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1972年1月15日,贝尔实验室的R. H. Stolen等在Applied Physics Letters上发表题为“玻璃光波导中的拉曼振荡(Raman Oscillation in Glass Optical Waveguide)”一文[6],首次报道了利用光纤中SRS效应实现激光输出。实验系统示意图如图1所示,图中的光纤是康宁公司生产的单模全固态光纤,纤芯直径为4 μm,泵浦源是波长为532 nm的脉冲激光,对应的一阶Stokes光波长为545 nm。相比于液体和晶体,玻璃的拉曼增益要低约2个数量级,但得益于光纤中的功率密度高、作用距离长等特点,低损耗光纤的拉曼效应产生阈值同样可能比较低。实验中,分别在单程传输和谐振腔中实现了拉曼信号光输出。
同年11月,贝尔实验室的R. G. Smith在Applied Optics上发表与RFLs相关的理论文章[27]。文章通过一系列简化和近似,从功率偏微分方程分别推导出稳态或连续单频泵浦光经光纤单程传输后产生前向SRS、后向SRS和受激布里渊散射(Stimulated Brillouin Scattering, SBS)效应的阈值近似公式,分别为:
$$ P^{forward}_{SRS}=16(A\alpha _{p}/\gamma _{0}) $$ (1) $$ \begin{split} \\ P^{backward}_{SRS}=20(A\alpha _{p}/\gamma _{0}) \end{split} $$ (2) $$ P_{SBS}=21(A\alpha _{p}/\gamma _{0}) $$ (3) 上述三个公式形式相同。A为纤芯面积,αp为泵浦光纤损耗,γ0为增益常数。对于纤芯面积为10−7 cm2、光纤损耗为20 dB/km的光纤,估算的前向SRS阈值和后向SBS阈值分别为1 W和35 mW。文章讨论了限制单频泵浦光纤激光功率的主要因素(SBS);对于宽带泵浦(纵模较多,线宽较宽),SBS的增益系数下降,此时SRS将成为限制功率的主要因素。
1972年发表的两篇文章分别奠定了拉曼光纤激光技术的实验与理论基础,揭示了SRS效应既能成为激光产生与放大的新途径,也会成为光纤激光功率的限制因素。在Web of Science数据库中检索,迄今为止,上述两篇论文的引用次数分别超过600次和800次,已经成为光纤激光甚至是整个激光技术领域的代表性经典文献。
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由泵浦光纤激光器、高反射率FBG、拉曼增益光纤和输出耦合FBG组成的振荡器结构是RFL最为经典的结构。表1和图5分别展示了近年来高亮度激光输出的拉曼振荡器的功率发展趋势。目前,基于振荡器结构输出的RFLs最高功率是以色列索克雷核研究所的Glick等于2018年报道的1.2 kW级RFLs,所用拉曼光纤为特殊设计的三包层光纤(纤芯、内包层、外包层直径分别为25 μm、45 μm与250 μm)[85],1 kW输出功率下光束质量M2因子为2.75,亮度提升倍数约为7。2017年,俄罗斯科学院Babin等通过在纤芯为62.5 μm的多模GRIN光纤中刻写光栅,将GRIN光纤光束净化效果与光栅选模特性相结合,报道了首个基于GRIN光纤的全光纤化RFLs,实现了50 W的拉曼激光输出,光束质量M2因子由泵浦光的26提升至信号光的2.6,对应的激光亮度提升了25倍2.6,对应的激光亮度提升了25倍[94];次年,该课题组将GRIN光纤纤芯增加至100 μm,从而进一步提高注入泵浦功率,实现了62 W拉曼激光输出,光束质量M2因子由泵浦光的30提升至信号光的3,亮度提升了30倍[97]。2021年,该课题组通过优化实验结构进一步提升了激光器输出光束质量,最高输出功率为52 W时,光束质量M2因子由泵浦光的34提升至信号光的2,对应的亮度增强因子为73,为目前公开报道的GRIN光纤激光器中的最高亮度增强因子[99];同年,该课题组通过在相似的结构中采用级联泵浦的方式获得了最高输出功率为12 W的近衍射极限的拉曼激光输出,最高功率下的光束质量M2因子为1.3[100]。国防科技大学课题组的Chenchen Fan等基于GRIN光纤搭建了全光纤结构的RFLs,实现了443 W的激光输出,对应光束质量M2为3.5,亮度提升倍数为4.2[101],为目前同类型激光器的最高输出功率值。
表 1 近年来拉曼光纤振荡器的研究进展
Table 1. Research progress of Raman fiber oscillator in recent years
Years Research institute Power
/WM2
in/outEfficiency BE Wavelength
/nmReferences 2004 Wright Patterson Air Force Base 0.8 7/1.6 6% 1 1 116 [80] 2006 University of Southampton 10.2 4.8/1.2 48% 9.6 1 660 [79] 2009 European Southern Observatory 153 — 85% — 1 120 [77] 2010 OFS Laboratory 81 — 32% — 1 480 [86] 2010 European Southern Observatory 100 2/>1.6 62.5% 0.9 1 120 [87] 2013 Siberian Branch of the Russian Academy of Sciences 3 — 35% — 980 [88] 2013 National University of Defense Technology 119 — 82% — 1 173 [89] 2014 Shanghai Institute of Optics and Fine Mechanics, CAS 12.3 3.2/1.46 82.7% 2.2 1 658 [90] 2015 University of Southampton 6 22/1.9 9% 9.6 1 120 [91] 2015 University of Southampton 19 22.2/5 48% 5.3 1 019 [91] 2016 Soreq Nuclear Research Center 80 14/5.6 53% 3.5 1 020 [92] 2017 Siberian Branch of the Russian Academy of Sciences 10 20/1.2 15.4% 40 954 [93] 2017 Siberian Branch of the Russian Academy of Sciences 17 — 19% — 954 [94] 2017 Siberian Branch of the Russian Academy of Sciences 50 26/2.6 27% 25 954 [94] 2017 Soreq Nuclear Research Center 154 19.0/8 65% 3 1 020 [95] 2018 Soreq Nuclear Research Center 135 7.6/2.5 68% 5.6 1 081 [96] 2018 Siberian Branch of the Russian Academy of Sciences 62 30.0/3 30% 25 954 [97] 2018 Soreq Nuclear Research Center 250 8.4/3.3 60% 3.6 1 080 [98] 2018 Soreq Nuclear Research Center 1 200 8/2.75 85% 7 1 120 [85] 说明:表中 “—” 表示该文献中未提供该项数据 -
主振荡功率放大器(Master Oscillator Power Amplifier, MOPA)结构能够缓解FBG等光纤器件对热损伤阈值与功率损伤阈值的要求,其在RFLs中的运用能够大幅提升输出功率。此外,在RFLs中采用MOPA结构,后向回光远低于振荡器结构,有利于降低后向回光对泵浦激光器的影响。表2和图6分别展示了近年来RFA的输出功率水平。
表 2 近年来高功率拉曼光纤放大器的研究进展
Table 2. Research progress of high-power RFA in recent years
Years Research institute Power
/WM2
in/outEfficiency BE Wavelength
/nmGain type References 2002 University of Southampton 0.05 4.4/— 36% 17.5 1 069 Raman [78] 2012 Jena University 208 —— 87% —— 1 118-
1 130Raman [103] 2013 OFS Laboratory 301 —— 64% —— 1 480 Raman [104] 2014 Shanghai Institute of Optics and Fine Mechanics, CAS 300 —— 70% —— 1 120 Yb-Raman [105] 2014 Beijing University of Technology 14.3 —— 38.5% —— 2 147 Raman [106] 2014 Shanghai Institute of Optics and Fine Mechanics, CAS 1 280 —— 70% —— 1 120 Yb-Raman [102] 2014 National University of Defense Technology 732 —— 82.2% —— 1 120 Yb-Raman [107] 2015 National University of Defense Technology 1 520 —— 75.6% —— 1 120 Yb-Raman [108] 2016 Tsinghua University 3 890 —/1.49 70.9% —— 1 123 Yb-Raman [83] 2018 National University of Defense Technology 528 10.4/4.2 68% 3.8 1 060 Raman [109] 2019 National University of Defense Technology 1 002 9.2/5.1 84% 2.6 1 060 Raman [110] 2019 Tsinghua University 3 700 —/2.18 —— —— 1 123 Yb-Raman [111] 2020 National University of Defense Technology 762.6 6.12/2.24 25% 2.35 1 130 Raman [112] 2020 National University of Defense Technology 2 087 ~13.5/8.9 59.33% —— 1 130 Raman [113] 2021 National University of Defense Technology 2 034 10.5/2.8 79.35% 11.2 1 130 Raman [114] 2021 National University of Defense Technology 3 083 ~11/5.72 78.7% 2.9 1 131 Raman [82] 说明:表中 “—” 表示该文献中未提供该项数据 目前,光纤放大器的最高输出功率是基于掺镱-拉曼混合增益机制产生的。2014年,中国科学院上海光学精密机械研究所的Lei Zhang等首次提出该类型的激光器,并实现了1.3 kW高功率输出 [102]。实验结果如图7所示,信号光和泵浦光被耦合进入掺镱光纤中,通过增加掺镱光纤或者无源光纤的长度,在同一放大级实现泵浦光的放大和拉曼转换。随后,国防科技大学、清华大学等研究机构继续探索掺镱-拉曼混合增益的功率提升潜力,先后实现了1.5 kW和3.89 kW的拉曼激光输出[83, 108]。
然而,上述机制的激光器泵浦方式本质上还属于纤芯泵浦。从拉曼增益产生的过程来看,未能实现从泵浦光到信号光的亮度提升。为进一步探索基于光纤SRS效应的亮度提升潜力,研究人员开始使用具有光束净化效果的GRIN光纤以产生高亮度拉曼激光。近年来,国防科技大学课题组分别基于纤芯泵浦多模GRIN光纤以及包层泵浦三包层光纤等新型技术手段对高功率RFA开展了系列研究。2018年,Yizhu Chen等采用MOPA方案搭建了基于GRIN光纤的全光纤结构RFA[109],实现了528 W的拉曼激光输出,光束质量M2因子由泵浦光的10.4提升为信号光的4.2,对应的亮度提升倍数为3.8。随后三年内,进一步将该类型放大器的输出功率逐渐提升至1 kW、2 kW以及3 kW量级,对应的光束质量M2因子分别为5.1、2.8、7.2(由此计算出输出拉曼激光亮度分别提升了2.6倍、11.2倍以及2.9倍),是目前公开报道基于纯拉曼增益的最高输出功率值[82, 110, 113-114]。2021年,国防科技大学课题组的Chenchen Fan等通过优化泵浦时域的方式有效抑制高阶拉曼光的产生,进一步提升了光束质量,基于GRIN光纤实现了光束质量M2为1.6的千瓦级拉曼激光输出[115],相关实验结构和实验结果如图8所示。此外,国防科技大学课题组的Yizhu Chen等还基于纤芯/内包层/外包层直径为31 μm/55 μm/360 μm的三包层光纤,搭建了首个全光纤结构的包层泵浦RFA,实现了762.6 W的拉曼激光输出,光束质量M2为2.24。
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光谱是激光的一个重要特性。近年来,波长捷变和中心波长拓展也是RFL发展呈现的重要特点。2012年,德国耶拿大学的Rekas等基于空间结构搭建了RFA,对1118~1130 nm光谱范围可调谐的种子进行放大,获得了最大功率208 W的可调谐拉曼激光,对应的拉曼转换效率为87%[103]。2013年,OFS实验室的V. R. Supradeepa等利用W形折射率分布的光纤(W形折射率分布拉曼光纤具有滤波特性、能够有效抑制1500 nm以上的高阶拉曼产生)搭建了全光纤结构的级联RFA,实验结构如图9所示[104],获得了1480 nm的拉曼激光输出,功率301 W,拉曼转换效率为64%(1117~1480 nm),~43% (975~1480 nm)。同年,国防科技大学课题组的Hanwei Zhang等基于75 m纤芯包层直径分别为10/125 μm的无源光纤搭建了全光纤结构的RFLs,通过优化设计FBG的反射率及反射带宽等参数,获得了中心波长为1173 nm的激光输出,功率119 W,拉曼转换效率为82%[89]。
2018年,中国科学院上海光学精密机械研究所的Lei Zhang等通过优化泵浦时域的方式,基于随机分布式反馈拉曼光纤激光器(Random Distributed Feedback Raman Fiber Laser, RRFL)实现了1.1~1.8 μm的超宽光谱范围的级联拉曼激光输出,在1 806 nm处的9阶斯托克斯光功率超过100 W[116]。2019年,印度科学研究所的V. Balaswamy等利用放大自发辐射(Amplified Spontaneous Emission, ASE)光源泵浦RRFL以进一步降低泵浦时域起伏,实现了超高光谱纯度级联拉曼光输出,高阶拉曼波长分别为1390 nm和1480 nm,光谱纯度分别为98%和97.5%[117-118]。
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高功率可见光在激光导星自适应光学系统等领域有重要需求[119]。由于RFLs在很宽范围的近红外波段均能实现高功率输出,对其进行倍频以获得高功率可见光已经成为相关技术领域的研究热点。2004年,日本电气通信大学激光研究中心的Yan Feng等首次通过倍频拉曼光纤激光实现了589 nm激光输出[119]。实验结构如图10所示,泵浦源是波长为1100 nm的双包层掺镱激光器,利用300 m长的掺磷单模光纤作为增益介质实现1178 nm波段激光,在腔外通过三硼酸锂晶体倍频,实现 589 nm激光输出。
此后,科研人员采用类似结构相继实现了477 nm[120]、488 nm[120]、560 nm[121]、620 nm[122]和655 nm[123]等波长的可见光激光。2019年,俄罗斯科学院A. G. Kuznetsov等利用LD泵浦GRIN RFLs,在488 nm得到处0.4 W的激光输出[120],发现与直接用938 nm的LD泵浦所产生的一阶976 nm激光相比,采用915 nm 的LD泵浦产生的二阶拉曼光(976 nm)具有更好的光束质量和更窄的光谱。2019年,伦敦帝国理工学院A. M. Chandran等报道了利用掺磷光纤RFA倍频实现的620 nm激光纳秒脉冲输出,输出功率1.5 W[122]。2021年,中国科学院上海光学精密机械研究所的Shuzhen Cui等利用反向泵浦和窄线宽的FBG抑制RRFL的光谱展宽,实现了1.09 W的589 nm倍频激光输出,倍频效率10.8%[124];同年,该课题组采用级联拉曼嵌套腔结构,获得了10.19 W的589 nm激光输出,效率达18.12% [125]。
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拉曼光纤激光技术的波长灵活性使得它为特殊波长高功率泵浦源提供了新的解决方案。基于RFL产生特殊波段的激光作为泵浦源的泵浦高功率掺铒光纤激光器(Er-doped fiber lasers, EDFLs)[126]、掺铥光纤激光器(Tm-doped fiber lasers, TDFLs)[127]、掺钬光纤激光器(Ho-doped fiber lasers, HDFLs)[128-130]均已有相关报道。
2006年,悉尼大学光纤技术中心S. D. Jackson等将1160 nm输出的RFLs用于泵浦HDFLs[128],可以展现RFLs作为泵浦源的潜力。2012年,OFS实验室V. R. Supradeepa等将输出波长为1480 nm的RFLs用于泵浦EDFLs[126],在1554 nm得到101 W输出,斜率效率达75%。2014年,国防科技大学课题组的Xiong Wang等首次将1150 nm的RFLs用于泵浦2 μm波段的高功率HDFLs[129](实验结构如图11所所示),最终在2 049 nm附近获得了42 W激光输出,且信噪比大于30 dB。同年,该课题组利用两个波长为1 173 nm的RFLs泵浦TDFLs,在1943.3 nm波长处获得了96 W的激光输出[127]。2015年,国防科技大学课题组的Hanwei Zhang等首次利用RRFL泵浦HDFLs,获得了23 W的2 050 nm波长的激光输出[130]。
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2010年,英国阿斯顿大学课题组的Turitsyn等首次系统提出RRFL[131]的概念,分别利用长距离无源光纤中的瑞利散射和SRS提供随机分布式反馈和增益放大,从而实现随机拉曼激光输出。与常规振荡器结构的RFLs相比,RRFL多为开腔结构,这结构上更加简单、输出激光时序上更加稳定[132]。此外,该类型激光器也具有输出波长灵活的特点。因此,RRFL被广泛地运用在测量、成像以及通信等各个领域[133-138]。近年来,RRFL的研究和应用引起国内外同行的广泛关注,在功率提升方面取得了较大进展,相关结果如表3和图12所示。
表 3 近年来RRFL的研究进展
Table 3. Research progress of RRFL in recent years
Years Research institute Power
/WEfficiency Wavelength
/nmReferences 2010 Aston University 0.15 — 1 550 [131] 2015 National University of Defense Technology 124 79% 1 146 [130] 2017 National University of Defense Technology 27 — 996 [139] 2017 National University of Defense Technology 491 — 1120 [140] 2018 Shanghai Institute of Optics and Fine Mechanics, CAS 100.1 38.4%/27.2% 1 000-1 900 [116] 2019 National University of Defense Technology 985 78.9% 1 150 [141] 2021 National University of Defense Technology 1 570 77.5% 1 120 [142] 说明:表中 “—” 表示该文献中未提供该项数据 2015年,国防科技大学课题组的Hanwei Zhang等基于320 m纤芯/包层直径为10/125 μm的传能光纤搭建了全开腔结构的RRFL,获得了百瓦级随机拉曼的激光输出[130]。2019年,该课题组通过使用90 m长、纤芯直径为20 μm的无源光纤作为增益介质(可注入泵浦功率和高阶拉曼阈值得到有效提升),激光器输出功率进一步提升至千瓦水平[141]。目前,RRFL的最高输出功率已经达到1.5 kW[142],相关实验结构如图13所示。研究人员采用采用2 kW泵浦激光过对一段长50 m、纤芯/包层直径为20/400 μm的传能光纤进行泵浦,获得了1.5 kW随机拉曼激光输出,对应的转换效率为77.5%,拉曼抑制比为58.4 dB。
需要注意的是,由于瑞利散射提供的反馈非常微弱,为了降低激光器阈值,上述研究均采用纤芯泵浦常规的阶跃折射率光纤,输出激光亮度无增强效果。2017年,俄罗斯科学院Babin等首次基于GRIN光纤搭建了全光纤结构的RRFL(实验结构如图14所示),通过级联泵浦的方式实现了27 W、中心波长为996 nm的具有亮度增强的RRFL输出,光束质量M2因子为1.6[139]。2021年,国防科技大学课题组的Yizhu Chen等基于一段长120 m、纤芯直径为62.5 μm 的GRIN光纤搭建了全光纤结构的RRFL,实现了输出功率306 W的RRFL输出,光束质量M2由泵浦光的9.25净化至2.35,对应亮度提升倍数为6.1。该结果也是目前GRIN光纤RRFL的最高输出功率值[143]。
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2~5 μm波段中红外激光在生物医学、光谱特征识别、大气遥感、激光雷达、国防等领域有着重要应用。基于软玻璃光纤中的SRS是实现该波段激光的一种有效手段。2007年,加拿大拉瓦尔大学V. Fortin等采用0.8 μm飞秒激光器在氟化物光纤中成功写入FBG[144];2011年,课题组基于氟化物光纤FBG搭建全光纤结构法布里-珀罗(Fabry Perot, F-P)腔,并利用TDFLs进行泵浦,获得了波长为2.19 μm、功率为0.58 W的拉曼激光输出[145],这是首个以氟化物光纤为增益介质的RFLs。2012年,课题组利用更高功率TDFLs进行泵浦,并在末端增加一个在泵浦波长高反的FBG对系统进行了优化,实现了功率为3.7 W的拉曼激光输出,波长为2.2 μm[146]。2013年,加拿大拉瓦尔大学M. Bernier等报道了在硫系光纤中刻入多个FBG构成低损耗F-P腔的RFLs方案[147]。泵浦源是3.01 μm的准连续掺铒氟化物光纤激光器,输出的信号光为3.34 μm,最大平均功率为47 mW,对应的峰值功率为0.6 W;2014年,课题组再次采用F-P腔结构实现两级级联RFLs(泵浦波长仍为3.01 μm),级联拉曼频移产生的二阶拉曼激光波长为3.77 μm,最大平均功率为9 mW,对应峰值功率为112 mW,这是迄今为止在RFLs中获得的最长波长[148]。
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研究人员还将典型的短脉冲产生技术(如调Q、增益开关、锁模和同步泵浦等)应用于RFLs,以实现波长灵活的(超)短脉冲激光[149]。2013年,西班牙纳瓦拉公立大学Bravo 等首次报道了基于主动调Q技术的RFLs,获得了持续时间为 ~1 ns 的稳定拉曼脉冲序列[150]。2015 年,江苏师范大学Yao等采用纳秒调Q光纤激光器泵浦脉冲RFA,实现了最小持续时间为123 ns的稳定拉曼激光脉冲序列[151]。与泵浦脉冲相比,获得的拉曼激光脉冲宽度大大减小,这表明增益开关技术是在RFLs中获得纳秒拉曼脉冲的有效方法。此外,锁模技术也已经在RFLs中得到广泛应用,如基于光调制器的主动锁模[152-153]、基于可饱和吸收体的被动锁模[154-155]以及其他新型被动锁模技术[156-158]。近年来,基于同步泵浦技术的脉冲RFLs研究发展迅速,包括使用光延迟线和光纤展宽器[159-161],调整泵浦源的脉冲参数[162-165]和脉冲RRFL等[166]。
50th anniversary of Raman fiber laser: History, progress and prospect (Invited)
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摘要: 自1972年Roger H. Stolen等人首次基于受激拉曼散射效应在玻璃光纤中实现激光输出以来,拉曼光纤激光技术已经走过了50年的发展历程。文中首先分阶段呈现拉曼光纤激光的发展历程,介绍具有里程碑意义的经典文献和重要技术突破,勾勒出拉曼光纤激光发展的概貌。其次根据拉曼光纤激光的研究现状,整理具有代表性的最新成果;介绍随机分布式反馈拉曼光纤激光、中红外拉曼光纤激光和超快激光等最新研究热点。最后梳理拉曼激光合束、半导体激光直接泵浦和非线性效应耦合新机制等方面的发展趋势。Abstract: The Raman fiber laser (RFL) has been developed for 50 years since the first laser generation in fiber based on stimulated Raman scattering in 1972 by Roger H. Stolen. Firstly, the development history of RFL was presented in stages. Through the introduction on classic milestone literatures standing for the significant technological breakthroughs, the general picture of the development of Raman fiber laser technology could be formed. Secondly, based on the recent status of RFL, the representative advanced achievements were selected, together with the novel research hotspots on the random distributed feedback Raman fiber lasers, middle-infrared Raman fiber lasers and ultra-fast fiber lasers. Finally, the future prospects of RFL were discussed, including the laser beam combination, laser diode directly pumped RFL and new mechanism on interactions among fiber nonlinear optics.
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Key words:
- stimulated Raman scattering /
- Raman fiber laser /
- nonlinear effects /
- power scaling /
- beam quality
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图 3 (a) 1980~2000年OSA和IEEE发表EDFA以及RFA相关的论文以及申请专利数量统计[69];(b) 1994~2003年OFC会议的传输实验的容量-距离乘积[69]
Figure 3. (a) Statistics of papers and patent applications related to EDFA and RFA published by OSA and IEEE from 1980 to 2000[69]; (b) Capacity distance product of transmission experiment of OFC Conference from 1994 to 2003[69]
表 1 近年来拉曼光纤振荡器的研究进展
Table 1. Research progress of Raman fiber oscillator in recent years
Years Research institute Power
/WM2
in/outEfficiency BE Wavelength
/nmReferences 2004 Wright Patterson Air Force Base 0.8 7/1.6 6% 1 1 116 [80] 2006 University of Southampton 10.2 4.8/1.2 48% 9.6 1 660 [79] 2009 European Southern Observatory 153 — 85% — 1 120 [77] 2010 OFS Laboratory 81 — 32% — 1 480 [86] 2010 European Southern Observatory 100 2/>1.6 62.5% 0.9 1 120 [87] 2013 Siberian Branch of the Russian Academy of Sciences 3 — 35% — 980 [88] 2013 National University of Defense Technology 119 — 82% — 1 173 [89] 2014 Shanghai Institute of Optics and Fine Mechanics, CAS 12.3 3.2/1.46 82.7% 2.2 1 658 [90] 2015 University of Southampton 6 22/1.9 9% 9.6 1 120 [91] 2015 University of Southampton 19 22.2/5 48% 5.3 1 019 [91] 2016 Soreq Nuclear Research Center 80 14/5.6 53% 3.5 1 020 [92] 2017 Siberian Branch of the Russian Academy of Sciences 10 20/1.2 15.4% 40 954 [93] 2017 Siberian Branch of the Russian Academy of Sciences 17 — 19% — 954 [94] 2017 Siberian Branch of the Russian Academy of Sciences 50 26/2.6 27% 25 954 [94] 2017 Soreq Nuclear Research Center 154 19.0/8 65% 3 1 020 [95] 2018 Soreq Nuclear Research Center 135 7.6/2.5 68% 5.6 1 081 [96] 2018 Siberian Branch of the Russian Academy of Sciences 62 30.0/3 30% 25 954 [97] 2018 Soreq Nuclear Research Center 250 8.4/3.3 60% 3.6 1 080 [98] 2018 Soreq Nuclear Research Center 1 200 8/2.75 85% 7 1 120 [85] 说明:表中 “—” 表示该文献中未提供该项数据 表 2 近年来高功率拉曼光纤放大器的研究进展
Table 2. Research progress of high-power RFA in recent years
Years Research institute Power
/WM2
in/outEfficiency BE Wavelength
/nmGain type References 2002 University of Southampton 0.05 4.4/— 36% 17.5 1 069 Raman [78] 2012 Jena University 208 —— 87% —— 1 118-
1 130Raman [103] 2013 OFS Laboratory 301 —— 64% —— 1 480 Raman [104] 2014 Shanghai Institute of Optics and Fine Mechanics, CAS 300 —— 70% —— 1 120 Yb-Raman [105] 2014 Beijing University of Technology 14.3 —— 38.5% —— 2 147 Raman [106] 2014 Shanghai Institute of Optics and Fine Mechanics, CAS 1 280 —— 70% —— 1 120 Yb-Raman [102] 2014 National University of Defense Technology 732 —— 82.2% —— 1 120 Yb-Raman [107] 2015 National University of Defense Technology 1 520 —— 75.6% —— 1 120 Yb-Raman [108] 2016 Tsinghua University 3 890 —/1.49 70.9% —— 1 123 Yb-Raman [83] 2018 National University of Defense Technology 528 10.4/4.2 68% 3.8 1 060 Raman [109] 2019 National University of Defense Technology 1 002 9.2/5.1 84% 2.6 1 060 Raman [110] 2019 Tsinghua University 3 700 —/2.18 —— —— 1 123 Yb-Raman [111] 2020 National University of Defense Technology 762.6 6.12/2.24 25% 2.35 1 130 Raman [112] 2020 National University of Defense Technology 2 087 ~13.5/8.9 59.33% —— 1 130 Raman [113] 2021 National University of Defense Technology 2 034 10.5/2.8 79.35% 11.2 1 130 Raman [114] 2021 National University of Defense Technology 3 083 ~11/5.72 78.7% 2.9 1 131 Raman [82] 说明:表中 “—” 表示该文献中未提供该项数据 表 3 近年来RRFL的研究进展
Table 3. Research progress of RRFL in recent years
Years Research institute Power
/WEfficiency Wavelength
/nmReferences 2010 Aston University 0.15 — 1 550 [131] 2015 National University of Defense Technology 124 79% 1 146 [130] 2017 National University of Defense Technology 27 — 996 [139] 2017 National University of Defense Technology 491 — 1120 [140] 2018 Shanghai Institute of Optics and Fine Mechanics, CAS 100.1 38.4%/27.2% 1 000-1 900 [116] 2019 National University of Defense Technology 985 78.9% 1 150 [141] 2021 National University of Defense Technology 1 570 77.5% 1 120 [142] 说明:表中 “—” 表示该文献中未提供该项数据 -
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