激光诱导击穿光谱技术以其无需样品预处理、 分析速度快、 能实现多元素同时检测和远程分析等优点已经被广泛应用于诸多领域的物质成分定性或定量分析。 该技术的理论基础是激光诱导等离子体。 对等离子体光谱参数(如光谱谱线强度、 等离子体温度等)的准确测量是利用该技术进行定性或定量分析的前提条件。 实际的实验系统中, 由于仪器本身固有的性能限制, 会造成采集光谱信号的失真, 从而限制等离子体光谱参数的精确测量或计算。 为了克服仪器固有性能的影响, 分析了实验系统所用中阶梯光栅光谱仪和传输光纤的固有性能缺点对光谱信号背景噪声和元素谱线绝对强度的影响, 然后采用剥峰法对光谱信号中存在的锯齿状背景噪声进行扣除, 利用辐射定标光源的标准光谱数据对谱线绝对强度进行校正, 并对比了背景扣除和强度校正对等离子体谱线强度和等离子体温度的影响, 实验表明谱线强度校正对合金钢等离子体380 nm以下的光谱信号具有较大影响, 通过背景扣除和强度校正后, 等离子体温度由13 401.75 K降低至8 980.72 K, 玻尔兹曼平面法求解等离子体温度的拟合决定系数由0.60提高至0.91。 因此在光谱数据处理之前对测量光谱进行背景扣除和强度校正是十分必要的, 为提供可靠地光谱数据进行物质成分定性或定量分析奠定了基础。

利用涡旋光束与锥透镜透射率函数设计相位掩模板，采用平面光照射写入相位掩模板的空间光调制器(SLM)，则在SLM的傅里叶平面上产生了完美涡旋光束，解决了傅里叶平面0级和±1级光谱重叠的问题。提出了一种完美涡旋光束的空间自由调控技术，通过实验分析，明确了空间调控位移与调控因子间的函数关系，调控精度达到了2.25 μm。通过在线调节锥透镜的锥角参数，实现了完美涡旋光束中心亮环半径的自由调控，并得到光束中心亮环半径与锥角的二次函数关系。将波长为532 nm和632.8 nm入射光产生的完美涡旋光束作对比，结果表明，当入射波长较长时，仍可得到较小半径的完美涡旋光束。该研究为完美涡旋光束在微粒操纵、光学信息编码、光学测量及基于轨道角动量的光纤通信等领域的应用提供了新思路。

利用矢量波分析法对分数阶高阶贝塞尔涡旋光束(FBV)的电矢量特性进行了研究。在紧聚焦和非紧聚焦条件下，研究了拓扑荷(TCs)增量为0.1阶、拓扑荷从2.1增到3的过程中，Ex、Ey、Ez三个电场分量强度图的变化情况。进而对比分析了TCs值为整数阶和半整数阶FBV光束在由紧聚焦向非紧聚焦过渡过程中Ex分量强度的变化情况。数值模拟结果表明，紧聚焦和非紧聚焦情况下，三个分量的电场强度分布差异较大，其亮环圆对称性均遭到破坏；非紧聚焦情况下，Ex分量的圆对称性增强，而Ey、Ez分量与紧聚焦条件下的光强分布基本相同；在由紧聚焦向非紧聚焦过渡过程中，Ex分量整数阶TCs光束亮环圆对称性逐渐增强，而半整数阶TCs光束亮环结构基本不变，仅存在缩放关系。

Magnetic reconnection (MR) is a universal physical process in plasma, in which the stored magnetic energy is converted into high-velocity flows and energetic particles. It is believed that MR plays an important role in many plasma phenomena such as solar fare, gamma-ray burst, fusion plasma instabilities, etc.. The process of MR has been studied in detail by dedicated magnetic-driven experiments. Here, we report the measurements of magnetic reconnection driven by Shenguang II lasers and Gekko XVII lasers. A collimated plasma jet is observed along the direction perpendicular to the reconnection plane with the optical probing. The present jet is very different from traditional magnetic reconnection outflows as known in the two-dimensional reconnection plane. In our experiment, by changing the delay of optical probing beam, we measure the temporal evolution of jet from 0.5 ns to 2.5 ns and its velocity around 400 km/s is deduced. Highcollimated jet is also confirmed by its strong X-ray radiation recorded by an X-ray pinhole camera. With the help of optical interferograms we calculate the jet configuration and its density distribution by using Abel inverting technique. A magnetic spectrometer with an energy range from hundred eV up to one MeV is installed in front of the jet, in the direction perpendicular to the reconnection plane, to measure the accelerated electrons. Two cases are considered for checking the acceleration of electrons. The results show that more accelerated electrons can be found in the reconnection case than in the case without reconnection. We propose that the formation and collimation of the plasma jet, and the electron energy spectrum may be possible directly influenced by the reconnection electric field, which is very important for understanding the energy conversion in the process of MR and establishment of the theoretical model. Finally the electron energy spectra of three different materials Al, Ta and Au are also shown in our work. The results indicate that the higher atomic number material can obtain a better signal-noise ratio, which provides some helpful references for our future work.

利用“神光Ⅱ”激光装置的两束激光烧蚀半圆柱壳层靶产生了高速等离子体喷流。喷流的参数由光学和X射线诊断测量。喷流是准直的,在真空中传播。一维流体力学模拟被用来间接地计算喷流的速度。喷流的准直可能来源于高Z等离子体的辐射冷却。由于和年轻恒星喷流具有某些几何相似性,实验室喷流对于在实验室中模拟年轻恒星喷流具有潜在应用。

分别利用1 kHz和200 kHz两种重复频率的近红外飞秒激光，经过低数值孔径的物镜聚焦，空间选择性地辐照KCl晶体，在KCl晶体内部诱导出了一系列色心缺陷。通过飞秒激光辐照前后KCl晶体的吸收光谱分析，明确了飞秒激光照射后KCl晶体内部5种色心的归属，发现色心的浓度随着飞秒激光功率的升高而增长。对吸收光谱的分析表明，两种重复频率的飞秒激光所诱导的色心吸收带相应的峰值略有偏移。认为这是由高重复频率的飞秒激光的热累积效应引起的。理论分析表明，KCl晶体内部的点缺陷和高功率密度飞秒激光与KCl晶体相互作用所诱导的多光子吸收是色心形成的主要原因。