掺镱固体激光器辐射冷却原理与泵浦技术
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摘要
固体激光器辐射冷却原理是一个新概念,它的提出为降低增益介质中的热沉积量提供了一条新的技术途径。本文研究辐射冷却原理在固体激光器中的应用,通过反斯托克斯荧光的辐射冷却效应来减少掺镱激光介质在泵浦和受激辐射过程中所产生的热量,从而减小热效应对激光介质的不良影响。主要内容概括为:
1.综述了现有固体激光器的生热原理,以及反斯托克斯荧光冷却概念及其应用技术的发展历程。系统地叙述了辐射平衡激光器的基本理论,以及激光增益介质选取和工作波长优化的方法;
2.采用数值模拟方法,计算了辐射平衡条件下单程放大和振荡器掺镱介质(Yb: KGd(WO4)2)内光强的变化规律;
3.运用光线追迹的方法对二极管激光器(LD)侧面泵浦固体激光介质进行数值模拟,得到不同泵浦条件下Yb:KGW介质内泵浦光功率的分布。运用有限元分析软件ANSYS计算不同泵浦条件下介质内的温度分布,分析了影响介质内泵浦光功率分布及温度分布的因素。
本文的研究结果对设计辐射平衡激光器泵浦结构、解决传统固体激光器里的主要矛盾——提高激光输出功率与保持较好的光束质量——有一定的指导意义。
Optical refrigeration in solid-state lasers, as a new concept, can reduce the heat generated in laser medium in a different approach. Radiation balanced lasers (RBL) are analyzed through numerical simulation in this thesis. In RBL, the heat generation in the gain medium is compensated by optical refrigeration. The main work of the thesis is as follows:
1. Heat generation and thermal effects in solid-state lasers were summarized, along with the development of optical refrigeration which uses anti-Stokes fluorescence to realize cooling, and then the basic theories on RBL were represented. Yb:KGW was proposed as the candidate gain medium for RBL and wavelength condition must be satisfied in RBL;
2. The pump and laser intensity distributions are plotted in RBL of Yb:KGW under both the single-pass amplifier and resonator cavity conditions;
3. Side-pumped solid-state laser with low thermal loading was simulated numerically by ray-trace method, and the pump power distribution is calculated, under different conditions. Using the software ANSYS, we calculate the temperature distribution in medium. At last, the factors which affect the distribution of absorbed power and temperature are analyzed.
The conclusions of this paper have some instructional meanings to design the pump source in radiation-balanced lasers and settle the contradictory between increasing the output power and keeping beam quality.
1.综述了现有固体激光器的生热原理,以及反斯托克斯荧光冷却概念及其应用技术的发展历程。系统地叙述了辐射平衡激光器的基本理论,以及激光增益介质选取和工作波长优化的方法;
2.采用数值模拟方法,计算了辐射平衡条件下单程放大和振荡器掺镱介质(Yb: KGd(WO4)2)内光强的变化规律;
3.运用光线追迹的方法对二极管激光器(LD)侧面泵浦固体激光介质进行数值模拟,得到不同泵浦条件下Yb:KGW介质内泵浦光功率的分布。运用有限元分析软件ANSYS计算不同泵浦条件下介质内的温度分布,分析了影响介质内泵浦光功率分布及温度分布的因素。
本文的研究结果对设计辐射平衡激光器泵浦结构、解决传统固体激光器里的主要矛盾——提高激光输出功率与保持较好的光束质量——有一定的指导意义。
Optical refrigeration in solid-state lasers, as a new concept, can reduce the heat generated in laser medium in a different approach. Radiation balanced lasers (RBL) are analyzed through numerical simulation in this thesis. In RBL, the heat generation in the gain medium is compensated by optical refrigeration. The main work of the thesis is as follows:
1. Heat generation and thermal effects in solid-state lasers were summarized, along with the development of optical refrigeration which uses anti-Stokes fluorescence to realize cooling, and then the basic theories on RBL were represented. Yb:KGW was proposed as the candidate gain medium for RBL and wavelength condition must be satisfied in RBL;
2. The pump and laser intensity distributions are plotted in RBL of Yb:KGW under both the single-pass amplifier and resonator cavity conditions;
3. Side-pumped solid-state laser with low thermal loading was simulated numerically by ray-trace method, and the pump power distribution is calculated, under different conditions. Using the software ANSYS, we calculate the temperature distribution in medium. At last, the factors which affect the distribution of absorbed power and temperature are analyzed.
The conclusions of this paper have some instructional meanings to design the pump source in radiation-balanced lasers and settle the contradictory between increasing the output power and keeping beam quality.
引文
[1] W.克希耐尔著;孙文等译. 固体激光工程. 北京:科学出版社,2002.
[2]T.Y. Fan. Heat generation in Nd:YAG and Yb:YAG. IEEE J. Quantum Electron., 1993,29(6) :pp.1457-1459
[3] T. Kimura, K.Otsuka . Thermal effects of a continuously pumped Nd3+:YAG Laser. IEEE J. Quantum Electron., 1971,7(8):pp.403-407
[4] M. S. Mangir, D. A. Rockwell. Measurements of Heating and Energy Storage in Flashlamp-Pumped Nd:YAG and Nd-Doped Phosphate Laser Glasses. IEEE J. Quantum Electron., 1986, 22(4):pp.574-580
[5] D.C.Brown. heat, fluorescence ,and stimulated-emission power densities and fraction in Nd:YAG. IEEE J. Quantum Electron., 1998,34: pp.560-572
[6]杜少军,高能激光器及其发射系统的热变形研究,工学博士学位论文,2002
[7]J.Uppal, J.Monga, D.Bhawalkar. Study of Thermal Effects in Nd Doped Phosphate Glass Laser Rod. J.Quantum Electron, 1986,22(12):pp.2259～2265
[8]W.Koechner. Thermal Lensing in a Nd:YAG Laser Rod. Appl.Opl,1970,9:pp.2548～2553
[9]S.R.Bowman,Lasers without internal heat generation,IEEE J.Quantum Electronics,vol.35 (1999),pp.115-122.
[10]Sergey N.Andrianov and Vitaly V.Samartsev,Solid-state lasers with internal laser refrigeration effect,Proceedings of SPIE,vol.4605(2001),pp.208-113.
[11]N.Djeu and W.T.Whitney, Laser cooling by spontaneous anti-Stokes scattering,Phys.Rev. Lett.,vol.46(1981),pp.236-239.
[12]R.I.Epstein,M.I.Buchwald,B.C.Edward,T.R.Gosnell,and C.E.Mungan,Observation of laser -induced fluorescent cooling of a solid, Nature, vol.377(1995),pp.500-503.
[13]B.C.Edwards, J.E.Anderson, R.I.Epstein, G.L.Mills and A.J.Mord,Demonstration of a solid-state optical cooler: An approach to cryogenic refrigeration, Journ.of Appl.Phys,vol.86 (1999),pp.6489-6493.
[14]R.I.Epstein, J.J.Browm, B.C.Edwards, and A.Gibbs,Measurement of optical Refrigeration in ytterbium-doper crystals, Journ.of Appl.Phys,vol.90(2001),pp.4815-4819.
[15]Carl E.Mungan,Thermodynamics of radiation-balanced lasing, J.Opt.Soc.Am.B,vol.20,No.5 (2003),pp.1075-1082.
[16]S.R.Bowman, Shawn P.O’Connor, Subrat Biswal,Ytterbium Laser With Reduced Thermal Loading,IEEEJ. Quantum Electronics, vol.41(2005), pp. 1510-1517.
[17]汤珂,陈国邦,冯仰浦,激光制冷,低温与超导,2002,30(3):pp.5-11.
[18]秦伟平,反斯托克斯荧光制冷的研究进展与综述,物理学进展,2000,20(2):pp.93-167.
[19]张存泉,徐烈,反斯托克斯荧光制冷技术的研究,红外与激光工程,2002,3(2):pp.95-100.
[20]S.R.Bowman, C.E.Mungan, New materials for optical cooling, Appl.Phys.B71(2002),pp. 807-811.
[21]William F.Krupke, Ytterbium Solid-State Lasher—The First Decade, IEEE J.Quantum Electronics,vol.6(2000),pp.1287-1296.
[22]Laura D.DeLoach, Stephen A.Payne, L.L.Chase, Larry K.Smith, Wayne L.Kway, and Willian F.Krupke, Eavluation of absorption and emission properties of Yb3+ doped crystals for laser applications, IEEE J.Quantum Electronics,vol.29(1993),pp.1179-1191.
[23]S.R.Bowman, C.E.Mungan, Selecting materials for radiation balanced lasers, in Advanced Solid-State Lasers,Switzerland,2000.
[24]Material data sheets on Yb:KGW from EKSPLA Ltd.
[25]Chen Li,Qiang Liu,Mali Gong,Gang Chen, and Ping Yan, Modeling of radiation-balanced continuous-wave laser scillators, J.Opt.Soc.Am.B, vol.21 (2004), pp.539-542.
[26]S.R.Bowman, N.W.Jenkins, Shawn P.O’Connor, and Barry J.Feldman, Sensitivity and stability of a radiation-balanced laser system, IEEE J.Quantum Electronics,vol.38(2002),pp. 1339-1348.
[27]冷进勇,王晓峰等,辐射平衡激光器谐振腔模型计算,光学技术,vol.32 增刊 2006:pp.623-625.
[28]蔡志强,姚建铨等,LD 侧泵浦激光器抽运光和温度分布数值研究,光电子. 激光,2004,15(11):pp.1305-1310.
[29]Suganda Jutamulia, Guoguang Mu, Hongchen Zhai, Feijun Song, Use of laser diode in joint transform correlator, Optical Engineering,vol.43(2004),pp.1751-1758.
[30]赵存华,樊仲维等,一种 LD 侧面抽运固体激光棒光线追迹的数值模拟计算,激光技术,vol.29(2005):pp.404-406.
[31]宁继平,蔡志强等,LD 侧面抽运的 Nd:YAG 激光器抽运均匀性研究,中国激光,2004,31(4):pp.390-394.
[32]王建华,翟刚等,LD 直接侧面泵浦棒状介质的光场研究,激光技术,vol.28(2004):pp.36-38.41.
[33]梁铨廷,物理光学,杭州:浙江大学出版社,1997
[34]王建华,翟刚等,二极管阵列侧面泵浦固体激光介质的光场分布,红外与激光工程,2005,34(4):pp.421-426.458.
[35]崔兆云,曾晓东等,LD 光场柱透镜准直技术研究,激光杂志,2003,24(4):pp.14-15.
[36]刘媛媛,方高瞻等,侧面抽运 Nd:YAG 连续激光器,中国激光,2003,30(7):pp.577-580.
[37]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
[2]T.Y. Fan. Heat generation in Nd:YAG and Yb:YAG. IEEE J. Quantum Electron., 1993,29(6) :pp.1457-1459
[3] T. Kimura, K.Otsuka . Thermal effects of a continuously pumped Nd3+:YAG Laser. IEEE J. Quantum Electron., 1971,7(8):pp.403-407
[4] M. S. Mangir, D. A. Rockwell. Measurements of Heating and Energy Storage in Flashlamp-Pumped Nd:YAG and Nd-Doped Phosphate Laser Glasses. IEEE J. Quantum Electron., 1986, 22(4):pp.574-580
[5] D.C.Brown. heat, fluorescence ,and stimulated-emission power densities and fraction in Nd:YAG. IEEE J. Quantum Electron., 1998,34: pp.560-572
[6]杜少军,高能激光器及其发射系统的热变形研究,工学博士学位论文,2002
[7]J.Uppal, J.Monga, D.Bhawalkar. Study of Thermal Effects in Nd Doped Phosphate Glass Laser Rod. J.Quantum Electron, 1986,22(12):pp.2259～2265
[8]W.Koechner. Thermal Lensing in a Nd:YAG Laser Rod. Appl.Opl,1970,9:pp.2548～2553
[9]S.R.Bowman,Lasers without internal heat generation,IEEE J.Quantum Electronics,vol.35 (1999),pp.115-122.
[10]Sergey N.Andrianov and Vitaly V.Samartsev,Solid-state lasers with internal laser refrigeration effect,Proceedings of SPIE,vol.4605(2001),pp.208-113.
[11]N.Djeu and W.T.Whitney, Laser cooling by spontaneous anti-Stokes scattering,Phys.Rev. Lett.,vol.46(1981),pp.236-239.
[12]R.I.Epstein,M.I.Buchwald,B.C.Edward,T.R.Gosnell,and C.E.Mungan,Observation of laser -induced fluorescent cooling of a solid, Nature, vol.377(1995),pp.500-503.
[13]B.C.Edwards, J.E.Anderson, R.I.Epstein, G.L.Mills and A.J.Mord,Demonstration of a solid-state optical cooler: An approach to cryogenic refrigeration, Journ.of Appl.Phys,vol.86 (1999),pp.6489-6493.
[14]R.I.Epstein, J.J.Browm, B.C.Edwards, and A.Gibbs,Measurement of optical Refrigeration in ytterbium-doper crystals, Journ.of Appl.Phys,vol.90(2001),pp.4815-4819.
[15]Carl E.Mungan,Thermodynamics of radiation-balanced lasing, J.Opt.Soc.Am.B,vol.20,No.5 (2003),pp.1075-1082.
[16]S.R.Bowman, Shawn P.O’Connor, Subrat Biswal,Ytterbium Laser With Reduced Thermal Loading,IEEEJ. Quantum Electronics, vol.41(2005), pp. 1510-1517.
[17]汤珂,陈国邦,冯仰浦,激光制冷,低温与超导,2002,30(3):pp.5-11.
[18]秦伟平,反斯托克斯荧光制冷的研究进展与综述,物理学进展,2000,20(2):pp.93-167.
[19]张存泉,徐烈,反斯托克斯荧光制冷技术的研究,红外与激光工程,2002,3(2):pp.95-100.
[20]S.R.Bowman, C.E.Mungan, New materials for optical cooling, Appl.Phys.B71(2002),pp. 807-811.
[21]William F.Krupke, Ytterbium Solid-State Lasher—The First Decade, IEEE J.Quantum Electronics,vol.6(2000),pp.1287-1296.
[22]Laura D.DeLoach, Stephen A.Payne, L.L.Chase, Larry K.Smith, Wayne L.Kway, and Willian F.Krupke, Eavluation of absorption and emission properties of Yb3+ doped crystals for laser applications, IEEE J.Quantum Electronics,vol.29(1993),pp.1179-1191.
[23]S.R.Bowman, C.E.Mungan, Selecting materials for radiation balanced lasers, in Advanced Solid-State Lasers,Switzerland,2000.
[24]Material data sheets on Yb:KGW from EKSPLA Ltd.
[25]Chen Li,Qiang Liu,Mali Gong,Gang Chen, and Ping Yan, Modeling of radiation-balanced continuous-wave laser scillators, J.Opt.Soc.Am.B, vol.21 (2004), pp.539-542.
[26]S.R.Bowman, N.W.Jenkins, Shawn P.O’Connor, and Barry J.Feldman, Sensitivity and stability of a radiation-balanced laser system, IEEE J.Quantum Electronics,vol.38(2002),pp. 1339-1348.
[27]冷进勇,王晓峰等,辐射平衡激光器谐振腔模型计算,光学技术,vol.32 增刊 2006:pp.623-625.
[28]蔡志强,姚建铨等,LD 侧泵浦激光器抽运光和温度分布数值研究,光电子. 激光,2004,15(11):pp.1305-1310.
[29]Suganda Jutamulia, Guoguang Mu, Hongchen Zhai, Feijun Song, Use of laser diode in joint transform correlator, Optical Engineering,vol.43(2004),pp.1751-1758.
[30]赵存华,樊仲维等,一种 LD 侧面抽运固体激光棒光线追迹的数值模拟计算,激光技术,vol.29(2005):pp.404-406.
[31]宁继平,蔡志强等,LD 侧面抽运的 Nd:YAG 激光器抽运均匀性研究,中国激光,2004,31(4):pp.390-394.
[32]王建华,翟刚等,LD 直接侧面泵浦棒状介质的光场研究,激光技术,vol.28(2004):pp.36-38.41.
[33]梁铨廷,物理光学,杭州:浙江大学出版社,1997
[34]王建华,翟刚等,二极管阵列侧面泵浦固体激光介质的光场分布,红外与激光工程,2005,34(4):pp.421-426.458.
[35]崔兆云,曾晓东等,LD 光场柱透镜准直技术研究,激光杂志,2003,24(4):pp.14-15.
[36]刘媛媛,方高瞻等,侧面抽运 Nd:YAG 连续激光器,中国激光,2003,30(7):pp.577-580.
[37]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