高气压同位素CO_(2)皮秒激光脉冲放大输出特性理论研究  

Theoretical Research on Output Characteristics of High⁃Pressure Isotope CO_(2)Picosecond Pulse Laser Amplification

作　　者：叶静涵 朱子任 白进周 刘羽 谭荣清 郑义军 苏新军 Ye Jinghan;Zhu Ziren;Bai Jinzhou;Liu Yu;Tan Rongqing;Zheng Yijun;Su Xinjun(Aerospace Information Research Institute,Chinese Academy of Sciences,Beijing 100094,China;School of Electronic,Electrical and Communication Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Science and Technology on Particle Transport and Separation Laboratory,Tianjin 300180,China)

机构地区：[1]中国科学院空天信息创新研究院,北京100094 [2]中国科学院大学电子电气与通信工程学院,北京100049 [3]粒子输运与富集技术国家级重点实验室,天津300180

出　　处：《中国激光》2023年第11期216-226,共11页Chinese Journal of Lasers

基　　金：粒子输运与富集技术国防科技重点实验室基金(QT210005)。

摘　　要：为了克服高气压CO_(2)激光脉冲放大器增益谱线调制效应、平滑增益谱线包络以及减少次级脉冲输出,笔者以多种CO_(2)同位素混合物为工作介质,建立了超短CO_(2)脉冲放大模型,模拟了不同中心波长的长波皮秒激光脉冲注入不同气压、不同比例CO_(2)同位素的高气压CO_(2)激光放大器后的增益谱线特性和脉冲输出特性。模拟结果表明:在气压为5 bar、^(13)C和^(18)O原子占比均为50%的条件下,10.591μm附近的增益谱调制度为19.65%,R支较P支增益谱调制度降低了约40%,较好地抑制了次级脉冲输出。在气压为10 bar的条件下,对脉宽为0.3 ps、能量为0.01 J的种子光进行模拟放大,结果显示:在9μm波段,采用^(12)C和^(13)C的6种CO_(2)同位素放大的激光脉宽相比采用^(12)C的3种CO_(2)同位素放大的激光脉宽压缩了28.14%,拖尾能量占比下降了46.37%;在10μm波段,采用^(12)C和^(13)C的6种CO_(2)同位素放大的激光脉宽相比采用^(13)C的3种CO_(2)同位素放大的激光脉宽压缩了23.26%,拖尾能量占比下降了40.06%。Objective Recently,high-pressure CO_(2)laser amplifiers have become an important research direction for chirped pulse amplification,multi-stage MOPA(master oscillator power amplifier)oscillator amplifier,and high-energy laser systems because of their large gain volume,wide gain line width,smooth gain spectrum,and the ability to output TW lever pulse near 10μm.These amplifiers have important applications in laser isotope separation,laser-driven particle acceleration,laser-induced nuclear fusion,etc.When the gas pressure is higher than 10 bar,the gain spectrum is quasi-continuous with a bandwidth of more than 1 THz,which can amplify picosecond pulses.However,the periodic frequency modulation of the gain spectrum generated by rotating energy-level spacing limits the amplification effect.In the time domain,a single input pulse splits into a series of pulses,which affects pulse extraction and energy amplification.Limited by the high-voltage pulse discharge pumping technology,the pressure cannot be infinitely increased to eliminate pulse splitting.The difference in quality of isotopes shifts the frequency of the central spectral line such that several discrete spectra are mixed into a smooth continuous spectrum,overcoming the periodic spectral modulation of the gain spectral line and amplifying picosecond pulses without generating secondary pulses.Methods The output characteristics of a long-wave infrared picosecond pulse,amplified using a CO_(2)amplifier,were numerically simulated.By fully considering the transitions of regular,sequence,and hot bands,the pumping/relaxation dynamics of the laser energy level were modeled.Spectral data were mainly obtained from the latest version of the HITRAN 2016 database.To determine the optimal isotope ratio,analyze the amplified output of different bands,and compare the influence of pressure broadening on pure^(12)C^(16)O_(2)and mixed isotopes,we calculate the output characteristics of^(12)C^(16)O_(2),^(12)C^(16)O^(18)O,^(12)C^(18)O_(2),^(13)C^(16)O_(2),^(13)C^(16)O^(18)O,^(13)C^(

关 键 词：激光光学 CO_(2)激光放大器 CO_(2)同位素 增益谱平滑 皮秒脉冲 

分 类 号：TN248.2[电子电信—物理电子学]