基于相位板旋转排布的超快束匀滑方案  

Ultrafast Beam Smoothing Scheme Based on Rotation Arrangement of Phase Plates

作　　者：邹冬岩 熊皓 钟哲强[1] 张彬[1] Zou Dongyan;Xiong Hao;Zhong Zheqiang;Zhang Bin(College of Electronics and Information Engineering,Sichuan University,Chengdu,Sichuan 610065,China)

机构地区：[1]四川大学电子信息学院,四川成都610065

出　　处：《中国激光》2022年第4期51-60,共10页Chinese Journal of Lasers

基　　金：国家科技重大专项(JG2020376);国家自然科学基金(61905157);中国博士后科学基金(2018M643463);中央高校基本科研经费(19XJ0001)。

摘　　要：提出了一种基于相位板旋转排布的束匀滑方案,通过在激光集束中以旋转方式排布具有旋转非对称性的相位板,为集束中各子光光束提供不同的空间相位调制,进而利用存在一定波长差的子光束在靶面的动态干涉,使得焦斑内部散斑在多方向、多维度快速扫动,从而达到在皮秒时间尺度内改善焦斑均匀性的目的。以2×2集束为例,通过建立基于相位板旋转排布的束匀滑方案物理模型,分析了相位板参数、排布方式、激光束相位畸变参数以及空间偏差对束匀滑效果的影响。结果表明,在基于相位板旋转排布的束匀滑方案中,仅需同时加工多套参数相同的相位板,即可降低相位板的设计、加工难度。此外,该方案的束匀滑效果受激光束相位畸变、相位板排布方式以及空间偏差的影响较小。Objective In the inertial confinement nuclear fusion(ICF) facility,the non-uniformity of the target plane irradiation aggravates the instability of various laser plasmas such as magnification into filaments,stimulated Raman scattering,and stimulated Brillouin scattering,and destroys the target pellet symmetry of compression.In order to improve the irradiation uniformity of the target plane,researchers have successively developed a variety of beam smoothing schemes,such as radial smoothing(RS),azimuthal smoothing(AS),dynamic interference smoothing,and the combination of induced spatial incoherence(ISI) and lens array(LA) based on broadband light proposed by Shanghai Institute of Laser Plasma.However,these schemes have some shortcomings.Therefore,there is an urgent need to further develop a more feasible ultrafast beam smoothing scheme with a picosecond time scale.Methods Taking the 2 × 2 beam as an example,by establishing a physical model of the ultrafast beam smoothing scheme based on the rotation arrangement of phase plates,the effects of parameters of phase plates,beam arrangement,spatial wavefront distortion,and spatial deviation of laser beams on beam smoothing are analyzed.Results and Discussions Through calculation and simulation,the effects of parameters of phase plates,beam arrangement,spatial wavefront distortion,and spatial deviation of laser beams on beam smoothing are first investigated,the smoothing effect when the scheme is combined with the traditional beam smoothing scheme is then analyzed,and finally the influence of spatial deviation in the actual system on beam smoothing is studied.The simulation results show that when the peak valley(PV) value of the phase plate is 2λ-3λ,it can not only ensure the beam smoothing effect of the scheme,but also avoid the excessive energy loss caused by wavefront distortion(Fig.4).In addition,changing the arrangement of phase plates has little effect on the smoothing effect of the scheme(Fig.5).When the PV value of phase distortion does not exceed 3λ,the schem

关 键 词：激光光学 惯性约束聚变 相位板旋转排布 束匀滑 加工难度 

分 类 号：TN24[电子电信—物理电子学]