Study of pico second movie of plasma interaction with optical vortex and particle acceleration

1)利用螺旋相移器产生超短脉冲光涡旋：在玻璃衬底上涂覆16阶图案化的SiO* 制成螺旋相移器。结果表明，相位分布与计算全息图预测的相位分布基本一致，并成功地获得了光学涡旋（拓扑荷为1的拉盖尔-高斯光束）。2）亚皮秒时间分辨率成像：对130 fs超短脉冲钛宝石激光进行倍频。利用该紫外光脉冲构建了光学探针系统，并利用阴影照相和干涉技术对短寿命等离子体进行了测量。利用该系统对超短脉冲激光的传输和等离子体形成的动力学过程进行了观测，并研究了它们与激光相位/偏振分布的关系。3）激光纵向电场的产生：线偏振光被转换成轴对称偏振（径向偏振和方位角偏振），效率大于90%，使用基于液晶的旋光的偏振分布板。在0.45MW径向偏振Nd：YAG激光焦斑附近观察到10 ~*V/m的纵向电场。4）利用光学涡旋和径向偏振加速粒子：将0.5- 1 TW的钛宝石激光脉冲聚焦到固体或气体靶上。测量的电子能谱表明，这些特殊的激光模式可以增加前向加速电子的数量，特别是在高能分量。5）粒子模拟：新开发了一个粒子模拟程序，用于分析相位/极化分布所引起的影响。计算结果表明，圆偏振拉盖尔-高斯光束的合成大大增加了高能电子的数量。

1) Generation of ultra-short-pulse optical vortex using spiral phase shifter: A spiral phase shifter was fabricated by coating a 16-steppatterned SiO* onto a glass substrate. The phase distribution was in good agreement with that predicted by the computed hologram, and then an optical vortex (Laguerre-Gaussian beam with a topological charge of 1) was successfully obtained.2) Imaging with sub-ps time resolution: A 130-fs ultra-short Ti: sapphire laser pulse was frequency doubled. Then optical probe system was constructed using this UV pulse for measuring short-life plasmas by shadowgraphy and interferometer techniques. The propagation of ultra-short-pulse laser light and the dynamics of plasma formation were observed using this probing system, and their dependence on laser phase/polarization distributions was studied.3) Generation of longitudinal electric field from laser: A linearly polarized light was converted to axially symmetric polarization (radial polarization and azimuthal polarization) with an efficiency greater than 90% using a polarization distributed plate based on an optical rotatory of liquid crystal. A longitudinal electric field of 10*V/m was observed near a focal spot of 0.45-MW radially polarized Nd: YAG laser. Thus 0.1TV/m can be realized using a TW class high power laser.4) Particle acceleration with optical vortex and radial polarization: Ti: sapphire laser pulse of 0.5-1TW was focused onto a solid or gaseous target. The measured electron spectra suggest that these special laser modes can enhance the amount of forward accelerated electrons especially in high energy component.5) Particle simulation: A particle simulation code has been newly developed for the analysis of the effects caused by the phase/polarization distribution. This code showed that the substantial increase of high-energy electrons for combining the Laguerre-Gaussian beam with circular polarization.