scheme and plano-plano cavity was employed. Under 28W pump power, we obtained 8.66W(in traditional common heat-sink) and 10.5W(in indium-wrapped microchannel heat-sink) output respectively. The optical-optical efficiency is 31% and 36%, slope efficiency is 38% and 42%, correspondingly. But when adding indium-soldered technique to microchannel heat-sink, 17.5W output was obtained under 40W incident pump power, corresponding to the optical-optical efficiency of 44% and slope efficiency of 49%. What’s more, the laser output has not been saturated. Comparing the three groups of data, we can see the effect of indium-soldered microchannel heat-sink is evident.
We also measured the absorbed pump power under the same thermal lens (f=350mm). When using the indium-wrapped heat-sink, the crystal can absorb 6.5W pump power; but for the indium-soldered heat-sink, the crystal can absorb 39.5W pump power, which can also demonstrate superiority of the new technique in thermal dissipation.
Especially, we measured the spatial distribution of transversal mode by the laser beam analyzer. 4W and 8W fundamental mode was obtained in common heat-sink and indium-wrapped microchannel heat-sink, respectively. However, 13W fundamental mode was achieved in the indium-soldered microchannel heat-sink. This obvious progress in beam quality is pretty valuable for the research and design of CW, Q-switch and frequency doubled operation in DPSL.
本文从晶体的内部温度分布推导开始,计算了晶体热透镜焦距,对比了Nd:GdVO4, Nd:YVO4, Nd:YAG三种晶体的热负载比,分析了晶体内部热应力分布,并用LASCAD软件模拟了晶体内部热梯度及应力分布,为我们的散热提供了理论依据。随后,我们又从热传导及流体力学的基本理论出发,重点论述了微通道及铟封的散热原理,为我们下面的实验进行奠定了基础。通过实验我们对比了传统的直通孔式循环水制冷热沉、微通道铟包循环水制冷热沉以及结合了铟封技术的微通道循环水制冷热沉三种散热装置的散热效果,说明了我们采取新型散热装置的良好效果。
实验中,我们采用LD端泵Nd:GdVO4晶棒,平-平腔结构。在泵浦功率为28W的时候,采用传统通孔热沉和微通道热沉分别获得8.66W和10.5W的最大输出功率,光-光效率分别为31%和36%,斜效率分别为38%和42%,另外我们采用微通道热沉并结合铟封技术,在泵浦功率为40W的时候获得最大功率17.5W,且还没有达到输出饱和状态,功率仍呈线性增长,光-光效率和斜效率分别为44%和49%。比较三组数据,我们得出采用铟封微通道热沉的散热效果是明显的。
我们还测得同样的热透镜焦距(350mm)下,采用铟包微通道热沉,晶体吸收的泵浦功率为6.5W,而采用铟封技术的微通道热沉则可以吸收39.5W,这也说明我们采用铟封技术的微通道散热装置对晶体热焦距改善是很明显的。最值得一提的是,我们用光束轮廓分析仪测得了他们的光强分布情况,在传统的通孔式热沉下我们最多只能得到4W的基模输出,采用微通道热沉则可以得到8W的基模输出,而采用微通道结合铟封技术的热沉我们至少可以得到13W基模的高水平,这一基模激光功率的提高,对我们进行连续端泵DPSL调Q、倍频等的研究价值是很可观的。
In the process of pump wavelength transferring, part of the pump power transforms into thermal power inevitably, which will lead to the uneven spatial distribution of temperature inside the crystal, so it will arouse the thermal deformation, thermal stress and birefraction. Thermal effect of laser crystal has already become the bottleneck problem in the power scaling, Q-switch operation and frequency doubling with the rapid development of solid-state laser technology. So we discuss how to solve the thermal dissipation problem in the thesis.
In the paper, modeling of temperature and thermal stress distribution in the crystal, calculation of focal length of thermal-lens and the heat load comparison among Nd:GdVO4, Nd:YVO4 and Nd:YAG were made theoretically. Meanwhile, the temperature field and thermal stress distribution in the crystal were simulated by LASCAD software. All of these provide theoretical basis for our elimination of heat. Then based on the principle of thermal conductivity and fluid mechanics, radiating mechanism of the microchannel heat-sink and the indium solder are discussed, which provides basis for the following experiment.
In the experiment, by comparing the experimental results of the three different kinds of heat-sink, i.e., traditional common heat-sink, indium-wrapped microchannel heat-sink and, indium solder microchannel heat-sink, we demonstrate the good performance of our novel-designed equipment.
In the experiment, we used LD end-pumped Nd:GdVO4 scheme and plano-plano cavity was employed. Under 28W pump power, we obtained 8.66W(in traditional common heat-sink) and 10.5W(in indium-wrapped microchannel heat-sink) output respectively. The optical-optical efficiency is 31% and 36%, slope efficiency is 38% and 42%, correspondingly. But when adding indium-soldered technique to microchannel heat-sink, 17.5W output was obtained under 40W incident pump power, corresponding to the optical-optical efficiency of 44% and slope efficiency of 49%. What’s more, the laser output has not been saturated. Comparing the three groups of data, we can see the effect of indium-soldered microchannel heat-sink is evident.
We also measured the absorbed pump power under the same thermal lens (f=350mm). When using the indium-wrapped heat-sink, the crystal can absorb 6.5W pump power; but for the indium-soldered heat-sink, the crystal can absorb 39.5W pump power, which can also demonstrate superiority of the new technique in thermal dissipation.
Especially, we measured the spatial distribution of transversal mode by the laser beam analyzer. 4W and 8W fundamental mode was obtained in common heat-sink and indium-wrapped microchannel heat-sink, respectively. However, 13W fundamental mode was achieved in the indium-soldered microchannel heat-sink. This obvious progress in beam quality is pretty valuable for the research and design of CW, Q-switch and frequency doubled operation in DPSL.
引文
1 W. Koechner. Solid-state Laser Engineering. Fifth Revised and Updated Edition. Beijing Science Press. 1980:405
2 Li Yan, Chi H.Lee. Thermal effects in end-pumped Nd:phosphate glasses. Appl.phy. 1994,75:1286~1292
3 Y. F. Chen, T.S.Liao, T.M.Huang, K. H. Lin, S. C. Wang. Optimization of Fiber-Coupled Laser-Diode End-Pumped Lasers: Influence of Pump-Beam Quality. IEEE Journal of Quantum Electronics. 1996,32(11):2010~2014
4刘媛媛,方高瞻等.大功率二极管泵浦固体激光器.激光与红外. 2002, 32(3):140~142
5杜晨林,阮双琛,曾峰,于永芹,张怀金. LD单端抽运Nd:GdVO4晶棒16W连续波1.34μm激光器.中国激光. 2004,6(31):672
6于俊华,高静等. LD抽运Nd:GdVO4的激光性能研究.强激光与粒子束. 2005,17(S0)
7徐方华,马丽丽等.激光二极管抽运Nd:GdVO4微片激光器.中国激光. 2005,32(9):1166~1168
8 J.Kong, D.Y.Tang, S.P.Ng, L.M.Zhao, L.J.Qin, X.L.Meng. High-power diode-end-pumped CW Nd:GdVO4 laser. Optics Laser Technology. 2004:51~54
9 N.Pavel, T.Taira. Continuous-wave high-power multi-pass pumped thin-disc Nd:GdVO4 laser. Optics Communications. 2006,260:271~276
10罗亚殡. CPU的发热与散热性能比较.湖南税务高等专科学校学报, 2004,17 (4):50~51
11 http://www.chinadiyer.com/home/cooler/2007/0126/article_45.htm
12陈登科.电子器件冷却技术[J].低温物理学报, 2005, 27 (3 ):255~261
13杨冬梅,徐德好.液冷冷板研究,电子机械工程. 2006,22:4~5
14 J.K.JABCZYNSKI, J.JAGUOE, W.ENDZIAN, and J.KWIATKOWSKI. Thermal-Optic effects in solid-state lasers end pumped by fiber coupled diodes.OPTO-ELECTRONICS REVIEW.2005,13:69~74
15 B.Neuenschwander, R.Weber and H.Weber. Determination of the thermal lens in solid-state lasers with stable cavities.IEEE J.Quantum Electron. 1995,31(6):1082~1087
16 Y.F.Chen, T.M.Huang, C.F.Kao, etal. Optimization in scaling fiber-coupled laser-diode end-pumped lasers to higher power: influence of thermal effect. IEEE J. Quantum Electron. 1997,33(8):14241429
17 Y Kaneda, M. Oka, H. Masuda etal. 7.6W of continuous-wave radiation in TMEoo mode from a laser-diode end-pumped Nd:YAG laser. Opt. Lett. 1992,(17):1003
18刘志刚等.大功率1064nmLD列阵组侧泵浦YAG固体激光器.长春理工大学学报. 2002,Vol.25:58
19 Takunori Taira, J.Saikawa, T.Kobayashi, R.L.Byer.Diode-Pumped Tunable Yb:YAG Miniature Lasers at Room Temperature:Modeling and Experiment. IEEE Journal of Quantum Electronics. 1997,3(1):100~104
20 A.Giesen.Thin-Disk Solid-State Lasers. Solid State Laser Technologies and Femtosecond Phenomena.2004,Vol.5620:113
21陈庆汉,张志斌等. Nd:GdVO4的生长与性能.人工晶体学报. 2002,26(34):213~218
22 W.克希耐尔.固体激光工程.孙文等译.科学出版社.1999:85
23 C.Pfistner, R.Weber, H.P.Weber etc. Thermal beam distortions in End-Pumped Nd:YAG Nd:GSGG and Nd:YLF Rods[J].IEEE J.Quantum Electron., 1994,QE-30(7):1605~1615
24 Z. Xiong, Zhigang G,etc. Detailed Investigation of Thermal Effects in Longitudinally Diode-Pumped Nd:YVO4 Lasers. IEEE Quantum Electronics. 2003,39(8):979~986
25 wupeng gong, mali gong, qiang liu and fuyuan lu. Analysis of transverse mode formation in quasi-three-level microchip lasers. Optical and Quantum Electronics.2005,37:1109–1120
26 M. E. Innocenzi, H. T. Yura, C. L. Fincher, and R. A. Fieids. Thermal modeling of continuous-wave end-pumped solid-state lasers. Appl. Phys. Lett. 1990,56(19):1831-1832
27 D.C. Brown, Nonlinear thermal distortion in YAG rod amplifiers, IEEE Quantum Electron.,1998;34(12); P2383-2393
28 W.A.Clarkson.Thermal effects and their mitigation in end-pumped solid-state lasers.Appl.Phys. 2001,34:2381~2395
29陈树川,陈凌冰.材料物理性能.哈尔滨工业大学出版社. 1999年:12～14
30 A. K. Cousins.Temperature and Thermal Stress Scaling In Finate-Length End-Pumped laser rods.IEEE. QE28,1992:1057~1069
31铁摩辛柯,古地尔著.徐芝纶译.弹性理论.高等教育出版社. 1990:530-544
32 Ananada K. Cousins. Temperature and Thermal Stress Scaling In Finite-Length End-Pumped Laser Rods. IEEE JOURNAL OF QUANTUM ELECTRONICS . 1992,Vol.28:1057~1069
33 D. C. Brown, Heat, fluorescence and stimulated-emission power densities and fraction in Nd:YAG IEEE J. Quantum Electron.1998,34(3):P560-571
34徐国良,王晓墨,乌肠田华,陈维汉.工程传热学.中国电力出版社. 2005: 168~170
35陶文锉.数值传热学(第2版).西安西安交通大学出版社.2001:55
36张良,李云波.流体力学.武汉工业大学出版社. 2006: 82～84
37 R. W. Knight, D. J. Hall, J. S. Goodling, and R. C. Jaeger.Heat Sink Optimization with Application to Microchannels. IEEE Transactionson Components, Hybrids, and Manufacturing Technology.1992 vol.15:832~842
38秦叔经,叶文邦.换热器.化学工业出版社.2003:68~71
39 D.B. Tuckerman. Heat-transfer microstructures for integrated circuits. Lawrence Livermore National Laboratory.1984:169
40吕文强,涂彼,魏彬,武德勇等.高功率二极管激光器模块式微通道冷却器研制.强激光与粒子束, 2005. 17(增刊): 83-86
41徐德好.微通道液冷冷板设计与优化.电子机械工程. 2006,22卷:14～16
42刘云,廖新胜,秦丽,王立军.大功率半导体激光器叠层无氧铜微通道热沉,发光学报, 2005, 26 (1 ):109~113
43 Yitshak Tzuk, Alon Tal, Sharon Goldring, Yaakov Glick, Eyal Lebiush, Guy Kaufman, and Raphael Lavi. Diamond Cooling of High-Power Diode-Pumped Solid-State Lasers. IEEE JOURNAL OF QUANTUM ELECTRONICS. 2004, Vol.40:262~269
44刘英同,杨建村.固体激光器微通道制冷系统的研究.仪器仪表学报, 2002, 23(5)增刊:108~110
45 R. Weber, B. Neuenschwander et al. Cooling schemes for longitudinally diode laser-pumped Nd: YAG rods. IEEE J. Quantum Electron.1998(6):1046~1053
46 http://www.cnjinshu.com/article/bmcl/68/32266.htm
2 Li Yan, Chi H.Lee. Thermal effects in end-pumped Nd:phosphate glasses. Appl.phy. 1994,75:1286~1292
3 Y. F. Chen, T.S.Liao, T.M.Huang, K. H. Lin, S. C. Wang. Optimization of Fiber-Coupled Laser-Diode End-Pumped Lasers: Influence of Pump-Beam Quality. IEEE Journal of Quantum Electronics. 1996,32(11):2010~2014
4刘媛媛,方高瞻等.大功率二极管泵浦固体激光器.激光与红外. 2002, 32(3):140~142
5杜晨林,阮双琛,曾峰,于永芹,张怀金. LD单端抽运Nd:GdVO4晶棒16W连续波1.34μm激光器.中国激光. 2004,6(31):672
6于俊华,高静等. LD抽运Nd:GdVO4的激光性能研究.强激光与粒子束. 2005,17(S0)
7徐方华,马丽丽等.激光二极管抽运Nd:GdVO4微片激光器.中国激光. 2005,32(9):1166~1168
8 J.Kong, D.Y.Tang, S.P.Ng, L.M.Zhao, L.J.Qin, X.L.Meng. High-power diode-end-pumped CW Nd:GdVO4 laser. Optics Laser Technology. 2004:51~54
9 N.Pavel, T.Taira. Continuous-wave high-power multi-pass pumped thin-disc Nd:GdVO4 laser. Optics Communications. 2006,260:271~276
10罗亚殡. CPU的发热与散热性能比较.湖南税务高等专科学校学报, 2004,17 (4):50~51
11 http://www.chinadiyer.com/home/cooler/2007/0126/article_45.htm
12陈登科.电子器件冷却技术[J].低温物理学报, 2005, 27 (3 ):255~261
13杨冬梅,徐德好.液冷冷板研究,电子机械工程. 2006,22:4~5
14 J.K.JABCZYNSKI, J.JAGUOE, W.ENDZIAN, and J.KWIATKOWSKI. Thermal-Optic effects in solid-state lasers end pumped by fiber coupled diodes.OPTO-ELECTRONICS REVIEW.2005,13:69~74
15 B.Neuenschwander, R.Weber and H.Weber. Determination of the thermal lens in solid-state lasers with stable cavities.IEEE J.Quantum Electron. 1995,31(6):1082~1087
16 Y.F.Chen, T.M.Huang, C.F.Kao, etal. Optimization in scaling fiber-coupled laser-diode end-pumped lasers to higher power: influence of thermal effect. IEEE J. Quantum Electron. 1997,33(8):14241429
17 Y Kaneda, M. Oka, H. Masuda etal. 7.6W of continuous-wave radiation in TMEoo mode from a laser-diode end-pumped Nd:YAG laser. Opt. Lett. 1992,(17):1003
18刘志刚等.大功率1064nmLD列阵组侧泵浦YAG固体激光器.长春理工大学学报. 2002,Vol.25:58
19 Takunori Taira, J.Saikawa, T.Kobayashi, R.L.Byer.Diode-Pumped Tunable Yb:YAG Miniature Lasers at Room Temperature:Modeling and Experiment. IEEE Journal of Quantum Electronics. 1997,3(1):100~104
20 A.Giesen.Thin-Disk Solid-State Lasers. Solid State Laser Technologies and Femtosecond Phenomena.2004,Vol.5620:113
21陈庆汉,张志斌等. Nd:GdVO4的生长与性能.人工晶体学报. 2002,26(34):213~218
22 W.克希耐尔.固体激光工程.孙文等译.科学出版社.1999:85
23 C.Pfistner, R.Weber, H.P.Weber etc. Thermal beam distortions in End-Pumped Nd:YAG Nd:GSGG and Nd:YLF Rods[J].IEEE J.Quantum Electron., 1994,QE-30(7):1605~1615
24 Z. Xiong, Zhigang G,etc. Detailed Investigation of Thermal Effects in Longitudinally Diode-Pumped Nd:YVO4 Lasers. IEEE Quantum Electronics. 2003,39(8):979~986
25 wupeng gong, mali gong, qiang liu and fuyuan lu. Analysis of transverse mode formation in quasi-three-level microchip lasers. Optical and Quantum Electronics.2005,37:1109–1120
26 M. E. Innocenzi, H. T. Yura, C. L. Fincher, and R. A. Fieids. Thermal modeling of continuous-wave end-pumped solid-state lasers. Appl. Phys. Lett. 1990,56(19):1831-1832
27 D.C. Brown, Nonlinear thermal distortion in YAG rod amplifiers, IEEE Quantum Electron.,1998;34(12); P2383-2393
28 W.A.Clarkson.Thermal effects and their mitigation in end-pumped solid-state lasers.Appl.Phys. 2001,34:2381~2395
29陈树川,陈凌冰.材料物理性能.哈尔滨工业大学出版社. 1999年:12～14
30 A. K. Cousins.Temperature and Thermal Stress Scaling In Finate-Length End-Pumped laser rods.IEEE. QE28,1992:1057~1069
31铁摩辛柯,古地尔著.徐芝纶译.弹性理论.高等教育出版社. 1990:530-544
32 Ananada K. Cousins. Temperature and Thermal Stress Scaling In Finite-Length End-Pumped Laser Rods. IEEE JOURNAL OF QUANTUM ELECTRONICS . 1992,Vol.28:1057~1069
33 D. C. Brown, Heat, fluorescence and stimulated-emission power densities and fraction in Nd:YAG IEEE J. Quantum Electron.1998,34(3):P560-571
34徐国良,王晓墨,乌肠田华,陈维汉.工程传热学.中国电力出版社. 2005: 168~170
35陶文锉.数值传热学(第2版).西安西安交通大学出版社.2001:55
36张良,李云波.流体力学.武汉工业大学出版社. 2006: 82～84
37 R. W. Knight, D. J. Hall, J. S. Goodling, and R. C. Jaeger.Heat Sink Optimization with Application to Microchannels. IEEE Transactionson Components, Hybrids, and Manufacturing Technology.1992 vol.15:832~842
38秦叔经,叶文邦.换热器.化学工业出版社.2003:68~71
39 D.B. Tuckerman. Heat-transfer microstructures for integrated circuits. Lawrence Livermore National Laboratory.1984:169
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