艾里脉冲尤其是啁啾艾里脉冲,由于其具有独特的性质,为此越来越受到人们的广泛关注和研究。但是由于啁啾艾里脉冲的复杂性,至今鲜有关于啁啾艾里脉冲的实验报道。鉴于此,在理论上通过对啁啾高斯脉冲进行调制可以得到啁啾艾里脉冲,并对调制机制及调制后脉冲的传输性质进行一定的研究。研究结果表明,调制后得到的类啁啾艾里脉冲与啁啾艾里脉冲基本相同,而且具有啁啾艾里脉冲的传输性质,这证明了通过对啁啾高斯脉冲进行调制得到啁啾艾里脉冲的可行性。

采用动电位极化曲线和电化学阻抗谱研究了激光选区熔化成形CP-Ti和Ti-5%TiN复合材料在人工模拟体液Hank溶液中的腐蚀性能,结果表明:激光选区熔化成形CP-Ti主要由针状α-Ti相组成,加入的TiN颗粒不仅可以与钛基体形成良好的界面结合,还可以细化α-Ti晶粒并产生更多的晶界;在Hank溶液中,激光选区熔化成形Ti-5%TiN复合材料具有比激光选区熔化成形CP-Ti更好的耐腐蚀性能,这是因为作为微阴极的TiN颗粒均匀地分布在钛基体内,可以加速钛基体的阳极溶解过程,使Ti-5%TiN复合材料能够优先进入钝化状态。

将梯度气压和梯度温度统一归为梯度密度，从而提出了梯度密度的概念，从理论上讨论了梯度密度对于超强飞秒（fs）脉冲成丝和等离子体通道形成和演化过程的影响。进一步提出了理想密度曲线的概念，并且对于各种不同情况下的理想密度曲线进行了计算和分析。在理想密度曲线下传输的脉冲能在避免多丝的情况下得到最大限度的非线性作用和光谱展宽，从而有望使得压缩后得到的脉冲宽度更短。对理想密度曲线下传输的实质进行了分析和解释，指出在理想密度曲线下传输的实质是保持n2Pc的恒定，在避免自聚焦或者电离的情况下，能使得光脉冲光斑半径在保持一定范围内长距离传输，并且形成一种自波导。

运用分步傅里叶法对艾里脉冲的色散效应进行了数值模拟及分析。重点分析了二阶、三阶色散效应同时作用下，艾里脉冲的时域波形传输特性，并讨论了在存在初始啁啾以及弱非线性效应作用的情况下脉冲时域波形变化。结果表明正三阶色散效应将引起脉冲压缩，光强增大；负三阶色散作用将导致脉冲展宽，光强下降。在考虑初始啁啾和非线性效应与色散的共同作用时，发现随着三阶色散作用的增大，脉冲的传输质量下降，也说明了三阶色散的重要性。

通过模拟艾里脉冲在克尔介质中的传输，对色散及初始啁啾对脉冲传输的影响以及传输过程中的一些特性进行了初步研究，并对艾里光束和高斯光束的传输特性进行了对比。对于脉宽为飞秒尺度的超短脉冲，三阶色散效应会导致传输波形发生畸变，使光脉冲的传输质量下降，因此不可忽略。进一步研究了艾里光束在二阶和三阶色散共同存在的情况下脉冲随传输距离的变化，并讨论了初始啁啾对脉冲传输变化的影响。理论研究结果表明，当三阶色散和传输距离为某一定值时，脉冲光强极大增强。

We investigate the angular distribution and average kinetic energy of ions produced during ultrafast laser ablation (ULA) of a copper target in high vacuum. Laser produced plasma (LPP) is induced by irradiating the target with Ti:Sapphire laser pulses of ～50 fs and 800 nm at an angle of incidence of 45o. An ion probe is moved along a circular path around the ablation spot, thereby allowing characterization of the time-of-flight (TOF) of ions at different angles relative to the normal target. The angular distribution of the ion flux is well-described by an adiabatic and isentropic expansion model of a plume produced by solid-target laser ablation (LA). The angular width of the ion flux becomes narrower with increasing laser fluence. Moreover, the ion average kinetic energy is forward-peaked and shows a stronger dependence on the laser pulse fluence than on the ion flux. Such results can be ascribed to space charge effects that occur during the early stages of LPP formation.

通过分段中空光波导对超短脉冲进行光谱展宽，进而压缩获得更窄的飞秒脉冲，是获得周期量级飞秒脉冲的一个简单而有效的方法。对这一方法的最优化问题进行了理论研究和数值模拟。理论计算表明，相等的两段光波导并不是最佳的选择方案，进行优化后的方案在脉冲能量和波形上都会有显著提高。另外，考虑各种物理机制，在两段光波导总长度一定的条件下，适当选取前后两段的长度，可以获得更为理想的脉冲，从而提高脉冲压缩的效率和效果。

We present a numerical study on the evolution of the intense femtosecond pulse propagation in argon by solving the extended nonlinear Schr¨odinger equation which includes the beam diffraction, group velocity dispersion, self focusing, absorption and defocusing due to the electron density, and multiphoton ionization processes. The temporal and spatial profiles and the dynamic picture of the ultrashort pulse propagation in argon under different incident conditions such as initial peak intensity, pressure, beam radius, pulse width, and the focal length are discussed. Because the competition between the self focusing and defocusing effects accompanying with other effects as we mentioned above, we can see the splitting into two or even three peaks of the pulse in the time domain.

The performance of intense Bessel femtosecond pulse propagation in dispersive medium is investigated. Water is chosen as the Kerr medium with large dispersion. We find that within the dispersion length, the temporal profile integrated over the beam radius is controlled mainly by dispersion, whereas the spectral profile is nearly undistorted. We also show the energy flow between different transverse parts of the beam, which provides a reservoir for the intense part of the Bessel beam and extends the nonlinear effect length between the pulse and the Kerr medium as we have previously found in argon.

提出了以硅为基质、高折射率铋化合物作为纤芯的多固体芯集束型光子晶体光纤(PCF)。该类光纤利用全内反射型机制将传输光场约束在高折射率固体棒芯中,并能输出相同强度的光。通过数值模拟分析了集束六芯六角形和集束八芯四方形两种光子晶体光纤的有效模场面积和非线性系数随抽运波长以及纤芯直径的变化规律,证明了这种光纤同时具有等效的高非线性和大的有效模场面积的特性,可以用于实现高功率频率变换。