端面抽运Tm，Ho：YLF连续激光器参数优化及热效应研究
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摘要
LD抽运的Tm，Ho：YLF固体激光器除具有一般LD抽运固体激光器的高功率、紧凑、稳定、长寿命和全固态等优点外，它的输出波长处于人眼安全波段，更适合在人群密集的地方应用。这种激光器的热效应相对较弱，储存能量能力强，是获得3-5μm波段光学参量振荡激光输出必要的泵浦源，在军事激光系统，大气遥感和医学应用领域显示出了越来越光明的应用前景。本论文围绕LD端面抽运Tm，Ho：YLF连续固体激光器在理论与实验两方面开展研究工作。
理论上，在分析了Tm，Ho系统的能级结构，运行机制，相关参数的基础上，给出了与空间相关的准三能级速率方程理论模型。基于此速率方程理论模型，利用matlab软件对激光器的输出与输入关系进行了相应的数值模拟，对激光晶体的粒子掺杂浓度、晶体长度、输出镜透过率等参数进行了优化。根据端面抽运侧向导热的理论模型，在热传导方程的基础上，我们分析了Tm，Ho：YLF固体激光系统的热功率损耗、热形变、热透镜焦距、热脆裂等效应，并进行了数值模拟。
实验上，在近室温下进行了激光二极管端面抽运平凹腔Tm，Ho：YLF固体激光器的实验研究。给出了Tm，Ho：YLF固体激光器输出功率随抽运功率的变化关系，并利用小孔扫描法测出了热透镜焦距随抽运功率的变化规律。利用光纤耦合输出激光二极管抽运Tm，Ho：YLF激光晶体，测出了Tm，Ho：YLF激光晶体的热脆裂阈值。
Besides characteristics of ordinary LD-pumped solid-state laser, LD-pumped Tm,Ho:YLF laser has high power output, compact structure, stable performance, long lifetime and all-solid-state. It's eye-safe and fit to crowd places. This kind of laser has relatively weak thermal effects and high energy storage, and it is an ideal pump source of 3～5μm optical parametric oscillator (OPO). In the system of military laser, atmosphere sensing and application of medicine, this kind of laser indicates promising foreground. This paper investigates and explores both theoretically and experimentally in the field of the diode-end-pumped continuous wave Tm,Ho:YLF laser.
Theoretically, we have analyzed the level structure, mechanism, relative parameters of Tm,Ho:YLF, and the rate equations are given. In order to optimize the parameters, the laser threshold and the characteristics of the laser output are analyzed and simulated in mat-lab language based on the model of rate equations. On the basis of the heat conduction equation, we analyzed some heat-induced effects of the Tm,Ho:YLF solid-state laser, such as thermal power losses, thermal deformation, thermal focal length, thermal fracture to get a comprehensive understanding of the system.
Experimentally, the diode-end-pumped plane-concave cavity Tm,Ho:YLF laser is studied at room temperature. The output powers as a function of incident pump power are given. Furthermore, the thermal focal lengths as a function of pump power are obtained by the method of small-hole scanning. At the same time, the thermal fracture threshold is measured by using the fiber-coupled laser diode to pump the Tm,Ho:YLF laser crystal.
理论上，在分析了Tm，Ho系统的能级结构，运行机制，相关参数的基础上，给出了与空间相关的准三能级速率方程理论模型。基于此速率方程理论模型，利用matlab软件对激光器的输出与输入关系进行了相应的数值模拟，对激光晶体的粒子掺杂浓度、晶体长度、输出镜透过率等参数进行了优化。根据端面抽运侧向导热的理论模型，在热传导方程的基础上，我们分析了Tm，Ho：YLF固体激光系统的热功率损耗、热形变、热透镜焦距、热脆裂等效应，并进行了数值模拟。
实验上，在近室温下进行了激光二极管端面抽运平凹腔Tm，Ho：YLF固体激光器的实验研究。给出了Tm，Ho：YLF固体激光器输出功率随抽运功率的变化关系，并利用小孔扫描法测出了热透镜焦距随抽运功率的变化规律。利用光纤耦合输出激光二极管抽运Tm，Ho：YLF激光晶体，测出了Tm，Ho：YLF激光晶体的热脆裂阈值。
Besides characteristics of ordinary LD-pumped solid-state laser, LD-pumped Tm,Ho:YLF laser has high power output, compact structure, stable performance, long lifetime and all-solid-state. It's eye-safe and fit to crowd places. This kind of laser has relatively weak thermal effects and high energy storage, and it is an ideal pump source of 3～5μm optical parametric oscillator (OPO). In the system of military laser, atmosphere sensing and application of medicine, this kind of laser indicates promising foreground. This paper investigates and explores both theoretically and experimentally in the field of the diode-end-pumped continuous wave Tm,Ho:YLF laser.
Theoretically, we have analyzed the level structure, mechanism, relative parameters of Tm,Ho:YLF, and the rate equations are given. In order to optimize the parameters, the laser threshold and the characteristics of the laser output are analyzed and simulated in mat-lab language based on the model of rate equations. On the basis of the heat conduction equation, we analyzed some heat-induced effects of the Tm,Ho:YLF solid-state laser, such as thermal power losses, thermal deformation, thermal focal length, thermal fracture to get a comprehensive understanding of the system.
Experimentally, the diode-end-pumped plane-concave cavity Tm,Ho:YLF laser is studied at room temperature. The output powers as a function of incident pump power are given. Furthermore, the thermal focal lengths as a function of pump power are obtained by the method of small-hole scanning. At the same time, the thermal fracture threshold is measured by using the fiber-coupled laser diode to pump the Tm,Ho:YLF laser crystal.
引文
[1] 胡世高．固体激光器的军事应用．红外与激光技术．1991：38-48
[2] T.Y.Fan, R.L.Byer. Diode laser pumped solid-state lasers. IEEE JQE. 1988, 24: 895-912
[3] G.L.Bourdet, R.A.Muller. Tm, Ho: YLF microchip laser under Ti: sapphire and diode pumping. Appl.. Phs. 2000, 70: 345-350
[4] H.R.Lee, J.Yu, N.P.Barnes, Y.Bai. High Pulse Energy ZnGeP_2 Singly Resonant OPO.OSA Trends in Optics and Photonics Series. 2004, 94: 390-398
[5] P.A.Nudni, A.Pomeranz, M.L.Lemous, P.G.Schunemann, T.M.Pollak, E.P. Chicklis. 10W Mid-IR Holmium Pumped ZnGeP_2 OPO.OSA TOPS Advanced Solid-State Lasers. 1998, 19: 225-229
[6] P.A.Budni, L.A. Pomeranz, M.L.Lemous, C.A.Miller, J.R.Mosto, E.P.Chicklis. Efficient mid-infrared laser using 1.9-μm-pumped Ho:YAG and ZnGeP_2 optical parametric oscillators. J. Opt. Soc. Am. B. 2000, 17: 723-729
[7] S.W.Henderson, P.J.M.Suni, C.P.Hale, S.M.Hannon, J.R.Magee, D.L.Bruns, E.H.Yuen. Coherent Laser Radar at 2μm Using Solid-State Lasers. IEEE J.Quantum Electron. 1993, 31: 4-10
[8] G.J.Koch, R.E.Davis, A.N.Dharamsi, M.Petros, J.C.McCarthy. Differential Absorption Measurements of Atmospheric Water Vapor with A Coherent Lidar at 2050.532nm. Proceedings of Tenth Biennial Coherent Laser Radar Technology and Applications Conference. 1999: 69-72
[9] G.J.Koch, A.N.Dharamsi, C.M.Fitzgerald, J.C.McCarthy. Frequency Stabilization of A Ho,Tm: YLF Laser to Absorption Lines of Carbon Dioxide. Appl Opt. 2000, 39: 3664-3670
[10] G.J.Koch, M.Petros, J.Yu, U.N.Singh. Precise Wavelength Control of a Single -frequency Pulsed Ho,Tm:YLF Laser. APP. Opt. 2002, 41: 1715-1720
[11] S.W.Henderson, C.P.Hale, H.R.Magee, M.J.Kavaya, A.V.Huffaker. Eyesafe Coherent Laser Radar.Opt.Lett. 1991, 16: 773-776
[12] 刘福云，曹余惠．固体相干激光雷达系统的发展．光电子技术与信息．1996，9：6-12
[13] 刘福云，曹余惠．Tm：YAG激光器及其应用前景．激光与红外．1997，27：70-74
[14] 杨羊．LDA侧面抽运Nd：YVO4激光器设计．南京理工大学硕士学位论文集．2005：2-5
[15] B.T.McGuckin, R.T.Menzies, H.Hemmati. Efficient Energy Extraction from A Diode-Pumped Q-switched Tm,Ho:YLF Laser. Appl. Phys. Lett. 1991, 59: 2926-2929
[16] B.T.McGuckin, R.T.Menzies. Efficient CW Diode-Pumped Tm,Ho:YLF Laser with Tunability Near 2.067μm. IEEE J.Quantum Electronics. 1992, 28: 1025-1030
[17] C.J.Lee, G.Han, N.P.Barnes. Ho,Tm Lasers: Experiments. IEEE J.Quantum Electronics. 1996, 32: 104-108
[18] G.Ruatad, K.Stenersen. Modeling of Laser-Pumped Tm and Ho Laser Accounting for Upconversion and Ground-State Depletion. IEEE J. Quantum Electronics. 1996, 32: 1645-1648
[19] I.F.Elder, M.J.Payne. Single frequency diode-pumped Tm,Ho:YLF laser. IEEE J.Quantum Electronics. 1998, 34: 284-285
[20] A.Y.sunckane, N.T.aguchj, H.Inaba. Improvement of thermal effects in a diode-end-pumped, composite Tm:YAG rod with undoped ends. Appl. Opt. 1999, 38: 1788-1789
[21] Jun Izawa, Hayato Nakajima, Hiroshi Hara, Yoshinori Arimoto. A tunable and longitudinal node oscillation of a Tm,Ho:YLF microchip laser using an external etalon, Opt. Commun. 2000, 180: 137-140
[22] F.Cornacchia, E.Sani, A.Toncelli, M.Tonelli. Comparative Analysis of Diode Pumped cw Tm,Ho:YLF and Tm,Ho:BaYF lasers at 2μm. CLEO. 2002: 122
[23] M.Higuchi, C.Kodaira. Diode-Pumped continuous wave Tm,Ho: GdVO_4laser in room temperature. CLEO. 2005: 57
[24] 高恒．LD侧面抽运全固态大功率绿光及紫外光激光器研究．西北大学硕士学位论文集．2006：11
[25] G.Rustad, K.Stenersen. Low Threshold Laser-Diode Side-Pumped Tm:YAG and Tm,Ho:YAG Lasers. IEEE J.Quantum Electron. 1997, 3: 82-88
[26] J.P.Foing, E.Scheer. Diode pumped emission of Tm~(3+) doped Ca_2Al_2SiO_7 crystals. Appl Opt. 1995, 34: 4310-4315
[27] C.P.Wyss, W.Luthy, H.P.Weber, V.E.Vlasov, Yu.D.Zavartsev. Performanc of a Tm~(3+):GdVO_4 microchip laser at 1.9um.Opt. Commun. 1998, 153: 63-67
[28] M.A.Noginov, H.J.Caulfield, P.Venkateswariu, M.Mahadi, L.T.Sorokina. Light-induced grating study of excitation migration in Er,Tm and Ho-doped YSGG laser crystals. CLEO. 1996: 282-283
[29] B.M.Walsh. Spectroscopy and Excitation Dynamics of the Trivalent Lanthanides Tm~(3+) and Ho~(3+) in LiYF_4. Appl. Phys. 2004: 11916-11917
[30] M.E.Storm. Holmium YLF Amplifier Performance and the Prospects for Multi-Joule Energies Using Dilde-Laser Pumping. IEEE J.Quantum Electronics. 1993, 29: 440-451
[31] Y.Y.Fan, G.Huber, R.L.Byer. Spectroscopy and Diode Laser-Pumped Operation of Tm,Ho:YAG. IEEE J. Quantum. 1988, 24: 924-933
[32] C.Nagasawa, T.Suzuki, H.Nakajima, H.Hara, K.Mizutani. Characteristics of single longitudinal mode oscillation of the 2um Tm,Ho:YLF microchip laser. Optical Communications. 2001: 315-319
[33] M.Doshida, K.Teraguchi, M.Abara. Gain Measurement and upconversion analysis in Tm~(3+),Ho~(3+)co-doped alumino-zirco-fluoride glass. IEEE J.Quant um. 1995, 31: 910-915
[34] S.Taccheo, G.Galzerano, C.Svelto, P.Laporta. Suppression of Intensity Noise in A Diode-pumped Tm-Ho:YAG Laser. Opt. Lett. 2000, 25: 1642-1645
[35] M.Schellhorn, A.Hirth. Modeling of Intracavity-Pumped Quasi-three-Level Lasers. IEEE J. Quantum. 2002, 38: 1455-1464
[36] S.Atsushi, A.Kazuhiro, I.Toshikazu. Double-pass-pumped Tm:YAG laser with a simple cavity configuration. Optical Society of America. 1998, 37: 6395-6400
[37] 史彭，李隆，甘安生，凌亚文，刘小芳，白晋涛．端面抽运矩形截面Nd：GdVO4晶体热效应研究．中国激光．2005，32：923-928
[38] C.Pfistner, P.Albers, H.P.Weber, S.Merazzi, R.Gribe. Thermal Beam Distortions in end-pumped Nd:YAG, Nd:GsGG, and Nd:YLF Rods. IEEE J. Quantum Electronics. 1994, 30: 1605-1612
[39] Y.F.Chen, T.M.Huang, C.F.Kao, C.L.Wang, S.C.Wang. Optimization in Scaling Fiber-coupled Laser-diode End-pumped Lasers to Higher Power: Influence of Thermal Effect. IEEE J.Quantum Electronics. 1997, 33: 1424-1428
[40] Y.F.Chen. Pump-to-mode Size Ratio Dependence of Thermal Loading in Diode-end-pump Solid-state Lasers. J. Opt. Soc. Am. B. 2000, 17: 1835-1840
[2] T.Y.Fan, R.L.Byer. Diode laser pumped solid-state lasers. IEEE JQE. 1988, 24: 895-912
[3] G.L.Bourdet, R.A.Muller. Tm, Ho: YLF microchip laser under Ti: sapphire and diode pumping. Appl.. Phs. 2000, 70: 345-350
[4] H.R.Lee, J.Yu, N.P.Barnes, Y.Bai. High Pulse Energy ZnGeP_2 Singly Resonant OPO.OSA Trends in Optics and Photonics Series. 2004, 94: 390-398
[5] P.A.Nudni, A.Pomeranz, M.L.Lemous, P.G.Schunemann, T.M.Pollak, E.P. Chicklis. 10W Mid-IR Holmium Pumped ZnGeP_2 OPO.OSA TOPS Advanced Solid-State Lasers. 1998, 19: 225-229
[6] P.A.Budni, L.A. Pomeranz, M.L.Lemous, C.A.Miller, J.R.Mosto, E.P.Chicklis. Efficient mid-infrared laser using 1.9-μm-pumped Ho:YAG and ZnGeP_2 optical parametric oscillators. J. Opt. Soc. Am. B. 2000, 17: 723-729
[7] S.W.Henderson, P.J.M.Suni, C.P.Hale, S.M.Hannon, J.R.Magee, D.L.Bruns, E.H.Yuen. Coherent Laser Radar at 2μm Using Solid-State Lasers. IEEE J.Quantum Electron. 1993, 31: 4-10
[8] G.J.Koch, R.E.Davis, A.N.Dharamsi, M.Petros, J.C.McCarthy. Differential Absorption Measurements of Atmospheric Water Vapor with A Coherent Lidar at 2050.532nm. Proceedings of Tenth Biennial Coherent Laser Radar Technology and Applications Conference. 1999: 69-72
[9] G.J.Koch, A.N.Dharamsi, C.M.Fitzgerald, J.C.McCarthy. Frequency Stabilization of A Ho,Tm: YLF Laser to Absorption Lines of Carbon Dioxide. Appl Opt. 2000, 39: 3664-3670
[10] G.J.Koch, M.Petros, J.Yu, U.N.Singh. Precise Wavelength Control of a Single -frequency Pulsed Ho,Tm:YLF Laser. APP. Opt. 2002, 41: 1715-1720
[11] S.W.Henderson, C.P.Hale, H.R.Magee, M.J.Kavaya, A.V.Huffaker. Eyesafe Coherent Laser Radar.Opt.Lett. 1991, 16: 773-776
[12] 刘福云，曹余惠．固体相干激光雷达系统的发展．光电子技术与信息．1996，9：6-12
[13] 刘福云，曹余惠．Tm：YAG激光器及其应用前景．激光与红外．1997，27：70-74
[14] 杨羊．LDA侧面抽运Nd：YVO4激光器设计．南京理工大学硕士学位论文集．2005：2-5
[15] B.T.McGuckin, R.T.Menzies, H.Hemmati. Efficient Energy Extraction from A Diode-Pumped Q-switched Tm,Ho:YLF Laser. Appl. Phys. Lett. 1991, 59: 2926-2929
[16] B.T.McGuckin, R.T.Menzies. Efficient CW Diode-Pumped Tm,Ho:YLF Laser with Tunability Near 2.067μm. IEEE J.Quantum Electronics. 1992, 28: 1025-1030
[17] C.J.Lee, G.Han, N.P.Barnes. Ho,Tm Lasers: Experiments. IEEE J.Quantum Electronics. 1996, 32: 104-108
[18] G.Ruatad, K.Stenersen. Modeling of Laser-Pumped Tm and Ho Laser Accounting for Upconversion and Ground-State Depletion. IEEE J. Quantum Electronics. 1996, 32: 1645-1648
[19] I.F.Elder, M.J.Payne. Single frequency diode-pumped Tm,Ho:YLF laser. IEEE J.Quantum Electronics. 1998, 34: 284-285
[20] A.Y.sunckane, N.T.aguchj, H.Inaba. Improvement of thermal effects in a diode-end-pumped, composite Tm:YAG rod with undoped ends. Appl. Opt. 1999, 38: 1788-1789
[21] Jun Izawa, Hayato Nakajima, Hiroshi Hara, Yoshinori Arimoto. A tunable and longitudinal node oscillation of a Tm,Ho:YLF microchip laser using an external etalon, Opt. Commun. 2000, 180: 137-140
[22] F.Cornacchia, E.Sani, A.Toncelli, M.Tonelli. Comparative Analysis of Diode Pumped cw Tm,Ho:YLF and Tm,Ho:BaYF lasers at 2μm. CLEO. 2002: 122
[23] M.Higuchi, C.Kodaira. Diode-Pumped continuous wave Tm,Ho: GdVO_4laser in room temperature. CLEO. 2005: 57
[24] 高恒．LD侧面抽运全固态大功率绿光及紫外光激光器研究．西北大学硕士学位论文集．2006：11
[25] G.Rustad, K.Stenersen. Low Threshold Laser-Diode Side-Pumped Tm:YAG and Tm,Ho:YAG Lasers. IEEE J.Quantum Electron. 1997, 3: 82-88
[26] J.P.Foing, E.Scheer. Diode pumped emission of Tm~(3+) doped Ca_2Al_2SiO_7 crystals. Appl Opt. 1995, 34: 4310-4315
[27] C.P.Wyss, W.Luthy, H.P.Weber, V.E.Vlasov, Yu.D.Zavartsev. Performanc of a Tm~(3+):GdVO_4 microchip laser at 1.9um.Opt. Commun. 1998, 153: 63-67
[28] M.A.Noginov, H.J.Caulfield, P.Venkateswariu, M.Mahadi, L.T.Sorokina. Light-induced grating study of excitation migration in Er,Tm and Ho-doped YSGG laser crystals. CLEO. 1996: 282-283
[29] B.M.Walsh. Spectroscopy and Excitation Dynamics of the Trivalent Lanthanides Tm~(3+) and Ho~(3+) in LiYF_4. Appl. Phys. 2004: 11916-11917
[30] M.E.Storm. Holmium YLF Amplifier Performance and the Prospects for Multi-Joule Energies Using Dilde-Laser Pumping. IEEE J.Quantum Electronics. 1993, 29: 440-451
[31] Y.Y.Fan, G.Huber, R.L.Byer. Spectroscopy and Diode Laser-Pumped Operation of Tm,Ho:YAG. IEEE J. Quantum. 1988, 24: 924-933
[32] C.Nagasawa, T.Suzuki, H.Nakajima, H.Hara, K.Mizutani. Characteristics of single longitudinal mode oscillation of the 2um Tm,Ho:YLF microchip laser. Optical Communications. 2001: 315-319
[33] M.Doshida, K.Teraguchi, M.Abara. Gain Measurement and upconversion analysis in Tm~(3+),Ho~(3+)co-doped alumino-zirco-fluoride glass. IEEE J.Quant um. 1995, 31: 910-915
[34] S.Taccheo, G.Galzerano, C.Svelto, P.Laporta. Suppression of Intensity Noise in A Diode-pumped Tm-Ho:YAG Laser. Opt. Lett. 2000, 25: 1642-1645
[35] M.Schellhorn, A.Hirth. Modeling of Intracavity-Pumped Quasi-three-Level Lasers. IEEE J. Quantum. 2002, 38: 1455-1464
[36] S.Atsushi, A.Kazuhiro, I.Toshikazu. Double-pass-pumped Tm:YAG laser with a simple cavity configuration. Optical Society of America. 1998, 37: 6395-6400
[37] 史彭，李隆，甘安生，凌亚文，刘小芳，白晋涛．端面抽运矩形截面Nd：GdVO4晶体热效应研究．中国激光．2005，32：923-928
[38] C.Pfistner, P.Albers, H.P.Weber, S.Merazzi, R.Gribe. Thermal Beam Distortions in end-pumped Nd:YAG, Nd:GsGG, and Nd:YLF Rods. IEEE J. Quantum Electronics. 1994, 30: 1605-1612
[39] Y.F.Chen, T.M.Huang, C.F.Kao, C.L.Wang, S.C.Wang. Optimization in Scaling Fiber-coupled Laser-diode End-pumped Lasers to Higher Power: Influence of Thermal Effect. IEEE J.Quantum Electronics. 1997, 33: 1424-1428
[40] Y.F.Chen. Pump-to-mode Size Ratio Dependence of Thermal Loading in Diode-end-pump Solid-state Lasers. J. Opt. Soc. Am. B. 2000, 17: 1835-1840