3μm高效率Er∶YAG循环级联脉冲激光器  

3-μm High-Efficiency Er∶YAG Cyclic Cascade Pulse Laser

作　　者：田野[1] 王思博 曲波[1] 朱占达[1,2,3,4] 惠勇凌 雷訇[1,2,3,4] 李强 Tian Ye;Wang Sibo;Qu Bo;Zhu Zhanda;Hui Yongling;Lei Hong;Li Qiang(Institute of Laser Engineering,Faculty of Materials and Manufacturing,Beijing University of Technology,Beijing 100124,China;Beijing Engineering Research Center of Laser Technology,Beijing 100124,China;Beijing Higher Institution Engineering Research Center of Advanced Laser Manufacturing,Beijing 100124,China;Key Laboratory of Trans-scale Laser Manufacturing Technology,Ministry of Education,Beijing 100124,China)

机构地区：[1]北京工业大学材料与制造学部激光工程研究院,北京100124 [2]北京市激光应用技术工程技术研究中心,北京100124 [3]激光先进制造北京市高等学校工程研究中心,北京100124 [4]跨尺度激光成型制造技术教育部重点实验室,北京100124

出　　处：《中国激光》2023年第7期175-181,共7页Chinese Journal of Lasers

基　　金：国家自然科学基金(62075003,62275007);北京市自然科学基金(4202007,KZ202110005010)。

摘　　要：报道了室温下基于循环级联的高效率Er∶YAG中红外脉冲激光器,采用循环级联谐振腔,通过优化晶体长度提高光束交叠效率,获得高效率中红外激光输出。实验中使用两种掺杂浓度(原子数分数分别为25%和10%)的长度为2 mm Er∶YAG晶体作为增益介质,测得波长为2937 nm的中红外激光的输出斜效率分别为37.2%和36.5%,均突破了33.2%的Stokes极限。据我们所知,这是首次在室温下使用较低掺杂浓度(原子数分数为10%)的Er∶YAG晶体获得了超过Stokes极限的高效率3μm中红外激光输出。Objective Mid-infrared lasers at approximately 3μm can be used in many fields such as medical surgery,trace gas detection,remote sensing,and infrared countermeasures.Such laser source can be obtained via Dy^(3+)-,Ho^(3+)-,or Er^(3+)-doped laser active medium.The development of Dy^(3+)-and Ho^(3+)-doped lasers is limited because of the lack of a suitable pump source.In contrast,there is a strong absorption band of Er^(3+)-doped crystals at approximately 970 nm and they can be pumped by well-developed high-power InGaAs LDs.However,the transition of Er^(3+)ions at approximately 3μm wavelength is self-terminating because the lifetime of the initial laser level is considerably shorter than that of the terminal laser level.To overcome this“bottleneck”,Er^(3+)ions with a high atomic fraction of 30%-50%are typically required to depopulate lower laser level~4I_(13/2).The thermal effects increase with increasing doping concentration.Cascading~4I_(13/2)→~4I_(15/2)near-infrared laser emission can achieve a 3-μm-laser output at an extremely low doping concentration but at the expense of reducing the conversion efficiency.In our recent study,it has been proven that the cyclic cascade can improve the efficiency of a 3-μm-laser in Er∶YAG crystals,with a low doping concentration at room temperature.However,the maximum slope efficiency does not exceed 10%.On the basis of the cyclic cascade,improving the slope efficiency is a meaningful attempt.Methods In this study,we theoretically analyzed the two main factors influencing the mid-infrared(MIR)laser slope efficiency in Er∶YAG crystals,namely,quantum efficiency and overlapping efficiency.We analyzed the mechanism of improving the quantum efficiency by a cyclic cascade.For the overlapping efficiency,we simulated the distributions of the pump light and laser mode field and analyzed their influence on the overlapping efficiency.Next,the coating parameters of the cavity mirror were designed according to the relevant characteristic wavelengths in the cyclic cascade process

关 键 词：激光器 Er^(3+)激光器 循环级联 中红外激光器 高效率 

分 类 号：TN248.1[电子电信—物理电子学]