高功率LD泵浦固体激光器热效应研究
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摘要
二极管泵浦固体激光器(DPSSL)相对于传统的灯泵浦固体激光器已大大降低了热效应,但是随着泵浦光功率的进一步提高,激光介质的热效应仍是限制DPSSL向高功率高光束质量发展的重要因素。本论文采用有限元数值模拟和实验观测相结合的方法,研究了重复频率和热容模式二极管泵浦固体激光器的热效应问题,其中对于重复频率DPSSL分为端面泵浦和侧面泵浦两种泵浦方式,进行了重点研究。主要研究结果如下:
1.对于激光二极管阵列(LDA)重复频率端面泵浦的大口径Nd:YLF片状放大器,介质的温升和最大热应力与泵浦功率基本呈线性关系,有效泵浦功率密度达到10 kW/cm2时,普通冷却条件下介质可能发生热致断裂;对于相同输出功率的二极管阵列,耦合后能量在空间上呈超高斯分布时热效应最小。
2.在重复频率DPSSL中,重复频率的增加将明显增加介质的温升和热应力等热效应;而增大表面的强迫对流换热系数,将会降低介质的最高温升,但最大热应力不一定降低,单纯增加表面换热能力不能保证介质安全工作。结论得到了实验验证。
3.对于环形LDA泵浦棒状放大器,以泵浦阵列半径为出发点,讨论一定增益下最高效泵浦效率方案的设计。研究表明,对于相同的增益指标,介质直径越小,所需泵浦功率和热效应也越小。
4.热容模式下的LD泵浦固体激光器虽然克服了重复频率DPSSL表面冷却带来的一些热问题,但由泵浦不均匀性引发的一系列热效应不能忽略,对输出功率和光束质量都产生了一定影响。
本文的研究结果,对于高功率LD泵浦固体激光器的设计和运行具有一定的参考意义。
Compared with traditional solid-state lasers pumped by flash lamps, diode pumped solid-state laser (abbreviated to DPSSL) has lower thermal effect. But, to a certain extent, thermal effects still restrict the DPSSL from giving out a high power and high energy output as desired. In this dissertation, thermal effects of repeated-pulse solid-state laser and heat capacity laser, especially end-pumped and side-pumped repeated-pulse laser, have been analyzed by finite element method and IR camera. The main results obtained in the dissertation can be summarized as follows:
Firstly, a finite element thermal model of repeated pulse LDA (Laser Diode Array) end-pumped laser crystal Nd:YLF is established. 3D and transient distributions of temperature and thermal stress in laser crystal were calculated. The results show that the maximal temperature and thermal stress increase with pump power linearly, and fracture due to thermal stress may occur when effective pump energy up to 10 kW/cm2; the thermal effect of crystal under Super-Gaussian transverse distribution is the weakest when pumped by same power.
Secondly, in end-pumped repeated pulse laser, thermal effects rise definitely when the frequency increases. When the heat transfer coefficient increase, the maximal temperature will decrease, but the maximal thermal stress may not decrease, the crystal can’t work safely only by the increase of heat transfer coefficient. Some of the conclusions have been verified by experiment.
Thirdly, pump efficiency and thermal effect in ring-LDA pulse-side-pumped Nd:glass laser have been studied. When designing a pump structure of specified gain amplifier, we start with LDA ring radius, and the highest pump efficiency can be achieved. Based on the same gain coefficient, the smaller glass radius is, the lower pump power needed and the lower thermal effects are.
Finally, although LDA pumped heat capacity laser has partially eliminate the thermal effect of high average power laser, thermal effect due to the non-uniform pump can not be neglected. By means of 3D heat transfer codes and experimental measurement, the temperature and thermal stress distribution have been researched.
The conclusions in this dissertation can be used to optimize and operate the high power DPSSL.
1.对于激光二极管阵列(LDA)重复频率端面泵浦的大口径Nd:YLF片状放大器,介质的温升和最大热应力与泵浦功率基本呈线性关系,有效泵浦功率密度达到10 kW/cm2时,普通冷却条件下介质可能发生热致断裂;对于相同输出功率的二极管阵列,耦合后能量在空间上呈超高斯分布时热效应最小。
2.在重复频率DPSSL中,重复频率的增加将明显增加介质的温升和热应力等热效应;而增大表面的强迫对流换热系数,将会降低介质的最高温升,但最大热应力不一定降低,单纯增加表面换热能力不能保证介质安全工作。结论得到了实验验证。
3.对于环形LDA泵浦棒状放大器,以泵浦阵列半径为出发点,讨论一定增益下最高效泵浦效率方案的设计。研究表明,对于相同的增益指标,介质直径越小,所需泵浦功率和热效应也越小。
4.热容模式下的LD泵浦固体激光器虽然克服了重复频率DPSSL表面冷却带来的一些热问题,但由泵浦不均匀性引发的一系列热效应不能忽略,对输出功率和光束质量都产生了一定影响。
本文的研究结果,对于高功率LD泵浦固体激光器的设计和运行具有一定的参考意义。
Compared with traditional solid-state lasers pumped by flash lamps, diode pumped solid-state laser (abbreviated to DPSSL) has lower thermal effect. But, to a certain extent, thermal effects still restrict the DPSSL from giving out a high power and high energy output as desired. In this dissertation, thermal effects of repeated-pulse solid-state laser and heat capacity laser, especially end-pumped and side-pumped repeated-pulse laser, have been analyzed by finite element method and IR camera. The main results obtained in the dissertation can be summarized as follows:
Firstly, a finite element thermal model of repeated pulse LDA (Laser Diode Array) end-pumped laser crystal Nd:YLF is established. 3D and transient distributions of temperature and thermal stress in laser crystal were calculated. The results show that the maximal temperature and thermal stress increase with pump power linearly, and fracture due to thermal stress may occur when effective pump energy up to 10 kW/cm2; the thermal effect of crystal under Super-Gaussian transverse distribution is the weakest when pumped by same power.
Secondly, in end-pumped repeated pulse laser, thermal effects rise definitely when the frequency increases. When the heat transfer coefficient increase, the maximal temperature will decrease, but the maximal thermal stress may not decrease, the crystal can’t work safely only by the increase of heat transfer coefficient. Some of the conclusions have been verified by experiment.
Thirdly, pump efficiency and thermal effect in ring-LDA pulse-side-pumped Nd:glass laser have been studied. When designing a pump structure of specified gain amplifier, we start with LDA ring radius, and the highest pump efficiency can be achieved. Based on the same gain coefficient, the smaller glass radius is, the lower pump power needed and the lower thermal effects are.
Finally, although LDA pumped heat capacity laser has partially eliminate the thermal effect of high average power laser, thermal effect due to the non-uniform pump can not be neglected. By means of 3D heat transfer codes and experimental measurement, the temperature and thermal stress distribution have been researched.
The conclusions in this dissertation can be used to optimize and operate the high power DPSSL.
引文
[1] 克希耐尔 W. 固体激光工程[M]. 北京:科学出版社,2002
[2] R.Newman. Excitation of the Nd3+ fluorescence in CaWO4 by recombination radiation in GaAs. Journal of Applied Physics 1963,34(2):437
[3] R.J.Keyes and T.M.Quist, et.al. Injection Iuminescent pumping of CaF2:U3+ with GaAs diode lasers. Applied Physics Letters 1964,4(3)
[4] J.G.Endriz, et al. High power diode laser arrays. IEEE J.Q.E.,28(4),952
[5] J.Hein S.Podleska and M.Siebold et al. Diode-pumped chirped pulse amplification to the joule level. Applied Physics B, 79,419-422(2004)
[6] J.Vetrovec and R.Rice. Thermal management system for solid-state high-energy laser. 5th SSDLTR 2002 Technical digest. Power-5
[7] A.K.Cousins, Temperature and Thermal Stress Scaling In Finite-Length End-Pumped Laser Rods,IEEE J Q E.28,1057(1992)
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[9] M.E.Innocenzi, H.T.Yura, and C.L.Fincher et al, Thermal modeling of continous-wave end-pumped solid-state lasers, Applied Physics Letters 1990,56(19):1831
[10] C.Pfistner,R.Weber,H.P.Weber,Thermal Beam Distortions in End-Pumped Nd:YAG,Nd:GSGG,and Nd:YLF Rods,IEEE J Q E.30.1605(1994)
[11] M.Pollnau,P.J.Hardman,M.A.Kern,Upconversion-induced heat generation and thermal lensing in Nd:YLF and Nd:YAG,Physics.Rev.B 58,16076(1998)
[12] X.Peng,L.Xu,A.Asundi,Power Scaling of Diode-pumped Nd:YVO4 Lasers,IEEE J Q E.38.1291(2002)
[13] X.Peng,L.Xu,A.Asundi,Thermal lensing effects for diode-end-pumped NdYVO4 and NdYAG lasers,Opt.Eng.43.2454(2004)
[14] X.Peng,L.Xu,A.Asundi,High-power efficient continuous-wave TEM00 intracavity frequency-doubled diode-pumped Nd:YLF laser,Appl.Opt.44.800(2005)
[15] A.Bayramian,R.Beach,C.Bibeau,FY96-98 Summary Report Mercury:Next Generation Laser for High Energy Density Physics SI-014
[16] 於海武,郑万国,贺少勃 等,神光Ⅲ原型装置主放大器剩余热畸变模拟研究,中国激光,2001,28(5)
[17] 於海武,郑万国,王成程 等,单口径片状放大器光束波前畸变热恢复研究,中国激光,2001,28(11)
[18] Haiwu Yu, Wanguo Zheng, Chengcheng Wang, et al, Thermal-recovery optimization of the SG-Ⅲ prototype, Opt. Eng.,2001,40(1):126-131
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[20] 张玲,杨少辰,李文博,LD 侧面泵浦 Nd:YAG 激光器的热效应研究,激光与红外,2003,Vol.33,37-39
[21] 沈鸿元,四方晶系 Nd:YLF 晶体的热效应,科学通报,1996 Vol.41,1039-1043
[22] 郑加安,赵圣之,张行愚,等,LD 纵向泵浦固体激光器参数优化,光电子·激光,2000,11(5)
[23] 郑加安,赵圣之,王青圃,等,晶体热效应对 LD 端面泵浦固体激光器优化设计的影响,光子学报,2001,30(6)
[24] 贾伟,大口径高效率激光二极管阵列泵浦技术研究,国防科技大学博士学位论文(2005)
[25] 欧群飞,高功率二极管抽运固体激光器的热效应分析,四川大学博士学位论文(2005)
[26] 贾伟,李明中,张小民. 美国 Mercury 系统发展近况,激光与光电子学进展 2004;41(5).
[27] 丁磊,贾伟,李明中. 美国 Mercury 系统的最新进展,激光与光电子学进展 2004,41(8)
[28] 於海武,徐美健,段文涛 等, 惯性聚变能源激光驱动器研究进展,激光与光电子学进展 2006,43(9)
[29] 孔祥谦 编著,有限单元法在传热学中的应用(第三版),科学出版社,1998
[30] 贾伟,李明中,丁磊,等. 大口径高功率激光二极管阵列端面泵浦技术研究,强激光与粒子束,2005,17(S0)
[31] 邵怀宗 吕百达. 激光二极管泵浦晶体的研究进展. 红外与激光工程 1997;26(2):13-17
[32] 梁峰,冯国英,欧群飞,等. 重复脉冲泵浦管状固体激光器的介质温升,强激光与粒子束,2005,17(5):685-688
[33] 陈登科. 电子器件冷却技术. 低温物理学报,2005,27(3):255-262.
[34] 罗亦鸣,李明中,秦兴武,等. 大功率环形 LD 侧面泵浦 Nd:YLF 激光器的特性,强激光与粒子束,2002,14(3):331-333
[35] 秦兴武,李明中,罗亦鸣,等. LD 泵浦的 Nd:YLF 激光放大技术,中国核科技报告,2003,01:55-66
[36] Walters C T , Dulaney J L , Campbell B E , et al . Nd:glass burst laser wit h kW average power output [J].IEEE J Quant Electr , 1995 ,31 (2) : 293～299.
[37] Albrecht G F , George E V , Krupke W F , et al . High energy burst s f rom a solid state laser operated in t he heat capacity limited regime[ P] .Patent Number : 5526372 , Jun 11 , 1996.阿
[38] Albrecht G F , Sut ton S B , George E V , et al . The heat capacity disk laser [A] . Proc of SPIE[C] . 1998 , 3343 :661～666.
[39] Dane C B , Flat h L , Rot ter M , et al . Army solid2state laser program: Design , operation , and mission analysis for heat capacity laser [ A ] .Proc of 14th Annual Solid2State and Diode Laser Technology Review[ C] . Albuquerque , NM ,2001.
[40] Rotter M D , Dane C B , Gonzales S , et al . Recent progress in diode-pumped , solid-state heat-capacity lasers[ R] . UCRL-JC-151482. 2003.
[41] Rotter M D , Dane C B , Fochs S , et al . Solid-state heat-capacity lasers : good candidates for t he marketplace[J].Photonics Spectra ,2004 :44～52.
[42] 蒋新颖,热效应对固体热容激光器输出特性研究,中国工程物理研究院学位论文(2006)
[43] J.D.Foster and L.M.Osterink.Thermal Effects in a Nd:YAG Laser.[J]TouRNAL OFAPPLIED PHYSICS,1970;41:3656~3663
[44] ZHANG Shen-jin QU Qun-fei,FENG Gao-ying et al.. Analysis of transient temperature distribution in laser rod pumped by repetively pulsed high-power ring-LDA. [J] HIGH POWER LASER AND PARTICLE BEAMS,2004;16(2):145～148
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[2] R.Newman. Excitation of the Nd3+ fluorescence in CaWO4 by recombination radiation in GaAs. Journal of Applied Physics 1963,34(2):437
[3] R.J.Keyes and T.M.Quist, et.al. Injection Iuminescent pumping of CaF2:U3+ with GaAs diode lasers. Applied Physics Letters 1964,4(3)
[4] J.G.Endriz, et al. High power diode laser arrays. IEEE J.Q.E.,28(4),952
[5] J.Hein S.Podleska and M.Siebold et al. Diode-pumped chirped pulse amplification to the joule level. Applied Physics B, 79,419-422(2004)
[6] J.Vetrovec and R.Rice. Thermal management system for solid-state high-energy laser. 5th SSDLTR 2002 Technical digest. Power-5
[7] A.K.Cousins, Temperature and Thermal Stress Scaling In Finite-Length End-Pumped Laser Rods,IEEE J Q E.28,1057(1992)
[8] U.O.Farrukh, A.M.Buoncristiani, and C.E.Byvik, An analysis of the temperature distribution in finite solid-state laser rods, IEEE J Q E. 24, 2253(1988)
[9] M.E.Innocenzi, H.T.Yura, and C.L.Fincher et al, Thermal modeling of continous-wave end-pumped solid-state lasers, Applied Physics Letters 1990,56(19):1831
[10] C.Pfistner,R.Weber,H.P.Weber,Thermal Beam Distortions in End-Pumped Nd:YAG,Nd:GSGG,and Nd:YLF Rods,IEEE J Q E.30.1605(1994)
[11] M.Pollnau,P.J.Hardman,M.A.Kern,Upconversion-induced heat generation and thermal lensing in Nd:YLF and Nd:YAG,Physics.Rev.B 58,16076(1998)
[12] X.Peng,L.Xu,A.Asundi,Power Scaling of Diode-pumped Nd:YVO4 Lasers,IEEE J Q E.38.1291(2002)
[13] X.Peng,L.Xu,A.Asundi,Thermal lensing effects for diode-end-pumped NdYVO4 and NdYAG lasers,Opt.Eng.43.2454(2004)
[14] X.Peng,L.Xu,A.Asundi,High-power efficient continuous-wave TEM00 intracavity frequency-doubled diode-pumped Nd:YLF laser,Appl.Opt.44.800(2005)
[15] A.Bayramian,R.Beach,C.Bibeau,FY96-98 Summary Report Mercury:Next Generation Laser for High Energy Density Physics SI-014
[16] 於海武,郑万国,贺少勃 等,神光Ⅲ原型装置主放大器剩余热畸变模拟研究,中国激光,2001,28(5)
[17] 於海武,郑万国,王成程 等,单口径片状放大器光束波前畸变热恢复研究,中国激光,2001,28(11)
[18] Haiwu Yu, Wanguo Zheng, Chengcheng Wang, et al, Thermal-recovery optimization of the SG-Ⅲ prototype, Opt. Eng.,2001,40(1):126-131
[19] 张玲,杨少辰,路绪鹏,等,LD 端面泵浦 Nd:YAG 激光器的热效应研究,北方交通大学学报,2002,26(6):45-47
[20] 张玲,杨少辰,李文博,LD 侧面泵浦 Nd:YAG 激光器的热效应研究,激光与红外,2003,Vol.33,37-39
[21] 沈鸿元,四方晶系 Nd:YLF 晶体的热效应,科学通报,1996 Vol.41,1039-1043
[22] 郑加安,赵圣之,张行愚,等,LD 纵向泵浦固体激光器参数优化,光电子·激光,2000,11(5)
[23] 郑加安,赵圣之,王青圃,等,晶体热效应对 LD 端面泵浦固体激光器优化设计的影响,光子学报,2001,30(6)
[24] 贾伟,大口径高效率激光二极管阵列泵浦技术研究,国防科技大学博士学位论文(2005)
[25] 欧群飞,高功率二极管抽运固体激光器的热效应分析,四川大学博士学位论文(2005)
[26] 贾伟,李明中,张小民. 美国 Mercury 系统发展近况,激光与光电子学进展 2004;41(5).
[27] 丁磊,贾伟,李明中. 美国 Mercury 系统的最新进展,激光与光电子学进展 2004,41(8)
[28] 於海武,徐美健,段文涛 等, 惯性聚变能源激光驱动器研究进展,激光与光电子学进展 2006,43(9)
[29] 孔祥谦 编著,有限单元法在传热学中的应用(第三版),科学出版社,1998
[30] 贾伟,李明中,丁磊,等. 大口径高功率激光二极管阵列端面泵浦技术研究,强激光与粒子束,2005,17(S0)
[31] 邵怀宗 吕百达. 激光二极管泵浦晶体的研究进展. 红外与激光工程 1997;26(2):13-17
[32] 梁峰,冯国英,欧群飞,等. 重复脉冲泵浦管状固体激光器的介质温升,强激光与粒子束,2005,17(5):685-688
[33] 陈登科. 电子器件冷却技术. 低温物理学报,2005,27(3):255-262.
[34] 罗亦鸣,李明中,秦兴武,等. 大功率环形 LD 侧面泵浦 Nd:YLF 激光器的特性,强激光与粒子束,2002,14(3):331-333
[35] 秦兴武,李明中,罗亦鸣,等. LD 泵浦的 Nd:YLF 激光放大技术,中国核科技报告,2003,01:55-66
[36] Walters C T , Dulaney J L , Campbell B E , et al . Nd:glass burst laser wit h kW average power output [J].IEEE J Quant Electr , 1995 ,31 (2) : 293～299.
[37] Albrecht G F , George E V , Krupke W F , et al . High energy burst s f rom a solid state laser operated in t he heat capacity limited regime[ P] .Patent Number : 5526372 , Jun 11 , 1996.阿
[38] Albrecht G F , Sut ton S B , George E V , et al . The heat capacity disk laser [A] . Proc of SPIE[C] . 1998 , 3343 :661～666.
[39] Dane C B , Flat h L , Rot ter M , et al . Army solid2state laser program: Design , operation , and mission analysis for heat capacity laser [ A ] .Proc of 14th Annual Solid2State and Diode Laser Technology Review[ C] . Albuquerque , NM ,2001.
[40] Rotter M D , Dane C B , Gonzales S , et al . Recent progress in diode-pumped , solid-state heat-capacity lasers[ R] . UCRL-JC-151482. 2003.
[41] Rotter M D , Dane C B , Fochs S , et al . Solid-state heat-capacity lasers : good candidates for t he marketplace[J].Photonics Spectra ,2004 :44～52.
[42] 蒋新颖,热效应对固体热容激光器输出特性研究,中国工程物理研究院学位论文(2006)
[43] J.D.Foster and L.M.Osterink.Thermal Effects in a Nd:YAG Laser.[J]TouRNAL OFAPPLIED PHYSICS,1970;41:3656~3663
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