Terahertz radiation driven by two-color laser pulses at near-relativistic intensities: Competition between photoionization and wakefield effects

Abstract We numerically investigate terahertz (THz) pulse generation by linearly-polarized, two-color femtosecond laser pulses in highly-ionized argon. Major processes consist of tunneling photoionization and ponderomotive forces associated with transverse and longitudinal field excitations. By means of two-dimensional particle-in-cell (PIC) simulations, we reveal the importance of photocurrent mechanisms besides transverse and longitudinal plasma waves for laser intensities >1015 W/cm2. We demonstrate the following. (i) With two-color pulses, photoionization prevails in the generation of GV/m THz fields up to 1017 W/cm2 laser intensities and suddenly loses efficiency near the relativistic threshold, as the outermost electron shell of ionized Ar atoms has been fully depleted. (ii) PIC results can be explained by a one-dimensional Maxwell-fluid model and its semi-analytical solutions, offering the first unified description of the main THz sources created in plasmas. (iii) The THz power emitted outside the plasma channel mostly originates from the transverse currents.

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Cylindrically and non-cylindrically symmetric expansion dynamics of tin microdroplets after ultrashort laser pulse impact

Applied Physics A ◽

10.1007/s00339-020-04207-9 ◽

2021 ◽

Vol 127 (2) ◽

Author(s):

Tiago de Faria Pinto ◽

Jan Mathijssen ◽

Randy Meijer ◽

Hao Zhang ◽

Alex Bayerle ◽

...

Keyword(s):

Laser Pulse ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Droplet Deformation ◽

Cylindrically Symmetric ◽

Linearly Polarized ◽

Particle Hydrodynamics ◽

Deformation Dynamics ◽

Smoothed Particle ◽

Asymmetric Shock

AbstractIn this work, the expansion dynamics of liquid tin micro-droplets irradiated by femtosecond laser pulses were investigated. The effects of laser pulse duration, energy, and polarization on ablation, cavitation, and spallation dynamics were studied using laser pulse durations ranging from 220 fs to 10 ps, with energies ranging from 1 to 5 mJ, for micro-droplets with an initial radius of 15 and 23 $$\upmu$$ μ m. Using linearly polarized laser pulses, cylindrically asymmetric shock waves were produced, leading to novel non-symmetric target shapes, the asymmetry of which was studied as a function of laser pulse parameters and droplet size. A good qualitative agreement was obtained between smoothed-particle hydrodynamics simulations and high-resolution stroboscopic experimental data of the droplet deformation dynamics.

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Post-solitons and electron vortices generated by femtosecond intense laser interacting with uniform near-critical-density plasmas

Chinese Physics B ◽

10.1088/1674-1056/ac46c5 ◽

2021 ◽

Author(s):

Dong-Ning Yue ◽

Min Chen ◽

Yao Zhao ◽

Pan-Fei Geng ◽

Xiao-Hui Yuan ◽

...

Keyword(s):

Three Dimensional ◽

Critical Density ◽

Laser Pulses ◽

Intense Laser ◽

Nonlinear Structures ◽

Particle In Cell ◽

Laser Propagation ◽

Laser Driver ◽

Linearly Polarized ◽

Dimensional Simulation

Abstract Generation of nonlinear structures, such as stimulated Raman side scattering waves, post-solitons and electron vortices, during ultra-short intense laser pulse transportation in near-critical-density (NCD) plasmas are studied by using multi-dimensional particle-in-cell (PIC) simulations. In two-dimensional geometries, both P- and S- polarized laser pulses are used to drive these nonlinear structures and to check the polarization effects on them. In the S-polarized case, the scattered waves can be captured by surrounding plasmas leading to the generation of post-solitons, while the main pulse excites convective electric currents leading to the formation of electron vortices through Kelvin-Helmholtz instability (KHI). In the P-polarized case, the scattered waves dissipate their energy by heating surrounding plasmas. Electron vortices are excited due to the hosing instability of the drive laser. These polarization dependent physical processes are reproduced in two different planes perpendicular to the laser propagation direction in three-dimensional simulation with linearly polarized laser driver. The current work provides inspiration for future experiments of laser-NCD plasma interactions.

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Anisotropic refractive-index change in silica glass induced by self-trapped filament of linearly polarized femtosecond laser pulses

Journal of Applied Physics ◽

10.1063/1.1534910 ◽

2003 ◽

Vol 93 (4) ◽

pp. 1889-1892 ◽

Cited By ~ 21

Author(s):

Kazuhiro Yamada ◽

Wataru Watanabe ◽

Junji Nishii ◽

Kazuyoshi Itoh

Keyword(s):

Refractive Index ◽

Femtosecond Laser ◽

Silica Glass ◽

Refractive Index Change ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Index Change ◽

Linearly Polarized

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Nearly Single-Cycle Terahertz Pulse Generation in Aperiodically Poled Lithium Niobate

Photonics ◽

10.3390/photonics6010009 ◽

2019 ◽

Vol 6 (1) ◽

pp. 9 ◽

Cited By ~ 2

Author(s):

Yuri Avetisyan ◽

Masayoshi Tonouchi

Keyword(s):

Lithium Niobate ◽

Field Strength ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Pulse Generation ◽

Closed Form Expression ◽

Single Cycle ◽

Opposite Case ◽

Pulse Form ◽

Domain Length

In the present work, an opportunity of nearly single-cycle THz pulse generation in aperiodically poled lithium niobate (APPLN) crystal is studied. A radiating antenna model is used to simulate the THz generation from chirped APPLN crystal pumped by a sequence of femtosecond laser pulses with chirped delays (m = 1, 2, 3 …) between adjacent pulses. It is shown that by appropriately choosing Δtm, it is possible to obtain temporal overlap of all THz pulses generated from positive (or negative) domains. This results in the formation of a nearly single-cycle THz pulse if the chirp rate of domain length δ in the crystal is sufficiently large. In the opposite case, a few cycle THz pulses are generated with the number of the cycles depending on δ. The closed-form expression for the THz pulse form is obtained. The peak THz electric field strength of 0.3 MV/cm is predicted for APPLN crystal pumped by a sequence of laser pulses with peak intensities of the separate pulse in the sequence of about 20 GW/cm2. By focusing the THz beam and increasing the pump power, the field strength can reach values in the order of few MV/cm.

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Plasmonic layer-selective all-optical switching of magnetization with nanometer resolution

Nature Communications ◽

10.1038/s41467-019-12699-0 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 17

Author(s):

D. O. Ignatyeva ◽

C. S. Davies ◽

D. A. Sylgacheva ◽

A. Tsukamoto ◽

H. Yoshikawa ◽

...

Keyword(s):

Femtosecond Laser ◽

Magnetic Recording ◽

Optical Switching ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

All Optical ◽

Polarization Axis ◽

Linearly Polarized ◽

All Optical Switching ◽

Better Than

Abstract All-optical magnetization reversal with femtosecond laser pulses facilitates the fastest and least dissipative magnetic recording, but writing magnetic bits with spatial resolution better than the wavelength of light has so far been seen as a major challenge. Here, we demonstrate that a single femtosecond laser pulse of wavelength 800 nm can be used to toggle the magnetization exclusively within one of two 10-nm thick magnetic nanolayers, separated by just 80 nm, without affecting the other one. The choice of the addressed layer is enabled by the excitation of a plasmon-polariton at a targeted interface of the nanostructure, and realized merely by rotating the polarization-axis of the linearly-polarized ultrashort optical pulse by 90°. Our results unveil a robust tool that can be deployed to reliably switch magnetization in targeted nanolayers of heterostructures, and paves the way to increasing the storage density of opto-magnetic recording by a factor of at least 2.

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Dynamic alignment of O2investigated by using two linearly polarized femtosecond laser pulses

Journal of Physics B Atomic Molecular and Optical Physics ◽

10.1088/0953-4075/39/5/003 ◽

2006 ◽

Vol 39 (5) ◽

pp. 1035-1043 ◽

Cited By ~ 4

Author(s):

Chengyin Wu ◽

Juan Huang ◽

Nan Xu ◽

Ri Ma ◽

Hong Yang ◽

...

Keyword(s):

Femtosecond Laser ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Linearly Polarized ◽

Dynamic Alignment

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Wakefield generation and electron acceleration by intense super-Gaussian laser pulses propagating in plasma

Laser and Particle Beams ◽

10.1017/s0263034613000682 ◽

2013 ◽

Vol 31 (4) ◽

pp. 583-588 ◽

Cited By ~ 13

Author(s):

Pallavi Jha ◽

Akanksha Saroch ◽

Rohit Kumar Mishra

Keyword(s):

Laser Pulse ◽

Laser Pulses ◽

Gaussian Pulse ◽

Simulation Studies ◽

One Dimensional ◽

Particle In Cell ◽

Peak Energy ◽

Test Electron ◽

Linearly Polarized ◽

Relativistic Regime

AbstractEvolution of longitudinal electrostatic wakefields, due to the propagation of a linearly polarized super-Gaussian laser pulse through homogeneous plasma has been presented via two-dimensional particle-in-cell simulations. The wakes generated are compared with those generated by a Gaussian laser pulse in the relativistic regime. Further, one-dimensional numerical model has been used to validate the generated wakefields via simulation studies. Separatrix curves are plotted to study the trapping and energy gain of an externally injected test electron, due to the generated electrostatic wakefields. An enhancement in the peak energy of an externally injected electron accelerated by wakes generated by super-Gaussian pulse as compared to Gaussian pulse case has been observed.

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Super-hard coatings deposited under conditions of the dynamic shock wave and measurement features of control parameters during production

Journal of the Mechanical Behavior of Materials ◽

10.1515/jmbm-2020-0017 ◽

2020 ◽

Vol 29 (1) ◽

pp. 169-176

Author(s):

Oleg Kuzmin

Keyword(s):

Laser Beam ◽

High Speed ◽

Laser Annealing ◽

Chemical Properties ◽

Laser Pulses ◽

Laser Wavelength ◽

Femtosecond Laser Pulses ◽

Hard Coatings ◽

Linearly Polarized ◽

Physical And Chemical

AbstractSuper-hard coatings are of increasing scientific interest as they allow synthesizing materials with unique physical and chemical properties for further application in the industry at high-speed processing or tooling. This study is aimed to investigate tetrahedral amorphous carbon (ta-C) films, as well as the dependence of the pulsation parameters on the irradiation parameters and the potential of such pulsations to be further applied in practice. The article shows that ta-C films are completely amorphous and have up to 85% of sp3 bonds. Deposited films are characterized by high compression stresses ranging within 8-10 GPa. The possibilities of reducing these stresses by thermal and pulsed laser annealing have been examined. The formation of ripples in super-hard ta-C films were studied by applying femtosecond laser pulses with a wavelength of 775 nm, an average wavelength of 387 nm, and the pulse duration of 150 fs. Obtained results demonstrated that the orientation of the pulsations on smooth surfaces is perpendicular to the vector of the electric field of the linearly polarized laser beam. Besides, the period of pulsation reduces with decreasing the laser wavelength and/or increasing the angle of laser beam incidence on the substrate.

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