LD泵浦全固态瓦级473nm蓝光激光器
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摘要
LD泵浦的全固态激光器(Laser diode pumped solid-state laser或DPSSL)是激光技术领域的一个重要分支，与传统激光器相比在重量、体积、电—光转换效率、使用寿命和稳定性方面更具优越性。目前，LD泵浦全固态激光器已实现了连续、调Q脉冲和锁模脉冲等激光运转模式，广泛应用于材料加工、医疗、光学仪器和基础研究等领域。
目前，LD泵浦的小功率473nm全固态蓝光激光器已经基本成熟，但是在瓦级大功率方面发展还不成熟，尚需在理论和实验上进行更进一步的研究。为此，本文对蓝光大功率方面进行了深入研究，取得了一些有价值的结果，为LD泵浦全固态瓦级蓝光激光器的产业化奠定了坚实的基础，主要有以下几方面的工作：
1．从整体结构出发，分析了LD端面泵浦激光器模式匹配问题。
2．采用标准ABCD传输矩阵理论，对激光器腔模式进行了详细的分析，在充分考虑热效应的前提下，根据实际情况，合理设计出对热效应不敏感的三镜折叠腔，产生两个光腰，既满足了泵浦光能量的充分利用，也满足了缩小光腰提高倍频效率的要求。
3．从激光晶体的准三能级特性出发，充分考虑增益与损耗之间的矛盾，选择出最佳晶体长度；对三种倍频晶体进行了比较，选择出LBO作为主要倍频晶体；对膜系进行了必要的分析，在维持946nm谱线振荡的同时，充分考虑了其它激光谱线的抑制。
4．实验上采用对热效应不敏感的三镜折叠腔，LD泵浦Nd:YAG，Ⅰ类相位匹配LBO作为倍频晶体，获得了1.1瓦的连续473mn蓝光输出；采用腔内插入光阑的方法，有效克服了功率抖动，同时改善了光斑模式；实验中发现准三能级激光器存在两个空间模式匹配比例关系，并对这一现象给出了合理的解释。此外，对新型的倍频晶体BIBO也进行了一些初步的实验。
Laser Diode pumped solid-state laser(DPSSL) is an important branch in laser field. Continuous wave and pulse operation, Q-switching and mode-locking operation have been achieved for DPSSL which have a lot of uses in the field of medicine, process and so on.
Presently, the development of LD pumped, watt-level, solid-state blue laser is not mature, thus the theoretical and experimental research is necessary. Based on the present researches, some valuable results have been obtained.
1. Based on monolithic consideration, the problem of mode-matching was analyzed.
2. Introducing ABCD theory, the laser mode was analyzed; With thermal effect consideration, a short folded-cavity resonator which was not sensitive to thermal effect was designed. Thus, the requirements for efficient doubling frequency were satisfied.
3. The optimal length of crystal was achieved for the characteristics of quasi-three-level. Three types of crystal were compared, we select LBO as the main frequency doubler. Meanwhile, the other strong spectrum were restrained by suitable coating.
4. LD-pumped Nd:YAG, LBO (type-I critical phase matching) intracavity frequency doubled, blue laser at 473nm was obtained finally. Under the condition of 14W pump power, high power TEM00 mode blue laser at 473nm of 1.1W was obtained. By means of inserting diaphragm into cavity, the power fluctuation and beam mode were improved; In the experiments, the proportion of special mode matching in quasi-three-level laser was discovered, and the phenomenon were explained reasonedly. What's more, there were elementary experiments on BIBO, the new frequency doubler.
目前，LD泵浦的小功率473nm全固态蓝光激光器已经基本成熟，但是在瓦级大功率方面发展还不成熟，尚需在理论和实验上进行更进一步的研究。为此，本文对蓝光大功率方面进行了深入研究，取得了一些有价值的结果，为LD泵浦全固态瓦级蓝光激光器的产业化奠定了坚实的基础，主要有以下几方面的工作：
1．从整体结构出发，分析了LD端面泵浦激光器模式匹配问题。
2．采用标准ABCD传输矩阵理论，对激光器腔模式进行了详细的分析，在充分考虑热效应的前提下，根据实际情况，合理设计出对热效应不敏感的三镜折叠腔，产生两个光腰，既满足了泵浦光能量的充分利用，也满足了缩小光腰提高倍频效率的要求。
3．从激光晶体的准三能级特性出发，充分考虑增益与损耗之间的矛盾，选择出最佳晶体长度；对三种倍频晶体进行了比较，选择出LBO作为主要倍频晶体；对膜系进行了必要的分析，在维持946nm谱线振荡的同时，充分考虑了其它激光谱线的抑制。
4．实验上采用对热效应不敏感的三镜折叠腔，LD泵浦Nd:YAG，Ⅰ类相位匹配LBO作为倍频晶体，获得了1.1瓦的连续473mn蓝光输出；采用腔内插入光阑的方法，有效克服了功率抖动，同时改善了光斑模式；实验中发现准三能级激光器存在两个空间模式匹配比例关系，并对这一现象给出了合理的解释。此外，对新型的倍频晶体BIBO也进行了一些初步的实验。
Laser Diode pumped solid-state laser(DPSSL) is an important branch in laser field. Continuous wave and pulse operation, Q-switching and mode-locking operation have been achieved for DPSSL which have a lot of uses in the field of medicine, process and so on.
Presently, the development of LD pumped, watt-level, solid-state blue laser is not mature, thus the theoretical and experimental research is necessary. Based on the present researches, some valuable results have been obtained.
1. Based on monolithic consideration, the problem of mode-matching was analyzed.
2. Introducing ABCD theory, the laser mode was analyzed; With thermal effect consideration, a short folded-cavity resonator which was not sensitive to thermal effect was designed. Thus, the requirements for efficient doubling frequency were satisfied.
3. The optimal length of crystal was achieved for the characteristics of quasi-three-level. Three types of crystal were compared, we select LBO as the main frequency doubler. Meanwhile, the other strong spectrum were restrained by suitable coating.
4. LD-pumped Nd:YAG, LBO (type-I critical phase matching) intracavity frequency doubled, blue laser at 473nm was obtained finally. Under the condition of 14W pump power, high power TEM00 mode blue laser at 473nm of 1.1W was obtained. By means of inserting diaphragm into cavity, the power fluctuation and beam mode were improved; In the experiments, the proportion of special mode matching in quasi-three-level laser was discovered, and the phenomenon were explained reasonedly. What's more, there were elementary experiments on BIBO, the new frequency doubler.
引文
[1] 刘媛，方高瞻，马骁宇，肖建伟．大功率二极管泵浦固体激光器．激光与红外，2002，32(3)：139～142．
[2] R New man, et al. Excitation of the Nd~(3+) Fluorescence in Ca WO_4 by Recombination Radiation in Ga As. Journal of Applied Physics, 1963, 34(2):437.
[3] R J Keyes, et al. Injection Luminescent Pumping of CaF2U3+ with Ga As diode lasers. Applied Physics letters, 1964, 4(3):50～52.
[4] Monte Ross, et al. YAG Laser Operation by Semiconductor Laser Pumping. Proceedings of The IEEE, 1968, 56(2):196～197.
[5] Jack M.Gill. Lasers: A 40-Year Perspective. IEEE Journal on Selected Topics in Quantum Electronics, 2000, 6(6): 1111-1115
[6] D.Fluck, P.gunter. Efficient generation of CW blue light by sum-frequency mixing of laser diodes in KNbO_3. Optics Communications, 1997, 136:257-260
[7] D.Fluck, P.gunter. Second-harmonic generation by lens wave-griding in KNbO_3 crystals. Optics Communications, 1998, 147:305-308
[8] A.Ashkin, G.D.Boyd, J.M.Dziedzic. Resonant optical second harmonic generation and mixing. IEEE Journal of Quantum Electronics, 1966, 2(6): 109-124
[9] Xiao Guang Sun, John L. Carlsten. Low-noise blue light source with large frequency-scanning range from frequency doubling of a diode laser. J. Opt. Soc. Am. B, 2001, 18(3): 281285
[10] 檀慧明．全固态蓝光激光器的产品技术与市场应用．激光产品世界，2003，5(5)：13-20
[11] 郑权，王军营．LD泵浦473nm全固态蓝光激光器的研究进展．激光产品世界，2003，5(5)：28-33
[12] T.Y.Fan, R.L,Byer. Model and CW operation of a quasi-three-level 946nm Nd:YAG laser, IEEE Journal of Quantum Electronics, 1987, 23,605-612
[13] T.Y.Fan, R.L,Byer. Continuous-wave operation of a room-temperature, diode-laser-pumped, 946-nm Nd:YAG laser, Optics Letters, 1987, 12(10), 809-811
[14] W.P.Risk, W.Lenth. Room temperature, continuous-wave 946nm Nd:YAG laser pumped by laser diode arrays and intracavity frequency doubling to 473nm. Optics Letters, 1987,12(10),993-995
[15] W.P.Risk. Modeling of longitudinally pumped solid-state lasers exhibiting reabsorption losses. J.Opt.Xoc.Am.B, 1988, 5(7): 1412-1423
[16] P.Zzeller, P. Peuser. Efficient, multiwatt, continuous-wave laser operation on the transitions of Nd:YVO_4 and Nd:YAG. Optics Letters, 2000, 25(1): 34-36
[17] C.Czeranowsky, EHeumann, G.Huber. All-solid-state continuous-wave frequency-doubledNd:YAG-BiBO laser with 2.8-W output power at 473nm. Optics Letters, 2003, 28(6): 432-434
[18] 刘伟仁，钱龙生，檀慧明等．LD泵浦的946nm Nd：YAG激光器及腔内倍频473nm蓝光输出．激光杂志，2000，21(3)：12-13．
[19] 郑权，钱龙生．LD泵浦的高效率折叠腔YAG／LBO蓝光激光器．激光与红外，2001，31(3)：144-146
[20] 郑权，赵岭，邵永红．Cr：YAG被动调Q全固态473nm蓝光激光器．中国激光，2003，30(8)：673-676
[21] M.Pierrou and F.Laurell. Generation of 740mW of blue light by intracavity frequency doubling with a first-order quasi-phase-matched KTiOPO_4 crystal. Optics Letters, 1999;24(4):205～207
[22] C.Czeranowsky, M.Schmidt, E.Heumann, G.Huber, S.Kutovoi and Y.Zavartsev. Continuous wave diode pumped intracavity doubled Nd:GdVO_4 laser with 840mW output power at 456nm. Optics Communications, 2002; 20 (5) :361～365.
[23] 王军营，郑权．光纤耦合LDA泵浦，1.3W连续输出的473nm蓝光激光器．中国激光(已录用)
[24] 戴特立．半导体二极管泵浦固体激光器，四川大学出版社，1993
[25] 郑加安，赵圣之，晶体热效应对LD端面泵浦固体激光器优化设计的影响，光子学报，2001，30(6)：724～729
[26] 郑加安，赵圣之，LD端面泵浦Nd：YAG激光器热效应研究，光子学报，2000，29(12)：1121～1126
[27] Raymond J.Beach, CW Theory of quasi-three level end-pumped laser oscillators, Optic communication 1996, 385～393
[28] 周炳昆，激光原理，国防工业出版社2000，71～75
[29] Yung-Fu Chen, Diode-pumped Q-switched Nd:YVO_4 yellow laser with intracavity sum-frequency mixing[J], OPTICS LETTERS, 2002, 27(6):397-399
[30] 吕百达著．激光光学．四川大学出版社，第二版，1992：292～295
[31] 刘均海． 高功率端面抽运Nd：YVO_4 固体激光器模式匹配的研究．光学学报．2000，20(2)：186-189
[32] W．克希耐尔著，孙文等译．《固体激光工程》，科学出版社2002年，第一版：273
[33] New products.Laser Focus World, 2003, 39(6): 178
[34] 吕百达，固体激光工程，北京邮电大学出版社，2002，43～47
[35] 郑权，中国科学院长春光学精密机械与物理研究所博士学位论文．2002：
[36] W．克希耐尔 著，孙文，江泽文，程国祥 译．固体激光工程．第一版，科学出版社，2002：39-45
[37] Chun-Wei Wang, Passively Q-switched quasi-three-level laser and its intracavity frequency doubling[J]. APPLIED OPTICS, 2002,41 (6):1075-1081
[38] W．克希耐尔(著)，孙文(译)．固体激光工程[M]．科学出版社，2002：14～18
[39] TSO YEE FAN, Modeling and CW Operation of Quasi-Three-Level 946nm Nd:YAG Laser, IEEE JORNAL OF QUANTUM ELECTRONICS, 1987, 23(5):605～612
[40] 孟红祥，中国科学院长春光学精密机械与物理研究所博士学位论文．1998：
[41] 蓝信钜．激光技术[M]．第一版．北京：科学出版社，2001：219～236．
[42] Tim Kellner, Passive Q switching of a diode-pumped 946nm Nd:YAG laser with 1.6W average output power[J]. APPLOED OPTICS, 1998, 37(30):7076-7079
[43] Mssaki Tsunekane, Efficient 946nm laser opertion of a composite Nd:YAG rod with undoped ends[J]. APPLIED OPTICS, 1998,37(24):5713-5719
[44] P. Zeller, Efficient, multiwatt, continuous-wave laser operation on the 4F3/2-4I9/2 transitions of Nd:YVO4 and Nd:YAG[J]. OPTICS LETTERS, 2000,25(01):34-36
[45] 马红亮，张靖，王润林等．折叠腔内腔倍频激光器中基频与谐波相对相位对输出功率的影响．光子学报，2002，31(3)：321～323
[46] W．克希耐尔(著)，孙文(译)．固体激光工程[M]．科学出版社，2002：189～196
[47] 冯衍，LD抽运Nd：YVO4晶体中的上转换及其影响[J]。物理学报，2001，50(2)：335-340
[2] R New man, et al. Excitation of the Nd~(3+) Fluorescence in Ca WO_4 by Recombination Radiation in Ga As. Journal of Applied Physics, 1963, 34(2):437.
[3] R J Keyes, et al. Injection Luminescent Pumping of CaF2U3+ with Ga As diode lasers. Applied Physics letters, 1964, 4(3):50～52.
[4] Monte Ross, et al. YAG Laser Operation by Semiconductor Laser Pumping. Proceedings of The IEEE, 1968, 56(2):196～197.
[5] Jack M.Gill. Lasers: A 40-Year Perspective. IEEE Journal on Selected Topics in Quantum Electronics, 2000, 6(6): 1111-1115
[6] D.Fluck, P.gunter. Efficient generation of CW blue light by sum-frequency mixing of laser diodes in KNbO_3. Optics Communications, 1997, 136:257-260
[7] D.Fluck, P.gunter. Second-harmonic generation by lens wave-griding in KNbO_3 crystals. Optics Communications, 1998, 147:305-308
[8] A.Ashkin, G.D.Boyd, J.M.Dziedzic. Resonant optical second harmonic generation and mixing. IEEE Journal of Quantum Electronics, 1966, 2(6): 109-124
[9] Xiao Guang Sun, John L. Carlsten. Low-noise blue light source with large frequency-scanning range from frequency doubling of a diode laser. J. Opt. Soc. Am. B, 2001, 18(3): 281285
[10] 檀慧明．全固态蓝光激光器的产品技术与市场应用．激光产品世界，2003，5(5)：13-20
[11] 郑权，王军营．LD泵浦473nm全固态蓝光激光器的研究进展．激光产品世界，2003，5(5)：28-33
[12] T.Y.Fan, R.L,Byer. Model and CW operation of a quasi-three-level 946nm Nd:YAG laser, IEEE Journal of Quantum Electronics, 1987, 23,605-612
[13] T.Y.Fan, R.L,Byer. Continuous-wave operation of a room-temperature, diode-laser-pumped, 946-nm Nd:YAG laser, Optics Letters, 1987, 12(10), 809-811
[14] W.P.Risk, W.Lenth. Room temperature, continuous-wave 946nm Nd:YAG laser pumped by laser diode arrays and intracavity frequency doubling to 473nm. Optics Letters, 1987,12(10),993-995
[15] W.P.Risk. Modeling of longitudinally pumped solid-state lasers exhibiting reabsorption losses. J.Opt.Xoc.Am.B, 1988, 5(7): 1412-1423
[16] P.Zzeller, P. Peuser. Efficient, multiwatt, continuous-wave laser operation on the transitions of Nd:YVO_4 and Nd:YAG. Optics Letters, 2000, 25(1): 34-36
[17] C.Czeranowsky, EHeumann, G.Huber. All-solid-state continuous-wave frequency-doubledNd:YAG-BiBO laser with 2.8-W output power at 473nm. Optics Letters, 2003, 28(6): 432-434
[18] 刘伟仁，钱龙生，檀慧明等．LD泵浦的946nm Nd：YAG激光器及腔内倍频473nm蓝光输出．激光杂志，2000，21(3)：12-13．
[19] 郑权，钱龙生．LD泵浦的高效率折叠腔YAG／LBO蓝光激光器．激光与红外，2001，31(3)：144-146
[20] 郑权，赵岭，邵永红．Cr：YAG被动调Q全固态473nm蓝光激光器．中国激光，2003，30(8)：673-676
[21] M.Pierrou and F.Laurell. Generation of 740mW of blue light by intracavity frequency doubling with a first-order quasi-phase-matched KTiOPO_4 crystal. Optics Letters, 1999;24(4):205～207
[22] C.Czeranowsky, M.Schmidt, E.Heumann, G.Huber, S.Kutovoi and Y.Zavartsev. Continuous wave diode pumped intracavity doubled Nd:GdVO_4 laser with 840mW output power at 456nm. Optics Communications, 2002; 20 (5) :361～365.
[23] 王军营，郑权．光纤耦合LDA泵浦，1.3W连续输出的473nm蓝光激光器．中国激光(已录用)
[24] 戴特立．半导体二极管泵浦固体激光器，四川大学出版社，1993
[25] 郑加安，赵圣之，晶体热效应对LD端面泵浦固体激光器优化设计的影响，光子学报，2001，30(6)：724～729
[26] 郑加安，赵圣之，LD端面泵浦Nd：YAG激光器热效应研究，光子学报，2000，29(12)：1121～1126
[27] Raymond J.Beach, CW Theory of quasi-three level end-pumped laser oscillators, Optic communication 1996, 385～393
[28] 周炳昆，激光原理，国防工业出版社2000，71～75
[29] Yung-Fu Chen, Diode-pumped Q-switched Nd:YVO_4 yellow laser with intracavity sum-frequency mixing[J], OPTICS LETTERS, 2002, 27(6):397-399
[30] 吕百达著．激光光学．四川大学出版社，第二版，1992：292～295
[31] 刘均海． 高功率端面抽运Nd：YVO_4 固体激光器模式匹配的研究．光学学报．2000，20(2)：186-189
[32] W．克希耐尔著，孙文等译．《固体激光工程》，科学出版社2002年，第一版：273
[33] New products.Laser Focus World, 2003, 39(6): 178
[34] 吕百达，固体激光工程，北京邮电大学出版社，2002，43～47
[35] 郑权，中国科学院长春光学精密机械与物理研究所博士学位论文．2002：
[36] W．克希耐尔 著，孙文，江泽文，程国祥 译．固体激光工程．第一版，科学出版社，2002：39-45
[37] Chun-Wei Wang, Passively Q-switched quasi-three-level laser and its intracavity frequency doubling[J]. APPLIED OPTICS, 2002,41 (6):1075-1081
[38] W．克希耐尔(著)，孙文(译)．固体激光工程[M]．科学出版社，2002：14～18
[39] TSO YEE FAN, Modeling and CW Operation of Quasi-Three-Level 946nm Nd:YAG Laser, IEEE JORNAL OF QUANTUM ELECTRONICS, 1987, 23(5):605～612
[40] 孟红祥，中国科学院长春光学精密机械与物理研究所博士学位论文．1998：
[41] 蓝信钜．激光技术[M]．第一版．北京：科学出版社，2001：219～236．
[42] Tim Kellner, Passive Q switching of a diode-pumped 946nm Nd:YAG laser with 1.6W average output power[J]. APPLOED OPTICS, 1998, 37(30):7076-7079
[43] Mssaki Tsunekane, Efficient 946nm laser opertion of a composite Nd:YAG rod with undoped ends[J]. APPLIED OPTICS, 1998,37(24):5713-5719
[44] P. Zeller, Efficient, multiwatt, continuous-wave laser operation on the 4F3/2-4I9/2 transitions of Nd:YVO4 and Nd:YAG[J]. OPTICS LETTERS, 2000,25(01):34-36
[45] 马红亮，张靖，王润林等．折叠腔内腔倍频激光器中基频与谐波相对相位对输出功率的影响．光子学报，2002，31(3)：321～323
[46] W．克希耐尔(著)，孙文(译)．固体激光工程[M]．科学出版社，2002：189～196
[47] 冯衍，LD抽运Nd：YVO4晶体中的上转换及其影响[J]。物理学报，2001，50(2)：335-340