二极管侧面泵浦的Nd：YAG薄片激光器
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摘要
二极管泵浦的薄片激光器相比于传统的全固态激光器有两个明显的优势,一是薄片激光器增益介质的热流平行于激光腔腔轴,近一维的热流分布导致腔内的热透镜效应大大减弱,热应力诱导双折射可忽略;二是薄片激光器增益介质冷却表面大,增益介质薄片的热耗散功率大大提高。使得薄片激光器在获得高功率激光输出的同时保持高效率和高光束质量,成为近二十年来全固态激光器的重要进展之一。
薄片激光器有端面泵浦与侧面泵浦两种方式,端面泵浦方式采用光纤耦合输出、或聚焦于石英棒输出的泵浦光,产生均匀分布的光束包络,从端面泵浦薄片增益介质,未被吸收的泵浦光经多次反射后,可实现90%以上的泵浦吸收。侧面泵浦方式是直接将泵浦光从薄片增益介质的几个侧面传输入。比较两种泵浦方式,侧面泵浦不仅光学系统结构简化、泵浦光无需光纤耦合,有利于激光器整体效率的提高,而且可通过增大介质薄片的面积,增加通光口径,避免由于口径限制而引起过大的热负荷,进而降低晶体单位面积内的热耗散功率密度,进一步发挥薄片激光器的潜力。
本文通过二极管侧面泵浦薄片激光器晶体内光分布的数值模型计算了晶体内光斑实现均匀分布情况下的Nd:YAG晶体尺寸,然后将Nd:YAG晶体与非掺杂的YAG晶体热键合,再将热键合晶体镀膜,铟焊于铜热沉上,最后将激光器组装。为了实现高的功率及好的光束质量的激光输出,我们还设计了不同的实验,对各种参数进行优化,同时还进行了相关的理论研究。获得了光光转换效率为33.5%,峰值功率为230W,光束参数乘积为21.6 mm*mrad的激光输出。
Comparing with traditional all-solid laser, thin-disk laser has two significant advantages. One advantage is the direction of cooling flow is the same with cavity resonant oscillation of light, making cooling flow similar to one-dimensional heat distribution, which effectively reduces the thermal lens effect; the other is the large cooling area of gain medium for disc-laser, making the heat dissipation power density of the material being pumped per area very small. These two advantages make the side-pumped thin-disk laser have very high power and good beam quality.
Disk laser has two kind of pump style, side-pumping and end-pumping. The end-pump mode use fiber-coupled beam, generating homogeneous beam distribution. After multiple reflections, about 90% pumping light can be absorbed. The side-pump mode is making the pumped light into the crystal directly. Compared to end-pump mode, the side-pump mode not only has very simple structure, no coupled fiber and high efficiency, but also can reduce the heat dissipation power density of the material per area by enlarging the area of gain medium, which highlight the development potential of disc-laser.
By numerical simulation of the light distribution in crystal, we achieve the crystal size under the situation of uniform distribution of light. Then after bonding, film coating of the bonded crystal, and soldering on the copper heat sink, we finally realize the side-pumped thin disk-laser. Besides, we designed different experiments, for optimizing the various parameters, and at the same time, related theoretical research is done. Finally, we achieved the laser output with 33.5% of opt.-opt. effect, 230W of peak power and 21.6 mm*mrad of the beam parameter product.
薄片激光器有端面泵浦与侧面泵浦两种方式,端面泵浦方式采用光纤耦合输出、或聚焦于石英棒输出的泵浦光,产生均匀分布的光束包络,从端面泵浦薄片增益介质,未被吸收的泵浦光经多次反射后,可实现90%以上的泵浦吸收。侧面泵浦方式是直接将泵浦光从薄片增益介质的几个侧面传输入。比较两种泵浦方式,侧面泵浦不仅光学系统结构简化、泵浦光无需光纤耦合,有利于激光器整体效率的提高,而且可通过增大介质薄片的面积,增加通光口径,避免由于口径限制而引起过大的热负荷,进而降低晶体单位面积内的热耗散功率密度,进一步发挥薄片激光器的潜力。
本文通过二极管侧面泵浦薄片激光器晶体内光分布的数值模型计算了晶体内光斑实现均匀分布情况下的Nd:YAG晶体尺寸,然后将Nd:YAG晶体与非掺杂的YAG晶体热键合,再将热键合晶体镀膜,铟焊于铜热沉上,最后将激光器组装。为了实现高的功率及好的光束质量的激光输出,我们还设计了不同的实验,对各种参数进行优化,同时还进行了相关的理论研究。获得了光光转换效率为33.5%,峰值功率为230W,光束参数乘积为21.6 mm*mrad的激光输出。
Comparing with traditional all-solid laser, thin-disk laser has two significant advantages. One advantage is the direction of cooling flow is the same with cavity resonant oscillation of light, making cooling flow similar to one-dimensional heat distribution, which effectively reduces the thermal lens effect; the other is the large cooling area of gain medium for disc-laser, making the heat dissipation power density of the material being pumped per area very small. These two advantages make the side-pumped thin-disk laser have very high power and good beam quality.
Disk laser has two kind of pump style, side-pumping and end-pumping. The end-pump mode use fiber-coupled beam, generating homogeneous beam distribution. After multiple reflections, about 90% pumping light can be absorbed. The side-pump mode is making the pumped light into the crystal directly. Compared to end-pump mode, the side-pump mode not only has very simple structure, no coupled fiber and high efficiency, but also can reduce the heat dissipation power density of the material per area by enlarging the area of gain medium, which highlight the development potential of disc-laser.
By numerical simulation of the light distribution in crystal, we achieve the crystal size under the situation of uniform distribution of light. Then after bonding, film coating of the bonded crystal, and soldering on the copper heat sink, we finally realize the side-pumped thin disk-laser. Besides, we designed different experiments, for optimizing the various parameters, and at the same time, related theoretical research is done. Finally, we achieved the laser output with 33.5% of opt.-opt. effect, 230W of peak power and 21.6 mm*mrad of the beam parameter product.
引文
1李晋闽,高平均功率全固态激光器发展现状、趋势及应用,激光与光电子学进展,2008,45(7):16~27
2吕百达,马虹,二极管泵浦固体激光器研究的一些新进展,激光与红外,30(2):67~70.
3杜秀兰,吴峰,固体激光器的灯泵浦和二极管泵浦方式比较,应用光学,2004,25(3):37~40 .
4郑权,赵岭,钱龙生,大功率二极管泵浦固体激光器的应用和发展,光学精密工程,2001,19(1):6~9.
5王成,方志丹,李晓英等,激光二极管泵浦全固体激光器,长春光学精密机械学院学报,2001,24(1):56~58.
6 R.Newman,Excitation of the Nd3+fluorescence in CaWO4 by recombination radiation in GaAs,J.Appl.Phys,1963,34:437~438.
7 L.J.Rosenkkrantz,GaAs diode-pumped Nd:YAG lase,J.Appl.Phys.,1972,43:4603~4605
8 A. Larsson, M.Mittlestein,Y.Arakawa,et al.,High efficiency broad-area single quantum well lasers with narrow single-lobed far-field patterns prepared bimolecular beam epitaxy,Electon.Lett,1986,22:79~81.
9 Thomas J.Kane,Alan C.Nilsson,Robert L.Byer,Frequency stability and offset locking of a laser-diode-pumped Nd:YAG monolithic nonplanar ring oscillator,Opt.Lett,1987,12:175~177.
10 Randall J.St.Pierre,David W.Mordaunt,Hagop Injeyan et al. Diode Array Pumped Kilowatt Laser,Journal OF Selected Topics in Quantum Electronics,1997,3(1):53~58.
11 Project yields a pair of 3.3KW solid-state lasers,Laser Focus Word,1999,35(7):38~40.
12先进固体激光会议报道,激光与光电子学进展,2001,3:58.
13 C.Stewen, K.Contag, M.Larionov, et al, A 1-kW CW thin disc laser, Quantum Electronics. 2000, 6:650~657.
14 Alan J.Kemp, Gareth J.Valentine, David Burns, Progress towards high-power,high-brightness neodymium-basedthin-disklasers,Quantum Electronics,2004,28:305~344.
15 A.Giesen, H.Hugel, A.Voss, K.Wittig, et al, Scalable concept for diode pumped high-power solid-state-laser, Appl. Phys. 1994, 58:365~372.
16 A. Giesen, Results and scaling laws of thin disk lasers Hanna J. Hoffman, Proc.of SPIE Vol. 5332, WA, Solid State Lasers XIII: Technology and Devices, 2004:212~227.
17姚震宇,蒋建锋,二极管泵浦Nd :YAG薄片激光器技术研究,强激光与粒子束,2005,(17):15~18.
18 Adolf Giesen.High-power thin-disc laser.Opt.l Soci.Amer.,2007,MA1
19姚震宇,蒋建峰,涂波等.1.5 kW激光二极管抽运Nd:YAG薄片激光器.中国激光,2007,34(1):37~40
20 Vetrovec John. Conceptual design of a 100kW-class solid state laser, Fourteenth Annual on Solid-State and Diode Laser Technology Review, 2001:100~103.
21 Vetrovec John. Active mirror amplifier for high-average power, SPIE 2001,4270:45~55.
22 Vetrovec John. Ultrahigh-Average Power Solid-State Laser, SPIE 2002, 4760: invited paper.
23 John Vetrovecc, Rashmi Shah, Tom Endo, Andrea Koumvakalis, Progress in theDevelopment of Solid-State Disk Laser, SPIE LASE 2004 Conference, San Jose, CA, 2004(1):25~30,.
24 T.Dascalu, N.Pavel, T.Tair. 90 W continuous-wave diode edge-pumped microchip composite Yb: Y3Al5O12 laser, Applied Physics Letters, 2003, 83(20): 4086~4088
25 Masaki Tsunekane, Traian Dascalu, and Takunori Taira,High-power, diode edge-pumped, single-crystal Yb:YAG /ceramic YAG composite microchip Yb:YAG laser for material processing, Optical Society of America ,2005
26 Masaki Tsunekane, Takunori Taira, 300W continuous-wave operation of a diode edge-pumped, hybrid composite Yb:YAG microchip laser, Optics Letters, 2006. 31(13):1~3
27 Masaki Tsunekanea_ and Takunori Taira,High-power operation of diode edge-pumped, composite all-ceramicYb:Y3Al5O12 microchip laser,Applied Physics letters,2007,(90):1~3
28柳强,巩马理等,边缘抽运复合Yb:YAG/YAG薄片激光器设计与功率扩展,物理学报,2004, 53(7):2159~2164.
29张申金周寿桓唐晓军等,二极管侧面泵浦圆片激光器增益介质内泵浦光分布,红外与激光工程, 2007,36 (4): 505-508
30张申金周寿桓唐晓军等,激光二极管阵列侧面对称抽运薄片激光器,中国激光, 2008,35(2):168~172
31 John Vetrovec, Materials for High-Average Power Solid-State Laser, SPIE,2003,( 4968): 87~96
32李小莉,两种半导体泵浦的固体激光器件的应用基础研究,硕士学位论文,中国科学院上海光学精密机械研究所,2000:2~3
33 T. Y. Fan,Heat Generation in Nd : YAG and Yb : YAG, IEEE JOURNAL OF QUANTUM ELECTRONICS.1993,29(6):1457~1459
34 Giesen. A, Huegel. H, Diode-pumped high power solid state laser: concept and first results with Yb:YAG, Advanced Solid State Lasers (ASSL).1994,(20):91~94
35吕百达,固体激光器件,北京邮电大学出版社,2002:43~46
36庞恺,李强等,二极管泵浦薄片激光器的最新进展,应用激光,2008,28(2):155~159
37庞恺,李强等,二极管侧面泵浦薄片激光器泵浦均匀性分析,强激光与粒子束,2008, 20(8):1243~1248
38王春雨、陆雨田等,LD侧面泵浦固体激光器泵浦光分布模拟,光子学报,2007,36(6):961~965
39蒋向东,张怀武,黄祥成等,激光高反射膜的研究,应用光学,2003, 24,(1)
40沈军,王珊等,多层高反膜的理论设计与光学特性分析,同济大学学报,2005,33(5)
41袁景梅,汤兆胜,易葵等,高折射率材料吸收特性193nmHfO2/SiO2,Y2O3/SiO2多层膜反射特性的影响,中国激光,2004
42徐则川,李义兵等,金属-介质多层膜的光学特性,华中理工大学学报.1997,25(1)
43姚月松,樊祥,李菲等,金属膜材料后向反射1.06微米激光实验测试与分析,光电技术应用,2007(2): 1673~1255
44唐婷婷,王锐,刘刚明等,808nm激光器端面镀膜技术,半导体光电,2006,4(27)
45王致远,刘方楠等,半导体激光器腔面镀膜技术研究进展,中国材料科技与设备,2007,(5)
46杨淑兰,黎俊杰等,声光器件的关键技术-高真空铟压焊,光电工程,1992 12(19)
47谭满清,林永昌等,过渡金属超薄膜的光学性质及其应用,中国激光,1997,24(4)
48姚建铨、徐德刚著,全固态激光及非线性光学频率变换技术[M],北京:科学出版社,2006:185~206
49 Thomas J. Kane, John M.Eggleston ,Robert L.Byer, et al ,The Slab Geometry Laser-Part II: Thermal Effects in a Finite Slab,Journal of Quantum Electronics, 1985, 21(20), 1195~1210
50 Robert L.Byer,Martin M. Fejer,David A. B. Miller,An Edge-pumped Yb:YAG Slab Laser and Phased Array Resonator,The Dissertation of doctor,s Degree ,Bell Howell and Learning Company,12~92
2吕百达,马虹,二极管泵浦固体激光器研究的一些新进展,激光与红外,30(2):67~70.
3杜秀兰,吴峰,固体激光器的灯泵浦和二极管泵浦方式比较,应用光学,2004,25(3):37~40 .
4郑权,赵岭,钱龙生,大功率二极管泵浦固体激光器的应用和发展,光学精密工程,2001,19(1):6~9.
5王成,方志丹,李晓英等,激光二极管泵浦全固体激光器,长春光学精密机械学院学报,2001,24(1):56~58.
6 R.Newman,Excitation of the Nd3+fluorescence in CaWO4 by recombination radiation in GaAs,J.Appl.Phys,1963,34:437~438.
7 L.J.Rosenkkrantz,GaAs diode-pumped Nd:YAG lase,J.Appl.Phys.,1972,43:4603~4605
8 A. Larsson, M.Mittlestein,Y.Arakawa,et al.,High efficiency broad-area single quantum well lasers with narrow single-lobed far-field patterns prepared bimolecular beam epitaxy,Electon.Lett,1986,22:79~81.
9 Thomas J.Kane,Alan C.Nilsson,Robert L.Byer,Frequency stability and offset locking of a laser-diode-pumped Nd:YAG monolithic nonplanar ring oscillator,Opt.Lett,1987,12:175~177.
10 Randall J.St.Pierre,David W.Mordaunt,Hagop Injeyan et al. Diode Array Pumped Kilowatt Laser,Journal OF Selected Topics in Quantum Electronics,1997,3(1):53~58.
11 Project yields a pair of 3.3KW solid-state lasers,Laser Focus Word,1999,35(7):38~40.
12先进固体激光会议报道,激光与光电子学进展,2001,3:58.
13 C.Stewen, K.Contag, M.Larionov, et al, A 1-kW CW thin disc laser, Quantum Electronics. 2000, 6:650~657.
14 Alan J.Kemp, Gareth J.Valentine, David Burns, Progress towards high-power,high-brightness neodymium-basedthin-disklasers,Quantum Electronics,2004,28:305~344.
15 A.Giesen, H.Hugel, A.Voss, K.Wittig, et al, Scalable concept for diode pumped high-power solid-state-laser, Appl. Phys. 1994, 58:365~372.
16 A. Giesen, Results and scaling laws of thin disk lasers Hanna J. Hoffman, Proc.of SPIE Vol. 5332, WA, Solid State Lasers XIII: Technology and Devices, 2004:212~227.
17姚震宇,蒋建锋,二极管泵浦Nd :YAG薄片激光器技术研究,强激光与粒子束,2005,(17):15~18.
18 Adolf Giesen.High-power thin-disc laser.Opt.l Soci.Amer.,2007,MA1
19姚震宇,蒋建峰,涂波等.1.5 kW激光二极管抽运Nd:YAG薄片激光器.中国激光,2007,34(1):37~40
20 Vetrovec John. Conceptual design of a 100kW-class solid state laser, Fourteenth Annual on Solid-State and Diode Laser Technology Review, 2001:100~103.
21 Vetrovec John. Active mirror amplifier for high-average power, SPIE 2001,4270:45~55.
22 Vetrovec John. Ultrahigh-Average Power Solid-State Laser, SPIE 2002, 4760: invited paper.
23 John Vetrovecc, Rashmi Shah, Tom Endo, Andrea Koumvakalis, Progress in theDevelopment of Solid-State Disk Laser, SPIE LASE 2004 Conference, San Jose, CA, 2004(1):25~30,.
24 T.Dascalu, N.Pavel, T.Tair. 90 W continuous-wave diode edge-pumped microchip composite Yb: Y3Al5O12 laser, Applied Physics Letters, 2003, 83(20): 4086~4088
25 Masaki Tsunekane, Traian Dascalu, and Takunori Taira,High-power, diode edge-pumped, single-crystal Yb:YAG /ceramic YAG composite microchip Yb:YAG laser for material processing, Optical Society of America ,2005
26 Masaki Tsunekane, Takunori Taira, 300W continuous-wave operation of a diode edge-pumped, hybrid composite Yb:YAG microchip laser, Optics Letters, 2006. 31(13):1~3
27 Masaki Tsunekanea_ and Takunori Taira,High-power operation of diode edge-pumped, composite all-ceramicYb:Y3Al5O12 microchip laser,Applied Physics letters,2007,(90):1~3
28柳强,巩马理等,边缘抽运复合Yb:YAG/YAG薄片激光器设计与功率扩展,物理学报,2004, 53(7):2159~2164.
29张申金周寿桓唐晓军等,二极管侧面泵浦圆片激光器增益介质内泵浦光分布,红外与激光工程, 2007,36 (4): 505-508
30张申金周寿桓唐晓军等,激光二极管阵列侧面对称抽运薄片激光器,中国激光, 2008,35(2):168~172
31 John Vetrovec, Materials for High-Average Power Solid-State Laser, SPIE,2003,( 4968): 87~96
32李小莉,两种半导体泵浦的固体激光器件的应用基础研究,硕士学位论文,中国科学院上海光学精密机械研究所,2000:2~3
33 T. Y. Fan,Heat Generation in Nd : YAG and Yb : YAG, IEEE JOURNAL OF QUANTUM ELECTRONICS.1993,29(6):1457~1459
34 Giesen. A, Huegel. H, Diode-pumped high power solid state laser: concept and first results with Yb:YAG, Advanced Solid State Lasers (ASSL).1994,(20):91~94
35吕百达,固体激光器件,北京邮电大学出版社,2002:43~46
36庞恺,李强等,二极管泵浦薄片激光器的最新进展,应用激光,2008,28(2):155~159
37庞恺,李强等,二极管侧面泵浦薄片激光器泵浦均匀性分析,强激光与粒子束,2008, 20(8):1243~1248
38王春雨、陆雨田等,LD侧面泵浦固体激光器泵浦光分布模拟,光子学报,2007,36(6):961~965
39蒋向东,张怀武,黄祥成等,激光高反射膜的研究,应用光学,2003, 24,(1)
40沈军,王珊等,多层高反膜的理论设计与光学特性分析,同济大学学报,2005,33(5)
41袁景梅,汤兆胜,易葵等,高折射率材料吸收特性193nmHfO2/SiO2,Y2O3/SiO2多层膜反射特性的影响,中国激光,2004
42徐则川,李义兵等,金属-介质多层膜的光学特性,华中理工大学学报.1997,25(1)
43姚月松,樊祥,李菲等,金属膜材料后向反射1.06微米激光实验测试与分析,光电技术应用,2007(2): 1673~1255
44唐婷婷,王锐,刘刚明等,808nm激光器端面镀膜技术,半导体光电,2006,4(27)
45王致远,刘方楠等,半导体激光器腔面镀膜技术研究进展,中国材料科技与设备,2007,(5)
46杨淑兰,黎俊杰等,声光器件的关键技术-高真空铟压焊,光电工程,1992 12(19)
47谭满清,林永昌等,过渡金属超薄膜的光学性质及其应用,中国激光,1997,24(4)
48姚建铨、徐德刚著,全固态激光及非线性光学频率变换技术[M],北京:科学出版社,2006:185~206
49 Thomas J. Kane, John M.Eggleston ,Robert L.Byer, et al ,The Slab Geometry Laser-Part II: Thermal Effects in a Finite Slab,Journal of Quantum Electronics, 1985, 21(20), 1195~1210
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