基于束间动态干涉的快速匀滑新方法  

Untrafast smoothing scheme based on dynamic interference structure between beamlets of laser quad

作　　者：熊皓 钟哲强[1] 张彬[1] 隋展[2] 张小民[2] Xiong Hao;Zhong Zhe-Qiang;Zhang Bin;Sui Zhan;Zhang Xiao-Min(College of Electronics and Information Engineering,Sichuan University,Chengdu 610065,China;China Academy of Engineering Physics,Mianyang 621900,China)

机构地区：[1]四川大学电子信息学院,成都610065 [2]中国工程物理研究院,绵阳621900

出　　处：《物理学报》2020年第6期115-123,共9页Acta Physica Sinica

基　　金：国家重大专项应用基础项目(批准号:JG2018115,JG2018152,JG2017149);中国博士后科学基金(批准号:2018M643463);国家自然科学基金(批准号:61905167);四川省科技计划资助项目(批准号:2018JY0553);科技部创新人才推进计划重点领域创新团队项目(批准号:2014RA4051)资助的课题~~

摘　　要：针对高功率激光装置中靶面辐照均匀性的高要求,提出了一种利用束间动态干涉改善辐照均匀性的快速匀滑方法.基本原理是利用共轭相位板阵列对存在一定波长差的多束激光附加相位调制,从而使各子束在远场两两相干叠加以产生动态的干涉图样,进而引起焦斑内部散斑的动态扫动,在ps时间内抹平不均匀性.以典型惯性约束聚变装置中的激光集束为例,通过建立基于束间动态干涉的快速匀滑物理模型,定量分析了相位板类型、相位调制幅度和束间波长差等因素对焦斑动态干涉图样的影响及规律,进而对其束匀滑特性进行了讨论.结果表明,基于束间动态干涉的快速匀滑方法可以有效地实现多方向、多维度的焦斑内部散斑快速扫动,且通过与传统束匀滑技术的联用,可以在更短的时间内达到更好的焦斑均匀性.Aiming at the high requirements for illumination uniformity on the target in laser-driven inertial confinement fusion(ICF)facilities,an ultrafast smoothing method based on dynamic interference structure between beamlets of a laser quad is proposed.The basic principle of this scheme is to use a conjugate phase plate array to add the conjugate phase modulation to the multiple beamlets of a laser quad with a certain wavelength difference.Consequently,every two beamlets are coherently superposed in the far field to generate a dynamic interference pattern,resulting in the fast redistribution of the speckles introduced by continuous phase plate inside the focal spot and further improving the illumination uniformity on the target on a picosecond timescale.The coherent beamlets with a certain wavelength difference can be generated by using a broadband seed laser.Taking the laser quad of the typical ICF facilities for example,the physical model of the ultrafast smoothing method based on dynamic interference structure of beamlets is built up.The influences of the phaseplate type,the peak-to-valley value of the phase modulation and the wavelength difference between the beamlets are analyzed quantitatively,and the smoothing characteristics of the focal spot are discussed in detail and compared with those from the traditional temporal smoothing scheme such as smoothing by spectral dispersion.The results indicate that the directions of the moving speckles in the focal spot are determined by the phase-plate type.However,the required time to achieve stable illumination uniformity,i.e,the decay time,is determined by the wavelength difference between the beamlets.Moreover,the illumination uniformity on the target becomes better with the increase of peak-to-valley value of the phase modulation at first and then remains almost the same.Thus,the ultrafast smoothing method based on dynamic interference structures with well-designed phase arrays and wavelength combinations of the beamlets can realize the multi-directional and multi-dim

关 键 词：惯性约束聚变 动态干涉 束匀滑 共轭相位板 

分 类 号：TL632[核科学技术—核技术及应用]