We use finite-difference time-domain modelling to investigate plasma generation induced by multi-photon absorption of intense laser light in dielectrics with tiny inhomogenities. Plasma generation is found to be strongly amplified around nanometer-sized inhomogeneities as present in glasses. Each inhomogeneity acts as the seed of a plasma structure growing against the direction of light propagation. Plasma structures originating from randomly distributed inhomogeneities are found to interact strongly and to organize in regularly spaced planes oriented perpendicularly to the laser polarization. We discuss similarities between our results and nanogratings in fused silica written by laser beams with spatially homogeneous as well as radial and azimuthal polarization.
Interplay of the channel-closing and bound-bound transition resonances in multiphoton ionization and harmonic generation in intense laser pulses
A.V. Gaponov-Grekhov Institute of Applied Physics of the Russian Academy of Sciences（俄罗斯科学院阿·瓦·加波诺夫-格雷霍夫应用物理研究所）；P.N. Lebedev Physical Institute of the Russian Academy of Sciences（俄罗斯科学院列别捷夫物理研究所）；N.I. Lobachevsky State University of Nizhny Novgorod（下诺夫哥罗德洛巴切夫斯基国立大学）
Atomic photoionization dynamics in ultrashort cycloidal laser fields
在二维原子模型中，采用数值模拟的方法研究了同向和反向旋转的圆偏振单色和双色载波包络相位（CEP）稳定超短激光脉冲序列驱动下的超快多光子电离动力学。考虑到由于CEP波动和Gouy相位引起的相位变化，我们的结果准确地再现了最近测量的光电子动量分布[Pengel等人，物理修订信函118，053003（2017），Phys. Rev. A 96，043426（2017）; Kerbstadt等人，10，685（2019），Adv.Phys.X4，1672583（2019）]。计算了坐标和动量空间中复值电子波函数随时间的演化，研究了束缚态和涡旋的形成动力学。不为零的方位几率流密度证明了奇数旋转对称电子波包的涡旋性质。它们的角动量期望值假定为半整数值3.5（共转）和0.5（反转）。波函数的知识使我们能够分析光电离动力学，并验证在以前的实验研究中提出的物理图像。作为一个展望，我们调查如何电子涡旋发展的多光子隧道制度，随着激光强度的增加。
Internal surface plasmon excitation as the root cause of laser-induced periodic plasma structure and self-organized nanograting formation in the volume of transparent dielectric
Measurement of the two-photon absorption cross-section of liquid argon with a time projection chamber
本文报道了在时间投影室（LAr TPC）探测器中激光诱导266 nm液态氩的多光子电离。由激光束产生的电子信号是用于校准和监测下一代大质量LAr TPC的强大工具。我们设计和测试的探测器使我们能够以前所未有的准确度和精度测量LAr的双光子吸收截面：sigma_ex=（1.24 \pm 0.10 stat \pm 0.30 syst）10^{-56} cm ^4 s {-1}。
