超强激光加速产生的高能质子束源在基础物理研究、材料科学、生物医疗等领域具有广泛应用前景。基于激光聚变研究中心的SILEX-II装置，开展了高对比度飞秒激光驱动纳米刷靶质子加速实验研究。采用等离子体镜技术进一步提升激光对比度，有效降低了预脉冲对纳米刷靶结构的影响。相比于平面靶，采用纳米刷靶质子截止能量提高到1.5倍，质子束产额增加近一个量级，成功验证了超高功率密度下纳米刷靶对激光离子加速的增强效果，并且有效提升了质子束空间分布的均匀性。研究结果为高品质质子束源的产生和应用提供了技术途径。

The characteristics of plasmas play an important role in femtosecond laser filament-based applications. Spectroscopic analysis is used to experimentally investigate the plasma density and its temperature of the air filament under different pulse repetition rates. In our experiments, the measured average plasma density of the filament is 1.54×1017cm-3 and the temperature of the plasma is about 5100 K under 100 Hz pulse repetition rate. The plasma density decreases to 1.43×1017cm-3 and the temperature increases to 6230 K as the pulse repetition rate increases to 1000 Hz. The experimental observation agrees with the numerical simulation by solving the nonlinear Schrödinger equations with repetition rate related “low density hole” correction.

A cylindrical Öffner stretcher based on ternary reflector (COSTER) is proposed and analyzed. Compared with the traditional Öffner stretcher, the COSTER has no off-axis aberration in the multipass configuration, and the output laser of COSTER has lower spectral phase noise and higher temporal contrast in the far field. The COSTER is quite suitable to be used in multi-petawatt laser facilities, and it might be the preferred stretcher configuration for ultrafast and ultra-intense lasers.

基于棱镜对的单元件干涉可以获得透射物体的相位信息，即数字全息，具有结构紧凑、干涉条纹稳定、测量精度高等优点。采用光线追迹方法，综合考虑了棱镜对的方位角旋转、斜面偏心等参数，建立了光线追迹等效模型，仿真了数字全息干涉条纹，给出了条纹密度变化及倾斜的解析表达式。针对单模和多模光纤等微结构光学元件，获得了干涉数字全息图，并反演出其折射率分布。搭建了显微成像单元件干涉实验装置，获得了实际测量干涉图样，实验与仿真结果一致，证明了本模型的有效性。

为实现惯性约束聚变（ICF）内爆燃烧停滞阶段过程中最大压缩时刻的冷燃料面密度分布测量，设计了包含字母客体与针孔阵列的照相客体，通过同一发相同视角测量源分布与客体照相技术，首次建立了皮秒激光驱动的高能X射线源编码照相技术。通过星光III实验研究，基于W丝阵靶照相的反演图像空间分辨率5.4 μm±0.7 μm；激光到X射线（50～200 keV）的能量转换效率，W丝阵靶5.4×10⁻⁴，与传统Au单丝靶的转换效率（4.8×10⁻⁴）一致。基于源编码照相解决了传统皮秒激光背光照相中空间分辨率与光源亮度不能兼顾的困难，为强背景干扰下提供高信噪比、高分辨率的ICF靶丸压缩背光图像提供了重要照相方式。

The temporal evolutions of electron density and plasma diameter of 1 kHz femtosecond laser filament in air are experimentally investigated by utilizing a pump-probe longitudinal diffraction method. A model based on scalar diffraction theory is proposed to extract the spatial phase shift of the probe pulse from the diffraction patterns by the laser air plasma channel. The hydrodynamic effect on plasma evolution at 1 kHz filament is included and analyzed. The measured initial peak electron density of ∼1018cm-3 in our experimental conditions decays rapidly by nearly two orders of magnitude within 200 ps. Moreover, the plasma channel size rises from 90 µm to 120 µm as the delay time increases. The experimental observation is in agreement with numerical simulation results by solving the rate equations of the charged particles.