摘要
高功率特殊波段激光在钠信标、激光测距、激光雷达、自由空间通信等领域具有重要的应用价值。目前,基于受激拉曼散射(stimulated Raman scattering, SRS)的拉曼激光器及放大器已经被证实为拓展激光波段和功率的有效途径。不同于基于粒子数反转激光器在产生和放大过程中需匹配激光增益介质固有的吸收和发射谱,SRS过程理论上能够在其拉曼增益介质透过光谱的全范围内工作,故只需要相互作用光束的频率差满足拉曼增益介质的固有频移,便可实现光束之间的能量直接转移。因此,拉曼放大技术能够利用常规波段的泵浦光对特殊波段的种子光进行放大,从而实现高功率、大能量、高光束质量的特殊波段激光输出。该方法具备波长选择灵活、结构简单、功率拓展性强等优点,近年来已经在钠信标光源等领域得到了应用。文中综述了高功率自由空间拉曼放大技术的主要原理、特性和研究进展,并对其发展趋势和应用前景进行了展望。
Significance Lasers with special wavelengths,high power,and high beam quality have significant applications in the fields such as sodium guide star,laser ranging,and free-space communication.One of the effective approaches to extend the spectral range of lasers is based on stimulated Raman scattering(SRS),which can amplify Stokes beam with a desired wavelength using conventional pump sources.This method can produce highpower and high-quality lasers with special wavelengths,and has advantages such as flexible wavelength selection,simple structure,and strong power scalability.In recent years,SRS-based amplifiers have been applied to generate sodium guide star laser sources,and have potential for further development in other areas.This article reviews the main principles,characteristics,and research progress of high-power free-space Raman amplification technology,and discusses its future trends and application prospects.Progress Currently,the commonly used gain media for Raman amplifiers include gases and crystals.Gas Raman media have advantages such as a large Raman frequency shift,low self-focusing threshold,low optical coupling wave loss,and almost unlimited size.However,they also have disadvantages such as low gain,large volume,and susceptibility to optical breakdown.Compared to gas Raman media,crystal Raman media have advantages such as high Raman gain coefficient,good thermal conductivity,stable performance,and easy miniaturization.However,there are still bottlenecks in the output power and energy of crystalline Raman amplifiers due to factors such as crystal size and damage threshold.Beam combination based on Raman amplification is also an important way to break through the power bottleneck of a single beam and achieve power scaling.This method has advantages such as simple structure,flexible design,and high expandability,and is expected to be further developed and applied in the field of high-power special wavelength lasers.The parameters of gas Raman amplifiers with free-space structures are summarized(Tab.1).At present,the peak laser power output has reached the megawatt level,and the single pulse energy has reached the joule level.The experimental parameters of some crystal Raman amplifiers are summarized (Tab.2). The pulse width of crystal Ramanamplifiers is mainly in the nanosecond, picosecond, and femtosecond levels, with peak power reaching thegigawatt level and single pulse energy reaching the millijoule level.Conclusions and Prospects In recent decades, Raman amplifiers in free space have made many outstandingachievements in the field of high-power special wavelength lasers. However, the output power of Ramanamplifiers is still limited by factors such as the Raman medium and amplifier structure. To overcome theselimitations, future developments in Raman amplification technology will focus on developing new Raman media,optimizing the preparation technology of large-size Raman crystals, improving the conversion efficiency ofRaman amplifiers, and expanding the beam combination structure of high-power Raman lasers. In the future,Raman amplification technology is expected to achieve even greater results in the field of high-power specialwavelength lasers.
作者
白振旭
郝鑫
郑浩
陈晖
齐瑶瑶
丁洁
颜秉政
崔璨
王雨雷
吕志伟
Bai Zhenxu;Hao Xin;Zheng Hao;Chen Hui;Qi Yaoyao;Ding Jie;Yan Bingzheng;Cui Can;Wang Yulei;Lv Zhiwei(Center for Advanced Laser Technology,Hebei University of Technology,Tianjin 300401,China;Hebei Key Laboratory of Advanced Laser Technology and Equipment,Tianjin 300401,China)
出处
《红外与激光工程》
EI
CSCD
北大核心
2023年第8期38-50,共13页
Infrared and Laser Engineering
基金
国家自然科学基金项目(61927815,62075056)
天津市自然科学基金项目(22JCYBJC01100)
量子光学与光量子器件国家重点实验室开放课题项目(KF202201)
河北工业大学基本科研业务费项目(JBKYTD2201)。
关键词
受激拉曼散射
激光
放大器
脉冲
组束
stimulated Raman scattering
laser
amplifier
pulse
beam combination
