An analytical and numerical study of the stability of sheet electron beams in periodically cusped magnetic fields (PCM) is made. The beam has been considered as having edges with a prescribed density variation. In estimating the electrostatic fields, we have considered the density variation of both the edges along the width and thickness of the sheet beam. The conditions for beam focusing and beam matching are discussed.

The penetration of the long-focused monochromatic radiation pulse into plasma whose density is much higher than critical has been modeled by simultaneous solution wave equation for the field and the gasdynamics equations for plasma in 2D axial symmetric case. The method and computation results are presented showing the effect of quasiwaveguide propagation of a pulse into plasma to a depth sufficiently exceeding the wavelength.

Shock waves generated on eight meteorite and two Al targets by 5.4–5.6 J, 20-ns pulsed Nd:glass laser at 1054 nm generated peak pressures from 0.7 to 11 Gpa. The shock-induced particle velocities in the targets versus time was measured interferometrically. The target momentum coupling and mechanical momentum/energy coupling was highest for the Al. Among the meteorites the coupling was greatest for the Fe-Ni, which maintained physical integrity, and lowest for the stony meteorites, all of which disintegrated. Using particle velocity measurements, shock results are interpreted in terms of target fragmentation, inhomogeneity, and microstructural characteristics which are the dominant target parameters effecting energy and momentum coupling. Normalized values for the shocked material velocity and peak pressure in the targets compare favorably to similar experimental work on Al targets. Applications to modeling high-velocity meteoroid impact with planetary atmospheres, space debris remediation, and near-Earth object material interactions are discussed.

A relativistically intense short laser pulse can produce a large flux of X rays through the interaction with electrons that are driven by its intense electromagnetic fields. Apart from X rays from the high-Z matter irradiation by an intense laser, two main processes, Larmor and Bremsstrahlung radiation, are among the most significant mechanisms for X-ray emission from short-pulse laser irradiation on low-Z matter in the regime of relativistic intensities. We evaluate the power, energy spectrum, brilliance, polarization, and time structure of these X rays. We suggest a few methods that significantly enhance the power of Larmor X rays. Because of the peakedness in the energy spectrum of Larmor X rays, Larmor X rays have important applications.

We report the instrument description and the results of the laboratory calibration and tests of a mid-infrared tunable diode spectrometer for in situ trace gas concentration measurements in the stratosphere operating on a stratospheric aircraft. The spectrometer is dedicated to the measurement of the HNO3 amount in the stratospheric aerosols by means of gas-phase absorption spectroscopy on molecular roto-vibrational lines in the mid-infrared, using a tunable diode laser and a multipass absorption cell. The instrument was specifically designed for operation aboard of the stratospheric aircraft M55 Geophysica, in the frame of the Airborne Platform for Earth observation (APE) project. The instrument is part of a measurement package for the measurement of the chemical content of Polar Stratospheric Clouds (PSCs) and other atmospheric aerosols. This system can be also used as a stand-alone detector of molecular trace gases. Design criteria include an efficient optical layout, with a very low sensitivity to the vibration and thermal stresses and a very small footprint, and a detection scheme based on the sweep integration technique for fast data acquisition and high signal-to-noise (S/N) ratio. We report a new set of testing measurements on ammonia as the calibration gas with one order of magnitude improvement with respect to what we previously reported.

Multistage, e-beam-pumped, 100 J-class KrF laser installation “GARPUN” is described with the emphases to high-power laser beam control and target irradiation experiments. The ablation pressures in the megabar range were measured and hydrodynamic flow was investigated both experimentally and by numerical simulations for laser intensities up to 5×1012 W/cm2, pulse duration of 100 ns, and focal spot diameter 150 μm. Graphite-diamond phase transformation under laser loading was observed by dynamic and Raman scattering methods. Some approaches to the fast ignition inertial confinement fusion, using the simultaneous amplification of long and short laser pulses in KrF drivers, are considered.

Phase conjugation process at intracavity degenerate four wave mixing of a long pulse CO2 laser radiation in its active medium has been studied experimentally. Dependencies of energetic and temporal characteristics of the phase conjugation signal upon specific energy stored into electric discharge, Q-factor of laser resonator, laser mixture composition and pressure, interaction angle, optical delay between probe and co-propagating waves, intensity ratio for these waves J3/J1, a degree of linear polarization, and laser spectrum are analyzed. Reflectivity of the phase conjugation signal is shown to increase with specific input energy rise and a decrease of the ratio J3/J1, being up to 7.5%. An increase of nitrogen content and a decrease of helium content in the laser mixture results in reflectivity rise and peculiar laser pulse profile with two maximums being due to amplitude and phase nonlinearities of the active medium. Specific input energy rise and an increase of Q-factor leads to a decrease of response time for the phase conjugation signal. Nonlinear properties of degenerate four wave mixing on amplitude gain and phase thermal diffraction gratings in the active medium of a long pulse CO2 laser are analyzed theoretically. An interconnection of nonlinear parameters of the amplifying media with the temporal behavior of phase conjugation reflectivity is determined. A comparison of the theoretical calculations and the experimental data has been done.

In this paper, we present and discuss an extension and an improvement of the Figure of Merit (FoM) that we introduced in a previous paper. The FoM describes the effectiveness of the frequency doubling materials for ultrashort light pulse modulators via second-order cascaded effects. In the present work, as an input pulse we use a temporal Gaussian pulse so that our perturbative method allows an analytical expression even for the output pulse field after the second pass inside the crystal. For the first time together with the completely analytical expression for the second pass, we report also the exact numerical coefficients for the peak phase modulation. With the FoM it is possible to choose the more appropriate nonlinear material and the use of the cascaded interaction process. Finally, we present for the first time the FoM dependence from the wavelength in the interval 0.5–1 μm, and to a table already shown we added more nonlinear materials.

This work proposes an analytical perturbative method describing the effects on the propagation of finite aperture beams due to the self-phase and self-amplitude modulation which result from cascaded second order interaction of ultrashort light pulses. The method merges the semi-analytical solution with a perturbative beam propagation technique, namely the Gaussian Beam Decomposition, which describes the effects of the non linear modulation on the free beam propagation. In particular we have studied the problem of the time- and intensity-dependent transmission of the pulse through slits or apertures placed along the path of the beam simulating a geometry suitable for passive laser mode-locking. Although an efficient pulse shortening action can be obtained in stationary conditions, in non stationary conditions the occurrence of an unavoidable amplitude modulation perturbs the beam propagation and reduces the temporal selectivity of the modulator.

We demonstrate that short laser pulse self-guiding over distances of many Rayleigh lengths can be achieved in the absence of any focusing nonlinearity as a result of trapping of a leaking wave in a plasma channel produced by field-induced ionization in the saturation regime. A detailed computational study of the new self-guiding effect in both cases of comparatively long laser pulses, when the traditional approximation of the slowly varying complex amplitude is valid, and of high intense ultrashort laser pulses comprising only few field cycles have been performed.

The field of diffractive optics is at the same time old and young. Diffraction gratings have been known for two centuries and used extensively in spectroscopy, for example. Also the theoretical understanding of the basic properties of grating diffraction has been well developed since that time. Until the 1960s, the technological foundation of grating manufacture used to be precision mechanics. It was then, when with the advent of the laser, things gradually started to change. On the one hand, laser interferometry became an additional tool to fabricate grating structures with very small periods. On the other hand, many new applications for optics started to develop based on the use of different types of laser sources. Some examples that may be mentioned are—besides modern spectroscopic techniques—areas like material processing, optical communications and information processing, optical data storage, etc. Consequently, the term “diffractive optics” has obtained a different flavor during the past 20–30 years. New types of diffractive elements were being developed with new technologies. This started in the mid-1960s with the invention of computer-generated holography which allowed to create “arbitrary” wavefronts (this means, within practical limits) by diffracting a light wave at an irregular binary structure. The computation and fabrication of computer-generated holograms was made possible by then newly available digital computers and plotting equipment. Since the early 1970s, people started to make diffractive elements using microfabrication techniques (lithography, etching, etc.) adapted from the processing of electronic circuits. These ideas were initially demonstrated in industrial research laboratories like Philips and Thomson-CSF.