Nonsequential Double Recombination in Intense Laser Fields

A second plateau in the harmonic spectra of laser-driven two-electron atoms is observed both in the numerical solution of a low-dimensional model helium atom and using an extended strong field approximation. It is shown that the harmonics well beyond the usual cut-off are due to the simultaneous recombination of the two electrons, which were emitted during different, previous half-cycles. The new cut-off is explained in terms of classical trajectories. Classical predictions and the time-frequency analysis of the ab initio quantum results are in excellent agreement. The mechanism corresponds to the inverse single photon double ionization process in the presence of a (low frequency) laser field.Comment: 4 pages, RevTeX, v2 with an extended strong field approximation treatment of the process; instead, v1 describes an attosecond control scheme to enhance the proces

Pengaruh Sistem Informasi Akuntansi Penggajian Berbasis Komputer dan Pengendalian Intern Penggajian terhadap Kinerja Karyawan pada Pusat Pendidikan dan Pelatihan Geologi Kemeterian Energi dan Sumber Daya Mineral Bandung

Penelitian ini bertujuan untuk mengetahui apakah sistem informasi akuntansipenggajian berbasis komputer dan pengendalian intern penggajian mempunyaipengaruh positif yang signifikan tehadap kinerja karyawan, serta berapa besarpengaruh sistem informasi akuntansi penggajian berbasis komputer dan pengendalianintern penggajian terhadap kinerja karyawan. Dalam penelitian ini terdapat 3 variabelyaitu sistem informasi akuntansi penggajian berbasis komputer sebagai variabelindependen (Xl), pengendalian intem penggajian sebagai variabel independen (X2) dankinerja karyawan sebagai variable dependen (Y). Metode penelitian yang digunakandalam penulisan skripsi ini adalah deskriptif (desciptive) yang merupakan surveiterhadap 30 orang karyawan yang bekerja pada Pusat Pendidikan dan PelatihanGeologi Bandung. Teknik pengumpulan data dilakukan dengan cara teknik surveimenggunakan instrument kuesioner serta dilengkapi dengan teknik wawancara.Datayang diperoleh dari hasil analisis jawaban kuesioner, kemudian dilakukan pengujianhipotesis dan dianalisis menggunakan korelasi pearson dan koefisien determinasi.Dengan analisis regresi menunjukan besarnya variabel Xl (Sistem Informasi AkuntansiPenggajian Berbasis Komputer ) dengan variabel Y (Kinerja Karyawan) sebesar 0,540variaber X2 ( pengendalian Intern penggajian) dengan variabel Y (Kinerja karyawan)sebesar 0,297 dan 6,186 terdapat hubungan positif yang sangat erat atau dapatdiandalkan,sedangkan tanda positif menunjukkan bahwa adanya hubungan searah.Untuk korelasi determinasi menunjukkan bahwa besarnya sumbangan atau pengaruhsistem informasi akuntansi penggajian berbasis komputer dan pengendalian internpenggajian terhadap kinerja karyawan. Selain itu juga untuk menguji hipotesis denganmenggunakan uji-t, menunjukkan ditolaknya hipotesis nol. Metode analisis datadengan bantuan software SPSS versi 21.0 For Windows.Berdasarkan hasil pengujianstatistik tersebut, maka dapat disimpulkan bahwa terdapat pengaruh positif yangsignifikan yaitu sebesar 40,3 % antara sistem informasi akuntansi penggajian berbasiskomputer dan pengendalian intern penggajian terhadap kinerja karyawan

Nonlinear resonance reflection from and transmission through a dense glassy system built up of oriented linear Frenkel chains: two-level models

A theoretical study of the resonance optical response of assemblies of oriented short (as compared to an optical wavelength) linear Frenkel chains is carried out using a two-level model. We show that both transmittivity and reflectivity of the film may behave in a bistable fashion and analyze how the effects found depend on the film thickness and on the inhomogeneous width of the exciton optical transition.Comment: 26 pages, 9 figure

X-ray emission from a liquid curtain jet when irradiated by femtosecond laser pulses

Laser-based sources of ionizing radiation have attracted considerable attention in the last years for their broad potential applications. However, the stability and robustness of such sources are still issues that need to be addressed. Aiming to solve such problems, we propose a source that uses a liquid jet—rather than a solid—as a target for the production of X-rays. Liquid jets offer always a clean surface for every laser shot which represent a clear advantage over solids. In this work, we present an experimental characterization of the X-ray emission of such targets, and study the efficiency of the process when two temporally delayed pulses are used. According to the obtained results, the X-ray yield is comparable with commonly used targets.Ministerio de Economía y Competitividad FIS2016- 81056-

Buried waveguides in Nd:YLF crystals obtained by femtosecond laser writing under double line approach

In this paper, we present buried waveguides fabricated by fs laser writing in Nd3+ doped YLF crystal under double line approach (Miura et al. in Appl. Phys. Lett. 71:3329–3331, 1997). The waveguides were made by focusing two consecutive optical breakdown tracks (OBT) separated by about 20 μm. To make the optimal OBT, we focused the fs-laser pulses 200 μm below surface at intensities above the OB threshold for the material and controlled the writing speed. The guiding structures were fabricated by using a Chirped Pulse Amplification (CPA) femtosecond (fs) laser system. We chose the optimal writing parameters in order to obtain suitable waveguides, using around 3 μJ energy and writing speed from 15 to 50 μm/s. After optically exploring the waveguides by end-fire coupling, the guiding structures showed good optical performance. Guiding index profiles were retrieved from modal analysis by using BeamProp (RSoft) commercial software. This spatial distribution of the index increment, taking into account a lower refractive barrier on the OBT region plus the compressed region between the tracks, was obtained correctly fitting profiles modes. Finally, optical spectroscopy measurements were also performed in the waveguides. The results showed that the luminescence properties of Nd3+ ions are preserved in the waveguides compared with the values obtained for bulk.This work was partially supported by Agencia Nacional de Promoción Científica y Tecnólogica. (Argentina) under project PICT-2575 and CONICET (Argentina) under project PIP 0394 and by “Ministerio de Educación y Ciencia,” Spain (Grant no FIS2009-09522 and Consolider Program SAUUL CSD2007-00013). D.B. wishes to thank Comisión de Investigaciones Científicas (Bs. As., Argentina) for his student fellowship

Spatial Modulation of linear and quadratic susceptibilities in Lithium Niobate crystals by using femtosecond laser pulses

In this work we present the spatial control of the linear susceptibility (χ1) in Lithium Niobate crystals by means of infrared (800 nm) femtosecond interaction. Diffraction gratings have been performed on the surface (relief) and inside (phase) of these samples by femtosecond laser writing. Also we have performed a spatial control of the quadratic susceptibility (χ 2 ) by direct writing of a pattern of ferroelectric domains on the surface of z cut substrates by using the second harmonic femtosecond pulses (400 nm). Finally, efficient photonic devices for second harmonic generation via quasi phase matching could be obtained following the experimental procedure presented in this work

Anisotropic lattice changes in femtosecond laser inscribed Nd3+:MgO:LiNbO3 optical waveguides

We report on the fabrication and microspectroscopy imaging of femtosecond laser written double-filament based Nd3+ :MgO:LiNbO3 optical waveguides. The waveguiding high refractive-index regions are identified by blueshifts of the Nd3+ ion fluorescence lines with no deterioration in the fluorescence efficiency, whereas filamentary low-index regions are identified by both a Nd3+ line redshift and a fluorescence efficiency reduction. The lattice structural micromodifications at the origin of both waveguide formation and Nd3+ fluorescence changes have been investigated by means of confocal micro-Raman experiments. We have found that the direct laser written filaments are mainly constituted by a large density of defects, together with a marked axial compression perpendicular to the filaments �along the optical c-axis�. Conversely, the high-index waveguiding regions are characterized by a pronounced anisotropic dilatation of the LiNbO3 lattice xy-planes

Three-dimensional numerical simulation of 1GeV/Nucleon U92+ impact against atomic hydrogen

The impact of 1GeV/Nucleon U92+ projectiles against atomic hydrogen is studied by direct numerical resolution of the time-dependent wave equation for the atomic electron on a three-dimensional Cartesian lattice. We employ the fully relativistic expressions to describe the electromagnetic fields created by the incident ion. The wave equation for the atom interacting with the projectile is carefully derived from the time-dependent Dirac equation in order to retain all the relevant terms.Comment: 12 pages and 7 figures included in the tex

Reevaluation of radiation reaction and consequences for light-matter interactions at the nanoscale

In the context of electromagnetism and nonlinear optical interactions damping is generally introduced as a phenomenological, viscous term that dissipates energy, proportional to the temporal derivative of the polarization. Here, we follow the radiation reaction method presented in [G. W. Ford and R. F. O'Connell, Phys. Lett. A, 157, 217 (1991)], which applies to non-relativistic electrons of finite size, to introduce an explicit reaction force in the Newtonian equation of motion, and derive a hydrodynamic equation that offers new insight on the influence of damping in generic plasmas, metal-based and/or dielectric structures. In these settings, we find new damping-dependent linear and nonlinear source terms that suggest the damping coefficient is proportional to the local charge density, and nonlocal contributions that stem from the spatial derivative of the magnetic field and discuss the conditions that could modify both linear and nonlinear electromagnetic responses.Comment: 11 pages, 1 figure, 19 reference