Interaction Of Intense Laser Radiation Research Articles

Efficient Generation of Attopulses at the Interaction of Intense Laser Radiation with Ultrathin Targets

Efficient Generation of Attopulses at the Interaction of Intense Laser Radiation with Ultrathin Targets

Efficient generation of attopulses at the interaction of intense laser radiation with ultrathin targets

Parameters (thickness, electron density) of the laser target in the form of ultrathin foil are determined that provide maximum (~ 10%) conversion ratio of short relativistically intense laser pulses into a train of several coherent attopulses. Attopulse amplitude, duration are determined, conversion ratio of laser energy into the energy of attopulses is determined and the possibility of its increase using several successively located targets is shown. Keywords: ultraintense laser pulse, attopulse, laser plasma, laser target.

Phase characteristics of high-order harmonics in the cut-off region

The behavior of the phases of high-order harmonics generated upon interaction of intense laser radiation with matter is investigated. Some specific features typical of the harmonic phases in the high-frequency part of plateau (cut-off harmonic phases) are found. First, the phase difference between neighboring harmonics is a constant value. The width of the spectral range in which this regularity occurs determines the minimum duration of the attosecond pulse obtained from these harmonics by the so-called amplitude gating technique. Second, it is shown that the phase of each harmonic in the cut-off region depends linearly on the laser intensity. The proportionality coefficient is the same for all harmonics in this region and proportional to the cube of laser wavelength. Thus, this dependence is especially important for generating high-order harmonics by lasers with a wavelength of few micrometers.

Editorial for Special Issue on Multiphoton Processes

With the rapid development of ultrafast intense laser technologies, the interaction of intense laser radiation with matter has been a frontier for few decades. The International Conference on Multiphoton Processes (ICOMP), initiated in 1977, covers the latest advances in the field every three years. The special issue is based on the spirit of the 13th International Conference on Multi-Photon Processes, ICOMP13, which was held in Shanghai, organized by Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, on Dec. 7-10, 2014.

Optical near-fields & nearfield optics

Optical near-fields & nearfield optics

Theory of the interaction of intense laser radiation with magnetoactive plasma

Analytical expressions for the density of magnetoactive plasma perturbed by circularly polarized relativistically strong laser radiation are obtained.

Interaction of intense laser radiation with weak electromagnetic waves in an evacuated section of a ring laser

A laboratory experiment for the study of nonlinear interaction of electromagnetic waves in vacuum is proposed. The basic idea of the experiment is as follows. If one separates a certain region of the circuit in a ring laser from the remaining part with gas-impenetrable partitions, evacuates it, and forms external electromagnetic fields there, the oscillation frequencies and the polarization states of the electromagnetic waves traveling in this ring laser in counter directions are different. A calculation is made for the oscillation frequencies of electromagnetic waves traveling in a ring laser in opposite directions in the case when they interact in an evacuated section of the ring laser circuit with intense laser radiation. It is shown that the effect can be observed in experiments using presently available pulsed lasers of ultrahigh power.

Influence of corundum structure on the characteristics of multiply charged ions in a laser-produced plasma

An investigation was made of the interaction of intense laser radiation (λ = 1.06 μm) with previously irradiated corundum. The studies were performed in the collecting mode by employing time-of-flight mass spectrometry. Electron and ion currents were considered simultaneously with charge-state and energy characteristics of multiply charged ions of the plasmas produced at the source and previously irradiated targets. The combined consideration allows the conclusion that the prior neutron irradiation of a sample by a fluence of 1015 — 1019 neutron cm-2 makes for production of a higher-temperature plasma.

Time-Resolved, Multi-frame X-Ray Imaging of Laser-Produced Plasmas

A novel x-ray imaging system based on a microchannel-plate combined with a multi-pinhole camera has been employed to study x-ray emission from laser-produced plasmas in the 0.5–3 keV photon energy range. In particular, the interaction of intense laser radiation with such plasmas, under conditions relevant to inertial confinement fusion, was monitored by recording a sequence of consecutive x-ray images with a temporal resolution of 140 ps and a spatial resolution of 10 μm. These images provide valuable information on the main physical mechanisms involved in the interaction process, including collisional absorption of the incident laser energy and electron thermal conduction.

Time-Resolved, Multi-frame X-Ray Imaging of Laser-Produced Plasmas

A novel x-ray imaging system based on a microchannel-plate combined with a multi-pinhole camera has been employed to study x-ray emission from laser-produced plasmas in the 0.5-3 keV photon energy range. In particular, the interaction of intense laser radiation with such plasmas, under conditions relevant to inertial confinement fusion, was monitored by recording a sequence of consecutive x-ray images with a temporal resolution of 140 ps and a spatial resolution of 10 μm. These images provide valuable information on the main physical mechanisms involved in the interaction process, including collisional absorption of the incident laser energy and electron thermal conduction.

Theory of laser-induced free-electron heating and impact ionization in wide-band-gap solids.

A microscopic theory for the interaction of intense laser radiation at visible and near-infrared wavelengths with free electrons in a wide-band-gap solid is presented. We calculate the free-electron mediated energy transfer from the laser field to the solid and the electron-multiplication rate due to band-to-band ionization as a function of laser intensity at wavelengths in the range 250 nm10 \ensuremath{\mu}m, using ${\mathrm{SiO}}_{2}$ as an example. The formalism is based on a Monte Carlo integration of the Boltzmann transport equation. The electron interaction with the lattice is described in terms of polar and acoustic-phonon scattering. Band-to-band impact ionization is included using an empirical, Keldysh-type impact ionization rate. The interaction of the laser radiation with the free electrons is treated both within the standard classical approximation and quantum mechanically using second-order perturbation theory. We find that the classical approach to the electron-laser field interaction is valid for \ensuremath{\lambda}>2 \ensuremath{\mu}m, while reliable results for short wavelengths, \ensuremath{\lambda}1 \ensuremath{\mu}m, can only be obtained by using the quantum approach. Second-order perturbation theory is found to fail at long wavelengths, \ensuremath{\lambda}>1 \ensuremath{\mu}m. Both methods are inaccurate for \ensuremath{\lambda}\ensuremath{\simeq}1 \ensuremath{\mu}m, yielding only upper and lower bounds for calculated quantities. For \ensuremath{\lambda}>2 \ensuremath{\mu}m the calculated quantities are found to be close to the values obtained in the dc limit, using a dc field equal to the rms value of the ac field. For \ensuremath{\lambda}1 \ensuremath{\mu}m the electron-multiplication rates decrease dramatically as wavelengths become shorter indicating that multiphoton absorption becomes the dominant mechanism for free-electron generation at visible wavelengths. At all wavelengths the theory predicts efficient free-electron mediated energy transfer from the laser field to the lattice. It is therefore possible to observe significant lattice heating caused by free electrons generated via multiphoton absorption in the prebreakdown regime. These findings are shown to be consistent with recent laser experiments [S. Jones, P. Braunlich, R. Casper, X. Shen, and P. Kelly, Opt. Eng. 28, 1039 (1989)].

Frequency dependent electric polarisation due to optical rectification: Effect on far infra red bandshapes.

The symmetry principles governing the non-linear interaction of intense laser radiation with molecular ensembles show that dynamical interaction phenomena exist in the ensemble even though the induced frequency dependent polarisation be purely imaginary, and unobservable in the static limit. An example is computer simulated in the S enantiomer of bromochlorofluoromethane, showing clear effects on the orientational and rotational velocity correlation functions and by Fourier transform, the dielectric and far infra red spectra. Conditions are suggested for its experimental observation and order of magnitudies calculated for the appropriate mediating tensors.

Frequency-dependent electric polarization due to optical rectification: Computer simulation and semiclassical theory.

The symmetry principles governing the nonlinear interaction of intense laser radiation with molecular ensembles show that dynamical interaction phenomena exist in the ensemble even though the induced frequency-dependent polarization could be purely imaginary and unobservable in the static limit. An example is computer simulated in the S enantiomer of bromochlorofluoromethane, showing clear effects on the orientational and rotational velocity correlation functions and by Fourier transforming these functions, the dielectric and far-infrared spectra. Conditions are suggested for its experimental observation and orders of magnitude calculated for the appropriate mediating tensors.

Optical polarization of diatomic molecules

Originally, he says, man was round, his back and sides forming a circle. Hermann Weyl, Symmetry (on Plato's Dialogue Symposium). The evolution of polarization (alignment and orientation) of angular momenta of diatomic molecules both in the ground and excited states upon absorption of light is examined. The effect of external factors—magnetic field and collisions—on this polarization is investigated. Interference effects (level crossing, quantum beats, beat resonance) and the possibilities of employing them to determine magnetic and relaxation characteristics of individual vibration-rotation levels are analyzed. A classical description of phenomena is given in terms of distribution of angular momenta, including the use of isometric projections of the distribution being formed. Equations are given that describe the interaction of intense laser radiation with an ensemble of molecules in the gas phase. Other mechanisms are presented for the evolution of angular momenta for the ground electron state of diatomic molecules.

Interactions of intense laser radiation with plasma

The dominant physical processes involved in the interaction of intense laser radiation with plasma are discussed with emphasis on their dependence on the wavelength of the laser radiation. Hydrodynamic pressure resulting from these interactions, acceleration of spherical shell targets, and fluid instability associated with the acceleration are discussed with reference to compression of plasma in laser driven implosions. Experimental data are presented to illustrate the various phenomena.

Thermonuclear fusion by high-power lasers

It may be possible to ignite small deuterium-tritium pellets by the focused radiation of powerful lasers. Crucial for the success of this alternate approach to fusion energy is the understanding of the interaction of intense laser radiation with plasma and the construction of suitable lasers with powers in the 100 TW regime. The author describes the present status of this field with particular emphasis on the interaction problem and its implication on the wavelength of the laser, existing high-power laser installations and trends in future laser development.

Plasmas and Laser Light

T P Hughes London: A Hilger 1915 pp xxi + 518 price £35 There is now considerable interest in the interaction of intense laser radiation with matter, primarily as a result of work on laser fusion, and this text is the first to appear on the subject. Most of the book is concerned with a review of work on laser induced ionization and gas breakdown and on the interaction of laser radiation with solid targets.

Time-dependent approach to the interaction of intense laser radiation with matter

Time-dependent approach to the interaction of intense laser radiation with matter