LD端泵浦Yb：YAG直接键合波导激光器的研究
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摘要
Yb:YAG在高功率、超短脉冲方面有着比Nd:YAG优异得多的特性,如适合激光二极管(LD)泵浦,光-光转换效率高,高掺杂浓度,无激发态吸收以及上转换,荧光寿命长等优点得到了人们的广泛关注。然而,由于Yb:YAG晶体为准三能级系统,使得激光器的运转状态对于激光晶体的工作温度比较敏感,为了提高和改善散热能力,我们利用激光晶体的直接键合技术,构成Sapphire/Yb:YAG/Sapphire复合晶体,期望利用Sapphire晶体良好的散热性和平板波导结构来改善Yb:YAG激光系统的性能。因此,对Sapphire/Yb:YAG/Sapphire复合晶体平板激光器的温度场,应力场进行了分析,并提出了连续LD端面泵浦该激光器的理论分析与优化设计。
本论文主要工作如下:
(1)综述了Yb:YAG固体激光器的发展过程及现状,和国内外激光介质热分析的现状及复合晶体平面波导激光器在降低介质热效应方面的优势。
(2)建立了用于分析端面泵浦Sapphire/Yb:YAG/Sapphire复合晶体平板激光介质中的热应力模型。
(3)用有限元方法及专业软件数值计算了简单形状激光介质中的热应力分布,并与其解析计算结果进行比较,确定数值模拟计算的精度及可靠性。
(4)以二维模型为基础,对端面泵浦Sapphire/Yb:YAG/Sapphire复合晶体平板激光介质的热效应进行了理论分析和模拟计算,并研究了影响复合晶体波导激光介质中热应力的因素,为进一步提高激光质量、增大激光输出功率提供了依据。
(5)从准三能级系统的速率方程出发,推导出了二极管连续端面泵浦固体Yb:YAG激光器的速率方程,提出了连续LD端面泵浦激光器的理论分析与优化,包括计算激光晶体的最佳长度,激光器的最佳透射率等参数。
For generation of high power ultrashort optical pulses, Yb: YAG is becoming a kind of popular laser material with more attractive features than Nd: YAG, such as its suitability for laser diode (LD) pumping, high slope efficiency, high doping concentration, no excited state absorption as well as up conversion and the advantages of a long fluorescence lifetime. However, the running state of lasers is quite sensitive to laser crystal temperature due to the three-level system of Yb: YAG crystal. In order to enhance and improve the capacity of heat dissipation of Yb: YAG laser and to improve the Yb: YAG laser system performance, a piece of Sapphire / Yb : YAG / Sapphire composite laser crystal which is made by direct bonding crystal technology is used as gain material to take the advantage of good heat conduction of Sapphire and the thin slab waveguide structure. Therefore, the temperature field and stress field in the Sapphire / Yb: YAG / Sapphire composite crystal slab laser are analyzed, and the LD end-pumped laser design analysis and theoretical optimization are proposed.
(1) The development and the current states of Yb: YAG solid-state lasers are reviewed. The work of thermal analysis of laser medium and the advantages of using direct-bounding laser crystal to reduce the thermal effects are described.
(2) The thermal stress model of end-pumped Sapphire/Yb : YAG/Sapphire waveguide laser is established.
(3) The analytical solutions of temperature field and thermal stress field in the gain medium of simple laser structure are analyzed based on both theoretical method and the finite element method, to make sure the correctness and accurary of the finite element method.
(4) Based on two-dimensional model, the thermal effect of single end-pumped Sapphire/Yb:YAG/Sapphire planar waveguide lasers is analyzed theoretically and calculated numerically. Factors which could impact the thermal stress of composite planar waveguide laser are discussed to provide the evidence for improvement of the quality and output power of this laser.
(5) The rate equations for three-level system of CW Yb:YAG lasers is set up. And the theoretical analysis and optimization of LD end-pumped laser are proposed including the optimizational length of laser media and the optimizational transmition of output couplers.
本论文主要工作如下:
(1)综述了Yb:YAG固体激光器的发展过程及现状,和国内外激光介质热分析的现状及复合晶体平面波导激光器在降低介质热效应方面的优势。
(2)建立了用于分析端面泵浦Sapphire/Yb:YAG/Sapphire复合晶体平板激光介质中的热应力模型。
(3)用有限元方法及专业软件数值计算了简单形状激光介质中的热应力分布,并与其解析计算结果进行比较,确定数值模拟计算的精度及可靠性。
(4)以二维模型为基础,对端面泵浦Sapphire/Yb:YAG/Sapphire复合晶体平板激光介质的热效应进行了理论分析和模拟计算,并研究了影响复合晶体波导激光介质中热应力的因素,为进一步提高激光质量、增大激光输出功率提供了依据。
(5)从准三能级系统的速率方程出发,推导出了二极管连续端面泵浦固体Yb:YAG激光器的速率方程,提出了连续LD端面泵浦激光器的理论分析与优化,包括计算激光晶体的最佳长度,激光器的最佳透射率等参数。
For generation of high power ultrashort optical pulses, Yb: YAG is becoming a kind of popular laser material with more attractive features than Nd: YAG, such as its suitability for laser diode (LD) pumping, high slope efficiency, high doping concentration, no excited state absorption as well as up conversion and the advantages of a long fluorescence lifetime. However, the running state of lasers is quite sensitive to laser crystal temperature due to the three-level system of Yb: YAG crystal. In order to enhance and improve the capacity of heat dissipation of Yb: YAG laser and to improve the Yb: YAG laser system performance, a piece of Sapphire / Yb : YAG / Sapphire composite laser crystal which is made by direct bonding crystal technology is used as gain material to take the advantage of good heat conduction of Sapphire and the thin slab waveguide structure. Therefore, the temperature field and stress field in the Sapphire / Yb: YAG / Sapphire composite crystal slab laser are analyzed, and the LD end-pumped laser design analysis and theoretical optimization are proposed.
(1) The development and the current states of Yb: YAG solid-state lasers are reviewed. The work of thermal analysis of laser medium and the advantages of using direct-bounding laser crystal to reduce the thermal effects are described.
(2) The thermal stress model of end-pumped Sapphire/Yb : YAG/Sapphire waveguide laser is established.
(3) The analytical solutions of temperature field and thermal stress field in the gain medium of simple laser structure are analyzed based on both theoretical method and the finite element method, to make sure the correctness and accurary of the finite element method.
(4) Based on two-dimensional model, the thermal effect of single end-pumped Sapphire/Yb:YAG/Sapphire planar waveguide lasers is analyzed theoretically and calculated numerically. Factors which could impact the thermal stress of composite planar waveguide laser are discussed to provide the evidence for improvement of the quality and output power of this laser.
(5) The rate equations for three-level system of CW Yb:YAG lasers is set up. And the theoretical analysis and optimization of LD end-pumped laser are proposed including the optimizational length of laser media and the optimizational transmition of output couplers.
引文
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[2]P.Lacovara,H.K.Chai et al.,Room-temperature diode-pumped Yb:YAG Laser,J.Opt.Lett.,1991,16(14):1089～1091.
[3]E.C Honea,R.J.Beach,High-power dual-rod Yb:YAG laser,J.Opt.Lett., 2000,25(11):805～807.
[4]J.Ausder Au,G.J.Spuhler et a1.,16.2W-average power from a diode -pumped femtosecond Yb:YAG thin disk laser,J.Opt.Lett., 2000,25(11):859～861.
[5]张丽哲,戴建明等,全固化可调谐Yb:YAG激光器,中国激光,2001,28(10):873～876.
[6]A.Giesen,M.Karszewski et a1.,Multiwatt-diode-pumped Yb:YAG thin disk laser continuously tunable between 1018 and 1053nm,J.Opt.Lett.,1991,20(7):713.
[7] F.Brenner,R.Paschotta et a1.,Widely tunable pulse durations from a passively mode-locked thin-disk Yb:YAG laser,J.Opt.Lett.,2001,26(6):379～381.
[8] D.S.Sumida,T.Y.Fan et al.,Effect of radiation trapping on fluores -cence lifetime and emtission cross section measurements in solid-state laser media,J.Opt.Lett.,19(17):1343～1346.
[9]杨培志,邓佩珍等,Yb:YAG晶体的光谱和激光性能,光学学报,1999,19(1):132～l35.
[10]徐晓东,赵志伟,宋平新等,高掺杂浓度Yb:YAG晶体的生长及光谱性能,中国激光,2004,31(8):955～958.
[11]Fan T Y,Heat generation in Nd:YAG and Yb:YAG,J.IEEE Quantum Electron,1993,QE-29:1457～1459.
[12]Ross,YAG laser operation by semieonductor laser pumping,J.Proc.IEEE,1968,56:196～197.
[13]Kruke W F,Chase L L,Ground-state depleted solid-state lasers prin -ciple,characteristic and scaling,J.Opt.,Quantum Electronics,1990,22:S1～S22.
[14]Lacovara P,Choi H K ,Wang C A et al., Room-temperature diode-pumped Yb:YAG laser,J.Opt.Lett.,1991,16[14]1089～1091.
[15]Deloach L D,Payne S A,Chaseetal L L,valuation of absorption and emission properties of Yb3+ doped crystals for laser applications,J.IEEE .Quant.Electron.,1993,QE-29(4):1179～1190.
[16]Marshall C D,Smith L K,Beachetal R J,Diode-pumped Yb:Sr5(PO4)3F laser performance,J.IEEE.Quant.Electron.,1996,QE-32(4):650～656.
[17]邱宏伟,杨培志,Yb:YAG激光晶体的高温退火和高浓度掺杂效应,J.中国激光,2000,20(3):339～443.
[18]Giesen A,Brauch U,Johannsen I et a1.,High-power near diffraction -limited and single-frequency operation of Yb:YAG thin disk laser, J.Opt.Soc.America.,1996,11～13.
[19]Karszewski M,Brauch U et a1.,100W TEM00 operation of Yb:YAG thin disc laser with high efficiency,J.Opt.Soc.Amer.,1998,19:125.
[20]Li Chao,Xu Zhen,Li Junlin et a1.,Diode pumped Yb:YAG thin disk laser achieves 16W CW output, J.Chinese Journal of Quantum Electroni -cs,2002,19(2):104-108.
[21]Jun Dong,Michael Bass,Dependence of the Yb3+ emission crosss section and lifetime on temperature and concentration in yttrium luminumg garnet,J.OPtieal Soeiety of America,2003,20(9),1975～1979.
[22]Laura D. DeLoach , StePhen A.Payne,Evaluation of Absorption and Emission Properties Yb3+ Dopede Crystals for Laser Applications,J. IEEE Quantuam Electronins,1993,19(4),1179～1191.
[23]Reinberg A R,Risenberg L A, Brown R M et al.,GaAs:Si LED Pumped Yb:doped YAG laser,Appl.Phys.Lett.,1971,19(1):11～13.
[24]Hongbin Yin,Peizhen Deng,Fuxi Gan et al.,Defects in Yb:YAG crys -tal,J.Appl.Phys.,1998,830:3825～3828.
[25]Jun Dong,Akira Shirakaw et al.,Efficient laser oseillation of Yb:Y3A15O12 single cryslal grown by temperature gradient techniqu -e.Appl.Phys.Lett.,2006,88:1615～1618.
[26]D.S.Sumida,H.Bruesselbach,R.W.Byren et al.,High-Power Yb:YAG rod oscillators and amplifiers,SPIE,1998,3265:100～103.
[27]C Stewen,K Contag et al.,A 1-kW CW thin disc laser ,J.IEEE.Quantum Election.,2000,6(4):650～657.
[28]J.Wallace,Commereial disk laser reaches 4-kW output,Laser Focus World,2004,19:122～126.
[29]Y.Kalisky,C.Labbe,K.Waiehm et al.,Passively Q-switched diode–Pumpe -d Yb:YAG laser using Cr4+-doped garnets,Opt.Mater,2002,19(4):403～407.
[30]T.Y.Fan,S.Klunk,GHenein,Diode-Pumped Q-switched Yb:YAG laser, OPt. Lett.,1993,18(6):423～427.
[31]D.S.Sumida,T.Y.Fan,A 50mJ per transversely diode pumped Yb:YAG laser at room temperature,J.CLEO.,1994:419～420.
[32]A Giesen,H Hugel et a1.,Scalable concept for Diode-pumped hig - en-power solid-state laers,J.Appl.Phy B.,1994,58(4):365～372.
[33]T S Rutherford,W M Tulloch,E K Gustafson et a1.,Ed-pumped quasi-three-level slab laser:design and power scalingf, J.IEEE . Quantum Electron.,2000,36(2):205～219.
[34]J.Dong,P.Deng,Y.Liu et al.,Passively Q-switched Yb:Y AG laser with Cr:YAG as the saturable absorber,J.Appl.Opt.,2001,40(24):4303～4307.
[35] E.C.Honea,R.J.Beach,S.C.Mitchell et al.,High-Power dual-rod Yb:YAG laser,Opt.Lett.,2000,25(11):805～900.
[36]Q.Liu,M.Gong,F.Lu et al.,520-W continuous-wave diode corner-pumped composite Yb:YAG slab laser,J.Opt.Lett.,2005,30(7):726～731.
[37]Masaki Tsunekane, Traian Dascalu, High-power, diode edge-pumped, single-crystal Yb:YAG /ceramic YAG composite microchip Yb:YAG laser for material processing,OSA/CLEO 2005.
[38]Mali Gong,Fuyuan Lu,Efficient corner-pumped Yb:YAG/YAG composite slab laser,J.Optical Society of America., 2006,45(16):3806～3810.
[39]施翔睿,石鹏,Yb:YAG薄片激光介质的温度效应,J.光学学报,2001,21(10):1268～1271.
[40]Farru Chou,An analysis of the temperature distribution in finite solid statelaser rods,J.IEEE Quantum Electron.,1988,24(11):2253～2264.
[41]杨鸿儒,左铁钏,全固态小型Yb:YAG激光器热效应及输出特性的研究,J.光子学报,2003,32(8):907～910.
[42]Sugiyama A,Fukuyama H et al.,Direct bonding of Ti:sapphire laser crystals,Appl.Opt.,1998,18:88～92.
[43]Sugiyama A,Fukuyama H et al.,Evaluations of bonded region in a direct bonded Ti:sapphire laser crystal,CLEO/Pacific Rim 2001,2001,WH3-3:Ⅱ460～Ⅱ461.
[44]Sugiyama A,Fukuyama H,et al.,Nd:YVO4 and YVO4 laser crystals Integration by a direct bonding technique,J.Proc.SPIE.,2002,4944:361～368.
[45]J. M. Eggleston, T. J. Kane, K. Kuhn et al., The slab geometry laser-part I: theory, IEEE, J. quantum electronics, 1984, 20(3), 289～301.
[46]吴家龙等,弹性力学,北京:高等教育出版社,2001:277～282.
[47]张亚鸥等,ANSYS7.0有限元分析实用教程,清华大学出版社,2004:1～7.
[48]J.M.Eggleston,T.J.Kane et al., The Slab Geometry Laser-Part I: Theory,J. IEEE Journal of Quantum Electrnics,1984,20(3):289～301.
[49]H.Lee,H.E.Meissner,O.R.Meissner,Adhesive-free bonded (AFB) CVD diamond/sapphire and CVD diamond/YAG crystal composites,Laser Source and System Technology for Defense and Security II Proceedings of the SPIE , 2006, Vol.6216.
[50]David C. Brown, Ultrahigh-Average-Power Diode-Pumped Nd: YAG and Yb:YAG Laser, IEEE J. Quantum Electronics, Vol. 33: 861～873.
[51]严宗达等,热应力,高等教育出版社,1993:1.
[2]P.Lacovara,H.K.Chai et al.,Room-temperature diode-pumped Yb:YAG Laser,J.Opt.Lett.,1991,16(14):1089～1091.
[3]E.C Honea,R.J.Beach,High-power dual-rod Yb:YAG laser,J.Opt.Lett., 2000,25(11):805～807.
[4]J.Ausder Au,G.J.Spuhler et a1.,16.2W-average power from a diode -pumped femtosecond Yb:YAG thin disk laser,J.Opt.Lett., 2000,25(11):859～861.
[5]张丽哲,戴建明等,全固化可调谐Yb:YAG激光器,中国激光,2001,28(10):873～876.
[6]A.Giesen,M.Karszewski et a1.,Multiwatt-diode-pumped Yb:YAG thin disk laser continuously tunable between 1018 and 1053nm,J.Opt.Lett.,1991,20(7):713.
[7] F.Brenner,R.Paschotta et a1.,Widely tunable pulse durations from a passively mode-locked thin-disk Yb:YAG laser,J.Opt.Lett.,2001,26(6):379～381.
[8] D.S.Sumida,T.Y.Fan et al.,Effect of radiation trapping on fluores -cence lifetime and emtission cross section measurements in solid-state laser media,J.Opt.Lett.,19(17):1343～1346.
[9]杨培志,邓佩珍等,Yb:YAG晶体的光谱和激光性能,光学学报,1999,19(1):132～l35.
[10]徐晓东,赵志伟,宋平新等,高掺杂浓度Yb:YAG晶体的生长及光谱性能,中国激光,2004,31(8):955～958.
[11]Fan T Y,Heat generation in Nd:YAG and Yb:YAG,J.IEEE Quantum Electron,1993,QE-29:1457～1459.
[12]Ross,YAG laser operation by semieonductor laser pumping,J.Proc.IEEE,1968,56:196～197.
[13]Kruke W F,Chase L L,Ground-state depleted solid-state lasers prin -ciple,characteristic and scaling,J.Opt.,Quantum Electronics,1990,22:S1～S22.
[14]Lacovara P,Choi H K ,Wang C A et al., Room-temperature diode-pumped Yb:YAG laser,J.Opt.Lett.,1991,16[14]1089～1091.
[15]Deloach L D,Payne S A,Chaseetal L L,valuation of absorption and emission properties of Yb3+ doped crystals for laser applications,J.IEEE .Quant.Electron.,1993,QE-29(4):1179～1190.
[16]Marshall C D,Smith L K,Beachetal R J,Diode-pumped Yb:Sr5(PO4)3F laser performance,J.IEEE.Quant.Electron.,1996,QE-32(4):650～656.
[17]邱宏伟,杨培志,Yb:YAG激光晶体的高温退火和高浓度掺杂效应,J.中国激光,2000,20(3):339～443.
[18]Giesen A,Brauch U,Johannsen I et a1.,High-power near diffraction -limited and single-frequency operation of Yb:YAG thin disk laser, J.Opt.Soc.America.,1996,11～13.
[19]Karszewski M,Brauch U et a1.,100W TEM00 operation of Yb:YAG thin disc laser with high efficiency,J.Opt.Soc.Amer.,1998,19:125.
[20]Li Chao,Xu Zhen,Li Junlin et a1.,Diode pumped Yb:YAG thin disk laser achieves 16W CW output, J.Chinese Journal of Quantum Electroni -cs,2002,19(2):104-108.
[21]Jun Dong,Michael Bass,Dependence of the Yb3+ emission crosss section and lifetime on temperature and concentration in yttrium luminumg garnet,J.OPtieal Soeiety of America,2003,20(9),1975～1979.
[22]Laura D. DeLoach , StePhen A.Payne,Evaluation of Absorption and Emission Properties Yb3+ Dopede Crystals for Laser Applications,J. IEEE Quantuam Electronins,1993,19(4),1179～1191.
[23]Reinberg A R,Risenberg L A, Brown R M et al.,GaAs:Si LED Pumped Yb:doped YAG laser,Appl.Phys.Lett.,1971,19(1):11～13.
[24]Hongbin Yin,Peizhen Deng,Fuxi Gan et al.,Defects in Yb:YAG crys -tal,J.Appl.Phys.,1998,830:3825～3828.
[25]Jun Dong,Akira Shirakaw et al.,Efficient laser oseillation of Yb:Y3A15O12 single cryslal grown by temperature gradient techniqu -e.Appl.Phys.Lett.,2006,88:1615～1618.
[26]D.S.Sumida,H.Bruesselbach,R.W.Byren et al.,High-Power Yb:YAG rod oscillators and amplifiers,SPIE,1998,3265:100～103.
[27]C Stewen,K Contag et al.,A 1-kW CW thin disc laser ,J.IEEE.Quantum Election.,2000,6(4):650～657.
[28]J.Wallace,Commereial disk laser reaches 4-kW output,Laser Focus World,2004,19:122～126.
[29]Y.Kalisky,C.Labbe,K.Waiehm et al.,Passively Q-switched diode–Pumpe -d Yb:YAG laser using Cr4+-doped garnets,Opt.Mater,2002,19(4):403～407.
[30]T.Y.Fan,S.Klunk,GHenein,Diode-Pumped Q-switched Yb:YAG laser, OPt. Lett.,1993,18(6):423～427.
[31]D.S.Sumida,T.Y.Fan,A 50mJ per transversely diode pumped Yb:YAG laser at room temperature,J.CLEO.,1994:419～420.
[32]A Giesen,H Hugel et a1.,Scalable concept for Diode-pumped hig - en-power solid-state laers,J.Appl.Phy B.,1994,58(4):365～372.
[33]T S Rutherford,W M Tulloch,E K Gustafson et a1.,Ed-pumped quasi-three-level slab laser:design and power scalingf, J.IEEE . Quantum Electron.,2000,36(2):205～219.
[34]J.Dong,P.Deng,Y.Liu et al.,Passively Q-switched Yb:Y AG laser with Cr:YAG as the saturable absorber,J.Appl.Opt.,2001,40(24):4303～4307.
[35] E.C.Honea,R.J.Beach,S.C.Mitchell et al.,High-Power dual-rod Yb:YAG laser,Opt.Lett.,2000,25(11):805～900.
[36]Q.Liu,M.Gong,F.Lu et al.,520-W continuous-wave diode corner-pumped composite Yb:YAG slab laser,J.Opt.Lett.,2005,30(7):726～731.
[37]Masaki Tsunekane, Traian Dascalu, High-power, diode edge-pumped, single-crystal Yb:YAG /ceramic YAG composite microchip Yb:YAG laser for material processing,OSA/CLEO 2005.
[38]Mali Gong,Fuyuan Lu,Efficient corner-pumped Yb:YAG/YAG composite slab laser,J.Optical Society of America., 2006,45(16):3806～3810.
[39]施翔睿,石鹏,Yb:YAG薄片激光介质的温度效应,J.光学学报,2001,21(10):1268～1271.
[40]Farru Chou,An analysis of the temperature distribution in finite solid statelaser rods,J.IEEE Quantum Electron.,1988,24(11):2253～2264.
[41]杨鸿儒,左铁钏,全固态小型Yb:YAG激光器热效应及输出特性的研究,J.光子学报,2003,32(8):907～910.
[42]Sugiyama A,Fukuyama H et al.,Direct bonding of Ti:sapphire laser crystals,Appl.Opt.,1998,18:88～92.
[43]Sugiyama A,Fukuyama H et al.,Evaluations of bonded region in a direct bonded Ti:sapphire laser crystal,CLEO/Pacific Rim 2001,2001,WH3-3:Ⅱ460～Ⅱ461.
[44]Sugiyama A,Fukuyama H,et al.,Nd:YVO4 and YVO4 laser crystals Integration by a direct bonding technique,J.Proc.SPIE.,2002,4944:361～368.
[45]J. M. Eggleston, T. J. Kane, K. Kuhn et al., The slab geometry laser-part I: theory, IEEE, J. quantum electronics, 1984, 20(3), 289～301.
[46]吴家龙等,弹性力学,北京:高等教育出版社,2001:277～282.
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