高功率二极管泵浦激光模块特性研究
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摘要
二极管泵浦的固体激光器(DPSSL或者DPL)具有高效率、结构紧凑、工作稳定、寿命长和全固化等优点,在材料加工、军事、医疗、科研等领域已得到广泛应用,成为国际上新型固体激光器的发展热点。固体激光器中的热效应一直是激光技术研究中的一个重要课题,尤其是在大功率工作的情况下,热效应的影响尤为显著,严重降低了光束质量。引起光束质量下降的因素主要是热致双折射引起的双焦点和热致波前畸变,波前畸变主要包括球差和高阶像差。本论文针对热效应引起的双折射效应和波前畸变进行理论和实验研究。
论文建立了高功率二极管泵浦棒状Nd:YAG激光模块热透镜和热致球差效应的理论模型,得到了各因素与热透镜和热致球差的变化关系,为研究激光模块热效应提供了理论参考;开展了激光模块热致球差的实验研究,测量了侧泵浦重复频率脉冲Nd:YAG激光模块的热致球差,并对球差进行了补偿实验研究,为获得高功率高光束质量的激光器提供了实验参考。研究了侧泵浦重复频率脉冲Nd:YAG激光模块性能参数对其产生激光的影响,为评价激光模块的性能建立了基础。
对二极管激光器热效应的基本原理、以及热效应补偿技术国内外发展现状做了介绍,重点介绍了对热致双折射和双焦点、热致球差和高阶像差的补偿方法。
对侧泵浦的高功率二极管棒状Nd:YAG激光模块热透镜和热致球差效应进行了理论分析和数值模拟,得到了增益晶体截面的热分布,泵浦不均匀度δ与热透镜焦距和球差的关系,泵浦功率、晶体长度与球差的关系,以及激光晶体物理参数与热透镜焦距和球差的关系。
介绍了重复频率脉冲Nd:YAG激光模块球差的测量原理、测量系统和测量实验结果,分析了球差随晶体冷却温度的变化情况;介绍了球差的补偿原理和补偿实验,分析了补偿前后球差随工作电流的变化情况,总结了球差补偿对光束质量β因子的影响;对球差补偿镜在MOPA系统中的效果进行了验证实验,达到了较好的效果。
基于激光模块在谐振腔和作为放大器使用时输出功率、光束质量两方面的考虑,研究了侧泵浦重复频率脉冲Nd:YAG激光模块性能参数对其产生激光的影响。
Diode-pumped solid-state laser (DPSSL, DPL) with the advantages of high efficiency, compact structure, stability, long life and all-solid, has been widely used in the material processing, military, medical, scientific and other fields, and has become a hot spot of novel solid-state laser development worldwide. Thermal effect of Solid-state laser has been an important research topic in laser technology. Especially in the high-power pumping, the thermal effect seriously degrades the beam quality. The main beam-quality degradation factors are birefringence-induced bifocusing and thermally induced wavefront (WF) deformation. Wavefront aberration mainly includes spherical aberration and higher-order aberrations. In this thesis, a series of theoretical and experimental researches on thermally-induced birefringence and wavefront (WF) deformation were studied.
The theoretical model of thermally-induced thermal lensing and spherical aberration of high-power diode-pumped rod Nd: YAG laser module was established. It was obtained the relationship between the thermally-induced thermal lensing and spherical aberration with various changing factors, providing the theoretical reference for research on thermal effect of laser module. The experimental research on thermally-induced spherical aberration of laser module was developed. Thermally-induced spherical aberration of repeat pulse Nd:YAG laser module was measured and compensated, providing the experimental reference to the laser with high power and high beam quality. The effect of the performance parameters of side-pumped repeat pulse Nd:YAG laser module on generated laser was studied, providing the foundation for evaluating the performance of laser module.
Basic theory of thermal effect of diode-pumped laser and the development of compensation for thermal effect around the world was introduced, with emphasis on the compensation method of thermally-induced birefringence, bifocusing, spherical aberration and high order aberrations.
Thermal lensing and spherical aberration of side-pumped high-power diode Nd: YAG laser module was theoretically analyzed and numerically simulated. It was achieved the heat distribution of gain crystal profile, the relationship between pumping inhomogeneityδand thermal lensing length as well as spherical aberration, the relationship between pumping power as well as crystal length and spherical aberration, and the relationship between laser crystal physics parameters and thermal lensing length as well as spherical aberration.
Measurement theory, system and experimental result of spherical aberration of repeat pulse Nd:YAG laser module was introduced in this thesis. Meanwhile, the change between spherical aberration and crystal cooling temperature was analyzed. Compensation theory and experiment of spherical aberration was described in detail. Moreover, the change between spherical aberration and operating current in the changes of compensation was analyzed, Finally, the influence of spherical aberration on beam quality factorβwas summarized. A fine accomplishment was achieved by the experimental study on the effect of spherical aberration compensator in MOPA system.
Furthermore, considering the output power and beam quality of the laser module in resnator and as an amplifier, the effect of the performance parameters of side-pumped repeat pulse Nd:YAG laser module on generated laser was studied.
论文建立了高功率二极管泵浦棒状Nd:YAG激光模块热透镜和热致球差效应的理论模型,得到了各因素与热透镜和热致球差的变化关系,为研究激光模块热效应提供了理论参考;开展了激光模块热致球差的实验研究,测量了侧泵浦重复频率脉冲Nd:YAG激光模块的热致球差,并对球差进行了补偿实验研究,为获得高功率高光束质量的激光器提供了实验参考。研究了侧泵浦重复频率脉冲Nd:YAG激光模块性能参数对其产生激光的影响,为评价激光模块的性能建立了基础。
对二极管激光器热效应的基本原理、以及热效应补偿技术国内外发展现状做了介绍,重点介绍了对热致双折射和双焦点、热致球差和高阶像差的补偿方法。
对侧泵浦的高功率二极管棒状Nd:YAG激光模块热透镜和热致球差效应进行了理论分析和数值模拟,得到了增益晶体截面的热分布,泵浦不均匀度δ与热透镜焦距和球差的关系,泵浦功率、晶体长度与球差的关系,以及激光晶体物理参数与热透镜焦距和球差的关系。
介绍了重复频率脉冲Nd:YAG激光模块球差的测量原理、测量系统和测量实验结果,分析了球差随晶体冷却温度的变化情况;介绍了球差的补偿原理和补偿实验,分析了补偿前后球差随工作电流的变化情况,总结了球差补偿对光束质量β因子的影响;对球差补偿镜在MOPA系统中的效果进行了验证实验,达到了较好的效果。
基于激光模块在谐振腔和作为放大器使用时输出功率、光束质量两方面的考虑,研究了侧泵浦重复频率脉冲Nd:YAG激光模块性能参数对其产生激光的影响。
Diode-pumped solid-state laser (DPSSL, DPL) with the advantages of high efficiency, compact structure, stability, long life and all-solid, has been widely used in the material processing, military, medical, scientific and other fields, and has become a hot spot of novel solid-state laser development worldwide. Thermal effect of Solid-state laser has been an important research topic in laser technology. Especially in the high-power pumping, the thermal effect seriously degrades the beam quality. The main beam-quality degradation factors are birefringence-induced bifocusing and thermally induced wavefront (WF) deformation. Wavefront aberration mainly includes spherical aberration and higher-order aberrations. In this thesis, a series of theoretical and experimental researches on thermally-induced birefringence and wavefront (WF) deformation were studied.
The theoretical model of thermally-induced thermal lensing and spherical aberration of high-power diode-pumped rod Nd: YAG laser module was established. It was obtained the relationship between the thermally-induced thermal lensing and spherical aberration with various changing factors, providing the theoretical reference for research on thermal effect of laser module. The experimental research on thermally-induced spherical aberration of laser module was developed. Thermally-induced spherical aberration of repeat pulse Nd:YAG laser module was measured and compensated, providing the experimental reference to the laser with high power and high beam quality. The effect of the performance parameters of side-pumped repeat pulse Nd:YAG laser module on generated laser was studied, providing the foundation for evaluating the performance of laser module.
Basic theory of thermal effect of diode-pumped laser and the development of compensation for thermal effect around the world was introduced, with emphasis on the compensation method of thermally-induced birefringence, bifocusing, spherical aberration and high order aberrations.
Thermal lensing and spherical aberration of side-pumped high-power diode Nd: YAG laser module was theoretically analyzed and numerically simulated. It was achieved the heat distribution of gain crystal profile, the relationship between pumping inhomogeneityδand thermal lensing length as well as spherical aberration, the relationship between pumping power as well as crystal length and spherical aberration, and the relationship between laser crystal physics parameters and thermal lensing length as well as spherical aberration.
Measurement theory, system and experimental result of spherical aberration of repeat pulse Nd:YAG laser module was introduced in this thesis. Meanwhile, the change between spherical aberration and crystal cooling temperature was analyzed. Compensation theory and experiment of spherical aberration was described in detail. Moreover, the change between spherical aberration and operating current in the changes of compensation was analyzed, Finally, the influence of spherical aberration on beam quality factorβwas summarized. A fine accomplishment was achieved by the experimental study on the effect of spherical aberration compensator in MOPA system.
Furthermore, considering the output power and beam quality of the laser module in resnator and as an amplifier, the effect of the performance parameters of side-pumped repeat pulse Nd:YAG laser module on generated laser was studied.
引文
1 吕百达编著.固体激光器件[M].北京邮电大学出版社,2002.
2 M.D.Rotter,C.Brent Dane.Solid-state Heat-capacity-laser Review.SSDLTR 2002 Technical Digest.
3 C.Brent Dane.World's Most Powerful Solid-State Laser.2002.
4 W.克希耐尔,孙文江泽文程国详译.固体激光工程[M].科学出版社,2002.
5 裴正平,唐淳,涂波,等.Nd:YAG薄片激光器热致波前畸变[J].强激光与粒子束,2006,18(10):1615-1618.
6 I.Moshe,S.Jackel,A.Meir,Y.Lumer,E.Leibush.2 kW,M~2<10 radially polarized beams from aberrationcompensated rod-based Nd:YAG lasers[J].Opt.Lett.2007,32:47-49.
7 T.Moser,M.A.Ahmed,F.PigeonLaser.Generation of radially polarized beams in Nd:YAG lasers with polarization selective mirrors[J].Phys.Lett.1,2004,5:234-236.
8 Ze'ev Bomzon,Gabriel Biener,Vladimir Kleiner,Erez Hasman.Radially and azimuthally polarized beams generated by space-variant dielectric subwavelength gratings[J].Opt.Lett.2002,27:285.
9 I.Moshe,S.Jackel,and A.Meir,Production of radially or azimuthally polarized beams insolid-state lasers and the elimination of thermally induced birefringence effects[J].Opt.Lett.2003,28:807.
10 Eyal Leibush,Steven Jackel,Sharon Goldring,Inon Moshe,Yitshak Tzuk,Avi Meir,Elimination of spherical aberration in multi-kW,Nd:YAG,rod pump-chambers by pump-distribution control[J].2005 Optical Society of America.
11 A.Montmerle Bonnefois,M.Gilbert,P-Y Thro,D.Farcage,J-M Weulersse,Novel Method to Improve the Performance of Nd:YAG High-power,Low Divergence Lasers Using a Passive Compensation of the Spherical Aberration inside the Resonator[J].Proceedings of SPIE Vol.5707
12 唐淳.高亮度高平均功率固体激光器技术评述[J].量子电子学报,2005,22(4):488-496.
13 N.Hodgson,H.Weber.Influence of spherical aberration of the active medium on the performance of Nd:YAG lasers[J].IEEE J.Quantum Electron.1993,29(9):2497.
14 N. Hodgson, H. Weber, Optical Resonators, Springer, Berlin, 1997.
15 J.D. Foster, L.M. Osterink. Thermal effects in a Nd:YAG laser[ J]. Appl. Phys. 1970,41 (9): 3656.
16 A. Montmerle Bonnefois, M. Gilbert, P.-Y. Thro, J.-M. Weulersse. Thermal lensing and spherical aberration in high-power transversally pumped laser rods[J]. Optics Communications, 2006, 259: 223-235.
17 R. Wynne, J.L. Daneu, T.Y. Fan. Thermal coefficients of the expansion and refractive index in YAG[J]. Appl. Opt. 1999, 38(15): 3282.
18 I. Moshe, S. Jackel, A. Meir. Correction of spherical and azimuthal aberrations in radially polarized beams from strongly pumped laser rods[J]. Appl. Opt. 2005, 44: 7823.
19 S. Goldring, R. Lavi, A. Tal, E. Lebiush, Y. Tzuk, S. Jackel, IEEE J.Quantum Electron. 2004, 40(4): 384.
20 T.Y Fan. Heat generation in Nd:YAG and Yb:YAG[J]. IEEE J. Quantum Electron. 1993,29(6): 1457.
21 D.C. Brown. Nonlinear Thermal Distortion in YAG Rod Amplifiers[J]. IEEE J. Quantum Electron. 1998, 34(12): 2383.
22 苏毅,万敏．高能激光系统[M]．北京：国防工业出版社,2004．(Su Y, Wan M. High energy laser. Beijing: National Defence Industry Press, 2004).
23 Virendra N. Mahajan. Zernike polynomials and aberration balancing[J]. Proc. of SPIE Vol. 5173 17.
24 I. Moshe and S. Jackel. Influence of birefringence induced bifocusing on optical beams[J]. Opt. Soc. Am. B, 2005, 22: 1228-1235.
25 A. E. Siegman. Analysis of laser beam quality degradation caused by quartic phase aberrations[J]. Appl. Opt. 1993, 32: 5893-5901.
26 S. Seidel, A. Sehimnaeher, G. Mann, Nursianni, T. Resbeek. Optimize resonators for high-average-power, high brightness Nd:YAG lasers with birefringence compensation[J]. Proc. SPIE, 1998, 3267: 214-225.
27 V. Magni. Resonators for solid-state lasers with large-volume fundamental mode and high alignment stability[J] .Appl. Opt, 1986, 25: 107-117.
2 M.D.Rotter,C.Brent Dane.Solid-state Heat-capacity-laser Review.SSDLTR 2002 Technical Digest.
3 C.Brent Dane.World's Most Powerful Solid-State Laser.2002.
4 W.克希耐尔,孙文江泽文程国详译.固体激光工程[M].科学出版社,2002.
5 裴正平,唐淳,涂波,等.Nd:YAG薄片激光器热致波前畸变[J].强激光与粒子束,2006,18(10):1615-1618.
6 I.Moshe,S.Jackel,A.Meir,Y.Lumer,E.Leibush.2 kW,M~2<10 radially polarized beams from aberrationcompensated rod-based Nd:YAG lasers[J].Opt.Lett.2007,32:47-49.
7 T.Moser,M.A.Ahmed,F.PigeonLaser.Generation of radially polarized beams in Nd:YAG lasers with polarization selective mirrors[J].Phys.Lett.1,2004,5:234-236.
8 Ze'ev Bomzon,Gabriel Biener,Vladimir Kleiner,Erez Hasman.Radially and azimuthally polarized beams generated by space-variant dielectric subwavelength gratings[J].Opt.Lett.2002,27:285.
9 I.Moshe,S.Jackel,and A.Meir,Production of radially or azimuthally polarized beams insolid-state lasers and the elimination of thermally induced birefringence effects[J].Opt.Lett.2003,28:807.
10 Eyal Leibush,Steven Jackel,Sharon Goldring,Inon Moshe,Yitshak Tzuk,Avi Meir,Elimination of spherical aberration in multi-kW,Nd:YAG,rod pump-chambers by pump-distribution control[J].2005 Optical Society of America.
11 A.Montmerle Bonnefois,M.Gilbert,P-Y Thro,D.Farcage,J-M Weulersse,Novel Method to Improve the Performance of Nd:YAG High-power,Low Divergence Lasers Using a Passive Compensation of the Spherical Aberration inside the Resonator[J].Proceedings of SPIE Vol.5707
12 唐淳.高亮度高平均功率固体激光器技术评述[J].量子电子学报,2005,22(4):488-496.
13 N.Hodgson,H.Weber.Influence of spherical aberration of the active medium on the performance of Nd:YAG lasers[J].IEEE J.Quantum Electron.1993,29(9):2497.
14 N. Hodgson, H. Weber, Optical Resonators, Springer, Berlin, 1997.
15 J.D. Foster, L.M. Osterink. Thermal effects in a Nd:YAG laser[ J]. Appl. Phys. 1970,41 (9): 3656.
16 A. Montmerle Bonnefois, M. Gilbert, P.-Y. Thro, J.-M. Weulersse. Thermal lensing and spherical aberration in high-power transversally pumped laser rods[J]. Optics Communications, 2006, 259: 223-235.
17 R. Wynne, J.L. Daneu, T.Y. Fan. Thermal coefficients of the expansion and refractive index in YAG[J]. Appl. Opt. 1999, 38(15): 3282.
18 I. Moshe, S. Jackel, A. Meir. Correction of spherical and azimuthal aberrations in radially polarized beams from strongly pumped laser rods[J]. Appl. Opt. 2005, 44: 7823.
19 S. Goldring, R. Lavi, A. Tal, E. Lebiush, Y. Tzuk, S. Jackel, IEEE J.Quantum Electron. 2004, 40(4): 384.
20 T.Y Fan. Heat generation in Nd:YAG and Yb:YAG[J]. IEEE J. Quantum Electron. 1993,29(6): 1457.
21 D.C. Brown. Nonlinear Thermal Distortion in YAG Rod Amplifiers[J]. IEEE J. Quantum Electron. 1998, 34(12): 2383.
22 苏毅,万敏．高能激光系统[M]．北京：国防工业出版社,2004．(Su Y, Wan M. High energy laser. Beijing: National Defence Industry Press, 2004).
23 Virendra N. Mahajan. Zernike polynomials and aberration balancing[J]. Proc. of SPIE Vol. 5173 17.
24 I. Moshe and S. Jackel. Influence of birefringence induced bifocusing on optical beams[J]. Opt. Soc. Am. B, 2005, 22: 1228-1235.
25 A. E. Siegman. Analysis of laser beam quality degradation caused by quartic phase aberrations[J]. Appl. Opt. 1993, 32: 5893-5901.
26 S. Seidel, A. Sehimnaeher, G. Mann, Nursianni, T. Resbeek. Optimize resonators for high-average-power, high brightness Nd:YAG lasers with birefringence compensation[J]. Proc. SPIE, 1998, 3267: 214-225.
27 V. Magni. Resonators for solid-state lasers with large-volume fundamental mode and high alignment stability[J] .Appl. Opt, 1986, 25: 107-117.