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Present study investigates the THz field generation from laser beat wave interaction with spherical nanoparticles (NPs) in presence of external magnetic field. A cluster of electrons and ions creates during laser interaction with spherical NPs and surface plasmon oscillations generate at surface of spherical cluster with characteristic frequency of ω p / 3 . Oscillatory current produces at beat-wave frequency (ω = ω 1 - ω 2) under the influence of laser imparted ponderomotive force. Oscillatory nonlinear current (J NL ) induces electromagnetic field (E THz / A 0) in THz frequency range. Field decentred (FDC) parameter δ is introduced in laser field profile that redistributes the laser energy in space; external magnetic field is applied in transverse direction. THz field amplitude is estimated with respect to terahertz frequency under the variation of FDC parameter δ , Magnetic field strength (B) and amplitude of the density perturbation (n q / n 0) . THz amplitude enhances significantly in presence of magnetic field with multiple resonance. Also, damping mechanism in plasmon oscillations of NPs can be controlled using laser intensity redistribution in polarization direction. [ABSTRACT FROM AUTHOR]

The beam self-cleaning phenomenon is theoretically predicted by the two-dimensional nonlinear Schrödinger equation, which describes self-focusing, and is observed in the case of femtosecond laser filamentation in the collimated regime of propagation. However, the impact of external focusing on the self-cleaning has not been investigated so far. In this paper we systematically study this impact in a wide range of focusing conditions. We show that the energy range, in which self-cleaning can be observed, shrinks monotonically with the numerical aperture growth at some point vanishing at all. [ABSTRACT FROM AUTHOR]

The paper presents the results of research investigating the possibility of applying laser cleaning for controlled layer-by-layer removal of iron corrosion from gilded silver foil on a medieval nomad's belt pad. Lasers irradiated at the wavelengths of 355, 532, 1064 nm, 2.97, 10.6 μm were tested. A comparison of pulse durations of 100 μs, 100, 8, 6 ns, 75 ps, 100 fs were conducted. Corrosion samples were irradiated in various media: air, argon atmosphere, water, ethanol, engine oil, glycerin. In all of these cases removing of material occurred, but it was accompanied by surface blackening due the burnt organics and to thermal transformation of the goethite and lepidocrocite into magnetite. The best results from the point of view of achieving delicate cleaning and minimal conversion of goethite to magnetite were obtained by the Ti:Sa laser with a 100 fs pulse duration. [ABSTRACT FROM AUTHOR]

Retraction Note to: Optical and Quantum Electronics (2022) 54:684 https://doi.org/10.1007/s11082-022-04091-y The publisher has retracted this article and removed its contents because it was published due to an administrative error. Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. [Extracted from the article]