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Ultrafast laser pulses provide unique tools to manipulate magnetization dynamics at femtosecond timescales, where the interaction of the electric field -- such as excitation of spin carriers to non-equilibrium states, generation of…

Laser radiation incident on a ferromagnetic sample produces excited electrons and currents whose spin polarization must not be aligned with the magnetization -- an effect due to spin-orbit coupling that is ubiquitous in spin- and…

Materials Science · Physics 2023-11-03 Oliver Busch , Franziska Ziolkowski , Ingrid Mertig , Jürgen Henk

We investigate the non-linear response and energy absorption in bulk silicon irradiated by intense 12-fs near-infrared laser pulses. Depending on the laser intensity, we distinguish two regimes of non-linear absorption of the laser energy:…

Optics · Physics 2020-04-03 Tzveta Apostolova , Boyan Obreshkov , Iaroslav Gnilitskyi

New features of molecular wires can be observed when they are irradiated by laser fields. These effects can be achieved by periodically oscillating fields but also by short laser pulses. The theoretical foundation used for these…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Sven Welack , Michael Schreiber , Ulrich Kleinekathoefer

When an intense, few-cycle light pulse impinges on a dielectric or semiconductor material, the electric field will interact nonlinearly with the solid, driving a coherent current. An asymmetry of the ultrashort,…

We report on the observation of the nonlinear intensity dependence of the bulk photogalvanic current and photoconductivity in the twisted graphene with small twist angles close to the second magical angle. We show that terahertz radiation…

Mesoscale and Nanoscale Physics · Physics 2021-12-16 S. Hubmann , P. Soul , G. Di Battista , M. Hild , K. Watanabe , T. Taniguchi , D. K. Efetov , S. D. Ganichev

Intense laser-driven nonlinear optical phenomena in two-dimensional (2D) nodal-line semimetals (NLS) exhibit complex mechanisms, particularly in the NbSi$_{x}$Te$_{2}$ material systems characterized by nonsymmorphic symmetry-protected band…

Optics · Physics 2025-08-25 Navdeep Rana , M. S. Mrudul , Amar Bharti , Sucharita Giri , Gopal Dixit

We introduce an ultrafast all-optical approach for efficient chiral recognition which relies on the interference between two low-order nonlinear processes which are ubiquitous in nonlinear optics: sum-frequency generation and third-harmonic…

Optics · Physics 2023-06-09 Josh Vogwell , Laura Rego , Olga Smirnova , David Ayuso

We show that the inter-band absorption of radiation in a 2D Dirac material leads to a direct electric current flowing at sample edges. The photocurrent originates from the momentum alignment of electrons and holes and is controlled by the…

Mesoscale and Nanoscale Physics · Physics 2021-04-21 M. V. Durnev , S. A. Tarasenko

A key issue in the use of high-power mid-infrared (Mid-IR) laser sources for a plethora of applications is the investigation of the exciting laser driven physical phenomena taking place in materials coated with dielectric films. Here, we…

Optics · Physics 2024-05-21 George D. Tsibidis , Emmanuel Stratakis

Sculpting sub-cycle temporal structures of optical waveforms allows one to image and even control electronic clouds in atoms, molecules and solids. Here we show how the transverse spin component arising upon spatial confinement of such…

Optics · Physics 2020-11-17 David Ayuso , Andres Ordonez , Misha Ivanov , Olga Smirnova

We use molecular dynamics simulations with machine-learned atomistic force fields to simulate photoexcitation of BaTiO3 by a femtosecond laser pulse whose photon energy exceeds the optical gap. We demonstrate selective displacive excitation…

Materials Science · Physics 2024-07-30 Fangyuan Gu , Paul Tangney

We introduce the concept of an indirect photonic transition and demonstrate its use in a dynamic delay line to alter the group velocity of an optical pulse. Operating on an ultrafast time scale, we show continuously tuneable delays of up to…

We use an x-ray free-electron laser to study the ultrafast lattice dynamics following above band-gap photoexcitation of the incipient ferroelectric potassium-tantalate, \kto. % We use ultrafast near-UV (central wavelength 266\,nm and 50 fs…

We investigate photoinization, energy deposition, plasma formation and the ultrafast optical breakdown in crystalline silicon irradiated by intense near-infrared laser pulses with pulse duration $\tau \le $ 100 fs. The occurrence of…

Materials Science · Physics 2021-11-24 Tzveta Apostolova , Boyan Obreshkov

Tunneling ionization of an atom in ultrashort laser pulses is considered. When the driving laser pulse is switched-on and -off with a steep slope, the photoelectron momentum distribution (PMD) shows an edge-effect because of the…

Atomic Physics · Physics 2022-07-07 M. Klaiber , Q. Z. Lv , K. Z. Hatsagortsyan , C. H. Keitel

Ultrafast control of electron dynamics in solid state systems has recently found particular attention. By increasing the electric field strength of laser pulses, the light-matter interaction in solids might turn from a perturbative into a…

In the last decade, advancements in attosecond spectroscopy have allowed us to study electron motion dynamics in condensed matter. The access to these electron dynamics and, consequently, its control by an ultrafast light field paves the…

Mesoscale and Nanoscale Physics · Physics 2025-05-12 Mohamed Sennary , Jalil Shah , Mingrui Yuan , Ahmed Mahjoub , Vladimir Pervak , Nikolay Golubev , Mohammed Hassan

Ultrafast manipulation of vibrational coherence is an emergent route to control the structure of solids. However, this strategy can only induce long-range correlations and cannot modify atomic structure locally, which is required in many…

Controlling the longitudinal phase space of high-brightness relativistic electron beams is crucial for advancing a broad spectrum of charged-particle-based instrumentation and scientific frontiers. A generalized method for achieving this…