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High-harmonic generation (HHG) is a nonlinear process in which a strong driving field interacts with a material, resulting in the frequency up-conversion of the driver into its high-order harmonics. This process is highly sensitive to the…

Quantum Physics · Physics 2025-07-04 J. Rivera-Dean , P. Stammer , M. F. Ciappina , M. Lewenstein

We present theoretical investigations of high-order harmonic generation (HHG) resulting from the interaction of noble gases with localized surface plasmons. These plasmonic fields are produced when a metal nanoparticle is subject to a…

Generation of even-order optical harmonics requires noncentrosymmetric structures being conventionally observed in crystals lacking the center of inversion. In centrosymmetric systems, even-order harmonics may arise, e.g., at surfaces but…

We study high-order harmonic generation in aligned molecules close to the ionization threshold. Two distinct contributions to the harmonic signal are observed, which show very different responses to molecular alignment and ellipticity of…

Atomic Physics · Physics 2011-09-16 H. Soifer , P. Botheron , D. Shafir , A. Diner , O. Raz , B. D. Bruner , Y. Mairesse , B. Pons , N. Dudovich

Recent years have witnessed significant developments in the study of nonlinear properties of various optical materials at the nanoscale. However, in most cases experimental results on harmonic generation from nanostructured materials are…

In this paper we show that it is possible to structure the longitudinal polarization component of light. We illustrate our approach by demonstrating linked and knotted longitudinal vortex lines acquired upon non-paraxially propagating a…

Optics · Physics 2018-04-19 F. Maucher , S. Skupin , S. A. Gardiner , I. G. Hughes

This work theoretically investigates high-order harmonic generation in rare gas atoms driven by two temporally delayed ultrashort laser pulses. Apart from their temporal delay, the two pulses are identical. Using a single-atom model of the…

The dynamics of electrons in counter-propagating, circularly polarized laser beams are shown to exhibit attractors whose ability to trap particles depends on the ratio of the beam intensities and a single parameter describing radiation…

Plasma Physics · Physics 2016-07-11 J. G. Kirk

This paper presents the method for the first time to generate intense high-order optical vortices that carry orbital angular momentum in the extreme ultraviolet region. In three-dimensional particle-in-cell simulation, both the reflected…

We present theoretical studies of high-order harmonic generation (HHG) produced by non-homogeneous fields as resulting from the illumination of plasmonic nanostructures with a short laser pulse. We show that both the inhomogeneity of the…

Atomic Physics · Physics 2012-04-27 M. F. Ciappina , J. Biegert , R. Quidant , M. Lewenstein

We present studies of high-order harmonic generation (HHG) at laser intensities well above saturation. We use driving laser pulses which present a particular electron dynamics in the turn-on stage. Our results predict an increasing on the…

Atomic Physics · Physics 2015-06-19 J. A. Pérez-Hernández , M. F. Ciappina , M. Lewenstein , A. Zaïr , L. Roso

High harmonic generation traditionally combines ~100 near-infrared laser photons, to generate bright, phase matched, extreme ultraviolet beams when the emission from many atoms adds constructively. Here we show that by guiding a…

We study high-order harmonic generation (HHG) from aligned molecules in strong elliptically polarized laser fields numerically and analytically. Our simulations show that the spectra and polarization of HHG depend strongly on the molecular…

Atomic Physics · Physics 2021-05-19 F. J. Sun , C. Chen , W. Y. Li , X. Liu , W. Li , Y. J. Chen

Optical modulation of high-harmonics generation in solids enables the detection of material properties such as the band structure and promising new applications such as super-resolution imaging in semiconductors. Various recent studies have…

The interaction of intense mid-infrared laser fields with atoms and molecules leads to a range of new opportunities, from the production of bright, coherent radiation in the soft x-ray range to imaging molecular structures and dynamics with…

We observe the generation of high harmonics in the plane perpendicular to the driving laser polarization and show that these are driven by the spin-orbit interaction. Using R-Matrix with time-dependence theory, we demonstrate that for…

High-order harmonic generation from atomic systems is considered in the crossed fields of a relativistically strong infrared laser and a weak attosecond-pulse train of soft x-rays. Due to one-photon ionization by the x-ray pulse, the…

Atomic Physics · Physics 2009-11-13 Michael Klaiber , Karen Z. Hatsagortsyan , Carsten Müller , Christoph H. Keitel

We demonstrate a new high-order harmonic generation mechanism reaching the `water window' spectral region in experiments with multi-terawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving uJ/sr…

Thermotropic liquid crystals are versatile optical materials that exhibit a state of matter intermediate between liquids and solids. Their properties can change significantly with temperature, pressure, or other external factors, leading to…

High-order frequency mixing in graphene using a two-color radiation field consisting of the fundamental and the second harmonic fields of an ultrashort linearly polarized laser pulse is studied. It is shown that the harmonics originated…

Mesoscale and Nanoscale Physics · Physics 2022-05-25 Hamlet K. Avetissian , Garnik F. Mkrtchian , Andreas Knorr