基于复合腔结构的被动调Q拉曼自锁模激光器  

Passively Q-switched Nd∶YVO_(4)-YVO_(4)-Cr^(4+)∶YAG Self-Mode-Locked Raman Laser Based on Composite Cavity

作　　者：白云涛 丁欣[1,2] 蒋国鑫 雷鹏 孙冰[1,2] 李腾腾 张兴瑞 李翔翔 吴亮[1,2] 张贵忠 姚建铨 Bai Yuntao;Ding Xin;Jiang Guoxin;Lei Peng;Sun Bing;Li Tengteng;Zhang Xingrui;Li Xiangxiang;Wu Liang;Zhang Guizhong;Yao Jianquan(Institute of Laser and Opto-Electronics,School of Precision Instrument and Optoelectronics Engineering,Tianjin University,Tianjin 300072,China;Key Laboratory of Opto-Electronics Information Technology,Ministry of Education,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学精密仪器与光电子工程学院激光与光电子研究所,天津300072 [2]天津大学光电信息技术教育部重点实验室,天津300072

出　　处：《中国激光》2021年第19期42-50,共9页Chinese Journal of Lasers

基　　金：国家自然科学基金(11674242,11674243)。

摘　　要：介绍了一种基于复合腔结构的Nd∶YVO_(4)-YVO_(4)-Cr^(4+)∶YAG被动调Q内腔拉曼自锁模激光器。利用复合腔结构中基频光谐振腔与拉曼光谐振腔相互独立的优势,通过实验验证了受激拉曼散射(SRS)自锁模效应的存在;同时通过合理地控制拉曼光谐振腔的腔长,优化了基频光与拉曼光的模式匹配,大幅提高了拉曼调Q锁模激光的输出功率及转换效率,在17.15 W 808 nm二极管(LD)泵浦功率下获得了调制深度为100%、平均功率为1.23 W的1176 nm拉曼调Q锁模激光输出,光-光转换效率为7.17%,相比于直腔结构提升50%以上。锁模脉冲宽度为125.8 ps,脉冲重复频率为942.9 MHz,调Q包络重复频率约为70 kHz,脉宽为4.25 ns。将拉曼腔前腔镜的曲率半径由100 mm增加至150 mm,对应的拉曼腔长由120 mm增加至180 mm,在相同泵浦功率下获得了调制深度为100%、平均功率为1.19 W的1176 nm拉曼调Q锁模激光输出,转换效率为6.94%,脉冲重复频率降低至675.6 MHz。这些结果说明了该复合腔结构具备在保证输出功率及转换效率的同时,对1176 nm锁模激光的重复频率进行主动调控的能力。Objective High-performance Q-switched mode-locked lasers can achieve high pulse-repetition-frequency(PRF)ultrashort pulse sequences with nanosecond-pulse envelopes,which are of great importance in applications such as laser remote sensing,adaptive optics,and inertial confinement fusion.Because of the clean-up effect,stimulated Raman scattering(SRS)has been regarded as a potential technical approach to achieve high-performance laser output.In particular,with the discovery of the SRS self-mode-locking phenomenon in recent years,Q-switched self-mode-locked Raman lasers with compact structure,high peak power,and high beam quality have gradually been favored by researchers.However,the mechanism of the SRS self-mode-locking phenomenon is relatively complicated,and there are few theoretical studies at present.Although some experiments have reported the SRS self-mode-locking phenomenon with corresponding explanations,most of them have yet to be verified and improved.In addition,the conversion efficiency of self-mode-locked Raman lasers needs to be further improved.Therefore,to solve the above problems,an elaborate folding coupled cavity design was employed.Taking advantage of the folding coupled cavity,the fundamental and Raman cavities can be adjusted independently.Hence,the SRS self-modelocking effect can be verified clearly according to the experimental results,and the mode matching between the fundamental and Raman waves can also be optimized by adjusting the length of the Raman cavity to improve the conversion efficiency of SRS.Methods A schematic diagram of the Nd∶YVO_(4)-YVO_(4)-Cr^(4+)∶YAG passively Q-switched intracavity self-modelocked Raman laser based on a folding coupled cavity is shown in Fig.2.The fundamental resonator consisted of M_(1),M_(2),a Nd∶YVO_(4)crystal,and a Cr^(4+)∶YAG crystal.A common L-shaped Raman cavity(designated by mirror path M_(2)-M_(3)-M_(4))was adopted for the mode matching between the fundamental and Stokes waves.The radius of curvature of M_(1) was 150mm,and the output coupl

关 键 词：激光器 全固态激光器 拉曼激光器 被动调Q锁模激光器 复合腔结构 受激拉曼散射自锁模 

分 类 号：TN248.1[电子电信—物理电子学]