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Problems associated with the radiography of objects made of steel having thickness of 100 mm and more are outlined. The classical method of gathering information provides for mounting semiconductor photo detectors directly on scintillators. As a result, gamma radiation scattered in a scintillator enters photo detector increasing the image noise and providing a negative effect on processing electronics. A method to design a recording system using a wavelength-shifting fiber having no disadvantages of the classical technique is proposed. This method makes it possible to decrease the image noise, to remove electronics from direct effect of gamma radiation and to increase the registration efficiency. Various approaches of implementing the method proposed to detect signals are explored experimentally with selecting the optimal techniques. This research enabled developing a design base to engineer recording element. The results on measuring parameters of the registering element are presented.

The effect of parameters of a polarization nephelometer on its accuracy characteristic is analyzed. Errors in approximation of the actual scattering volume and actual optical beam by the elementary scattering volume and elementary beam are considered. A five-wave monochromatic source of radiation with the high spectral intensity of 0.15÷0.6 W is described. The design of polarization units is demonstrated.

The compression and burning of a fusion target ignited by a focused shock wave produced at the action of a time-profiled second harmonic laser pulse of a Nd laser have been calculated and theoretically studied. The main energy features of the shock ignition scheme have been considered. The use of the second harmonic radiation corresponds to a higher energy and a longer laser pulse necessary for ignition by this method compared to the use of the third harmonic radiation. Nevertheless, the method of ignition by the focused shock wave with the second harmonic radiation makes it possible to reach the fusion target gain that is two or three times higher than that at the traditional spark ignition with the laser pulse energy higher than in the former case by a factor of 1.5. The numerical calculations have been performed with one-dimensional hydrodynamic codes.

Possibilities of increasing the electron beam energy concentration in the electron-optical system of a welding gun characterized by a traditional scheme in which a focusing lens and a deflecting system are installed sequentially along the beam and a new scheme based on a focusing–deflecting system with combined fields are considered. A technique based on solving the paraxial equations of trajectories and calculating aberration integrals is described, which allows one to determine the total diameter of the electron beam. Based on the described methodology, a model of a new focusing–deflecting system with combined fields has been developed. It is shown that the new scheme of the electron-optical system allows one to increase the energy concentration in the region of the interaction of the beam with the material in comparison with the traditional one.

Nonlinear metasurfaces have become prominent tools for controlling and engineering light at the nanoscale. Usually, the polarization of the total generated third harmonic is studied. However, diffraction orders may present different polarizations. Here, we design an high quality factor silicon metasurface for third harmonic generation and perform back focal plane imaging of the diffraction orders, which present a rich variety of polarization states. Our results demonstrate the possibility of tailoring the polarization of the generated nonlinear diffraction orders paving the way to a higher degree of wavefront control.

Small form-factor, narrow band, and highly directive antennas are of critical importance in a variety of applications spanning wireless communications, remote sensing, Raman spectroscopy, and single photon emission enhancement. Surprisingly, we show that the classical directivity limit can be appreciably surpassed for electrically small multilayer spherical antennas excited by a point electric dipole even if limiting ourselves to purely dielectric materials. Experimentally feasible designs of superdirective antennas are established by using a stochastic optimization algorithm combined with a rigorous analytic solution.

Time-dependent nonlinear media, such as rapidly generated plasmas produced via laser ionization of gases, can increase the energy of individual laser photons and generate tunable high-order harmonic pulses. This phenomenon, known as photon acceleration, has traditionally required extreme-intensity laser pulses and macroscopic propagation lengths. Here, we report on a novel nonlinear material—an ultrathin semiconductor metasurface—that exhibits efficient photon acceleration at low intensities. We observe a signature nonlinear manifestation of photon acceleration: third-harmonic generation of near-infrared photons with tunable frequencies reaching up to ≈3.1ω. A simple time-dependent coupled-mode theory, found to be in good agreement with experimental results, is utilized to predict a new path towards nonlinear radiation sources that combine resonant upconversion with broadband operation., Photon acceleration, which can be used to generate tunable high harmonic radiation, typically requires high-intensity lasers and long propagation distances. Here, Shcherbakov et al. show efficient photon acceleration at low power input power from a semiconductor metasurface, less than a micron thin.

Electromagnetic scattering on subwavelength structures keeps attracting attention owing to abroad range of possible applications, where this phenomenon is in use. Fundamental limits of scattering cross-section, being well understood in spherical geometries, are overlooked in cases of low-symmetry resonators. Here, we revise the notion of superscattering and link this property with symmetry groups of the scattering potential. We demonstrate pathways to spectrally overlap several eigenmodes of a resonator in a way they interfere constructively and enhance the scattering cross-section. As a particular example, we demonstrate spectral overlapping of several electric and magnetic modes in a subwavelength entirely homogeneous ceramic resonator. The optimized structures show the excess of a dipolar scattering cross-section limit for a sphere up to a factor of four. The revealed rules, which link symmetry groups with fundamental scattering limits, allow performing and assessing designs of subwavelength supperscatterers, which can find a use in label-free imaging, compact antennas, long-range radio frequency identification, and many other fields., 9 pages, 5 figures

The possibility of controlling the spectrum of the generated third harmonic for high quality-factor resonant metasurfaces is examined. The ultrafast dynamics for both fundamental wavelength and third harmonic generation is observed in all-dielectric metasurfaces with pump-probe technique.

This work is devoted to the investigation of the enhancement of Raman signals of nonadsorbed gases in the vicinity of corrugated metallic surfaces supporting propagating surface plasmon-polaritons (PSPPs). Simulation of the PSPP excitation efficiency on holographic gratings coated with silver films of various thicknesses at different groove heights was carried out. Verification showed good agreement between theory and experiment. Also, it was found that an increase of the PSPP excitation efficiency may not lead to an increase in the enhancement factor of Raman signals of gases located near the surface-enhanced Raman scattering active surface. For a holographic grating with a period of 667 nm, a groove height of 70 nm, and a silver film thickness of 30 nm coated with a protective A l 2 O 3 layer, the enhancement factor of Raman signals of nonadsorbed nitrogen molecules was ∼ 4 ⋅ 10 3 .

We present experimental observations of frequency conversion and negative optical extinction in time-variant metasurfaces and their applications to surpassing the time-bandwidth limit in photonics.

One of the most desirable functions of a diffraction grating is its ability to scatter incident light into a specific diffraction order with near-perfect efficiency. While such asymmetry can be achieved in a variety of ways, for example, by using a sawtooth (blazed) geometry, a recently emerged approach is to use planar metagratings comprised of designer multiresonant periodic units (metamolecules). Here we demonstrate that a bianisotropic metamolecule supporting four resonances of the appropriate symmetry can be used as a building block for achieving perfect diffraction. Coupled-mode analysis shows that these resonant modes provide a small number of orthogonal electromagnetic radiation patterns that are needed to suppress transmission/reflection into all but one diffraction order. Bianisotropy caused by breaking the metamolecule’s mirror symmetry enables a normally incident wave to excite two otherwise “dark” resonant modes through near-field couplings. We design and experimentally realize such bianisotr...

Resonant semiconductor metasurfaces are an emerging versatile platform for nonlinear photonics. In this work, we investigate second-harmonic generation from metasurfaces consisting of two-dimensional square arrays of gallium arsenide nanocylinders as a function of the polarization of the fundamental wave. To this end, we perform nonlinear second harmonic microscopy, where the pump wavelength is tuned to the resonances of the metasurfaces. Furthermore, imaging the generated nonlinear signal in Fourier space allows us to analyze the spatial properties of the generated second harmonic. Our experiments reveal that the second harmonic is predominantly emitted into the first diffraction orders of the periodic arrangements, and that its intensity varies with the polarization angle of the fundamental wave. While this can be expected from the structure of the GaAs nonlinear tensor, the characteristics of this variation itself are found to depend on the pump wavelength. Interestingly, we show that the metasurface c...

Subwavelength optical resonators and scatterers are dramatically expanding the toolset of the optical sciences and photonics engineering. By offering the opportunity to control and shape light waves in nanoscale volumes, recent developments using high-refractive-index dielectric scatterers gave rise to efficient flat-optical components such as lenses, polarizers, phase plates, color routers, and nonlinear elements with a subwavelength thickness. In this work, we take a deeper look into the unique interaction of light with rod-shaped amorphous silicon scatterers by tapping into their resonant modes with a localized subwavelength light source-an aperture scanning near-field probe. Our experimental configuration essentially constitutes a dielectric antenna that is locally driven by the aperture probe. We show how leaky transverse electric and magnetic modes can selectively be excited and form specific near-field distribution depending on wavelength and antenna dimensions. The probe's transmittance is furthermore enhanced upon coupling to the Fabry-Perot cavity modes, revealing all-dielectric nanorods as efficient transmitter antennas for the radiation of subwavelength emitters, in addition to constituting an elementary building block for all-dielectric metasurfaces and flat optics.

The use of the thermal imaging method for active nondestructive evaluation of subsurface defects of articles is examined. The scale factors for converting the values of defect size from pixels to length units are estimated. The effect of size and depth of a defect on the distribution of heat along the surface is analyzed.

The optical properties of color centers in nanodiamonds are widely used in various branches of photonics and interdisciplinary studies. Here, we report on an experimental study of the fundamental eigenmodes of subwavelength diamond nanoparticles. The eigenmodes reveal themselves as scattering resonances, which were measured by single-particle dark-field spectroscopy and calculated both numerically and analytically. The resonances experience a red-shift with increasing particle size, and in the case of an anisotropic particle, they change depending on the polarization of the input light. As an example of an application, the Purcell enhancement of the dipole emission from such nanodiamonds is numerically demonstrated. This study demonstrates a simple way to improve the efficiency of diamond-based sensors and single-photon sources by choosing nanoparticles of optimal size and shape.

The D2О absorption spectrum was recorded between 10000 and 11400 cm–1 by a Fourier transform spectrometer with a spectral resolution of 0.05 cm–1. A multipass White-type cell with an optical path length of 24 m was used for the spectrum measurements. A light-emitting diode served as a radiation source, because it provides a higher brightness as compared to other emitters. A signal-to-noise ratio of 104 was gained for the strongest lines. During the D2О spectrum treatment, the experimental line list of about 100 lines of the ν1 + 3ν3 band was created. Spectroscopic parameters (line positions, intensities, and half widths) were calculated from fitting the experimental data to the Voigt line profiles by the least squares method. The analysis of the spectrum allowed us to derive new energy levels belonging to the vibrational state (103) of D2 16О.

Six absorption bands of Tm3+:Sc2SiO5 crystal have been investigated by decomposing each absorption band into a series of Lorentzian peaks. Polarized light of two polarizations was transmitted in three perpendicular directions through a crystal shaped as a parallelepiped with polished faces. The results are presented in the form of tables containing the parameters of the found Lorentzian peaks: central wavelength, width, and height.

The article presents a curvilinear coordinate Fourier space integral method for linear optical rigorous grating diffraction simulation in 3D (crossed grating diffraction). The presented formulation extends our previous work on a related method for 1D periodic grating diffraction. Following this previous work we exploit a concept of the generalized metric sources to efficiently solve the Maxwell׳s equations. The article provides a general description of the method together with a detailed formulation and analysis of sinusoidal corrugation crossed grating diffraction.

The urgency of solving the problem of determining the deposited layer’s height for controlling the process of additive forming products from metallic materials in a vacuum is substantiated. A scheme of electron-beam additive manufacturing process with wire feed is shown. A method for controlling the distance between deposited bead and electron gun by the signal taken from a collector of backscattered electrons is proposed. The analysis of the signals recorded during the process of deposited metal bead scanning has been carried out, and technical feasibility of this method has been substantiated. The technical solutions to introduce a method for continuous monitoring and control of additive forming process are proposed. A series of computational experiments at using the Monte Carlo method were carried out. They confirmed the relevance of the proposed method for controlling the distance between the electron gun and deposited bead. The calculation of beam energy fraction absorbed by the collector made it possible to substantiate the need for using a signal preamplifier. Based on the analysis of the results of experimental studies conducted on the ELA-15I power complex, the relevance of the proposed method for measuring the working segment and the possibility of using it as part of a process control system was confirmed.

The article focuses on depth-dependent visible band transmission effects in a symmetrical “insulator-metal-insulator” diffraction system based on a variable depth grating. These effects were studied both experimentally and theoretically in TM and TE polarizations. In particular, the existence of an optimized grating depth for plasmon-mediated resonant transmission was confirmed experimentally, and differences in TE and TM transmission behavior are discussed. We utilize a simple and flexible fabrication approach for rapid synthesis of apodized structures with adiabatically varying depth based on a beat pattern of two interferential lithography exposures. The present study can be useful in the fields of transmission-based optical security elements and biosensors.

International audience; The Maggi-Rubinowicz method (MRM) is a useful tool to compute diffraction patterns from opaque planar objects. We adapted the MRM to planar rectangles. In the first part of this study, differences between diffraction patterns, both the intensity and the phase distributions, from a tilted rectangle and from the square having the same orthogonal projection on the observation plane, have been analyzed. In the second part, we compared results obtained with the MRM to those obtained with angular spectrum theory (AST) coupled to fast Fourier transform (FFT). The main novelty of this work is the fact that MRM is particularly well suited for evaluating anti-aliasing procedures applied to AST-FFT calculations.

Optical array probes (OAPs) are classical instrumental means to derive shape, size, and number concentration of cloud and precipitation particles from 2-D images. However, recorded 2-D images are subject to distortion based on the diffraction of light when particles are imaged out of the object plane of the optical device. This phenomenon highly affects retrievals of microphysical properties of cloud particles. Previous studies of this effect mainly focused on spherical droplets. In this study we propose a theoretical method to compute diffraction patterns of all kinds of cloud particle shapes in order to simulate the response recorded by an OAP. To check the validity of this method, a series of experimental measurements have been performed with a 2D-S probe mounted on a test bench. Measurements are performed using spinning glass discs with imprinted non-circular opaque particle shapes.

High-efficient direct numerical methods are currently in demand for optimization procedures in the fields of both conventional diffractive and metasurface optics. With a view of extending the scope of application of the previously proposed Generalized Source Method in the curvilinear coordinates, which has theoretical $O\left(N\log N\right)$ asymptotic numerical complexity, a new method formulation is developed for gratings with sharp edges. It is shown that corrugation corners can be treated as effective medium interfaces within the rationale of the method. Moreover, the given formulation is demonstrated to allow for application of the same derivation as one used in classical electrodynamics to derive the interface conditions. This yields continuous combinations of the fields and metric tensor components, which can be directly Fourier factorized. Together with an efficient algorithm the new formulation is demonstrated to substantially increase the computation accuracy for given computer resources., Comment: 12 pages, 4 fugures

Acousto-optic Q-switched lasing has been obtained for the first time in a Tm:Ho:YbAGcrystal. The laser output power is analyzed as a function of the laser pulse repetition rate. It is found that at rates above 30 kHz the laser slope efficiency reaches maximum values (~20 to 30%), comparable with the efficiency in the cw mode. The shortest laser pulse width is about 40 ns, and the average output power reaches about 80mW.

We consider an X-ray optical system which permits obtaining laser plume images at a wavelength of 13.5 nm with a resolution of up to 70 nm. The X-ray optical system comprises an X-ray Schwarzschild objective made up of two aspherical multilayer mirrors, a scintillator (YAG : Ce ceramics), which converts X-rays to the visible radiation, and a visible-optical system, which images the scintillator surface onto a CCD camera. The spatial resolution of the system is limited by the resolution of the optical system (0.7 μm) and the magnification (10×) of the X-ray objective and is as high as 70 nm. The effect of Schwarzschild objective mirror shapes on the spatial resolution is analysed. The profile of concave mirror aspherisation is considered, which provides the attainment of the diffraction-limited quality of the objective. Data are given for the quantum efficiency of the system at a wavelength of 13.5 nm. We describe the experimental test bench intended for studying the developed X-ray optical system and outline the first experimental data which illustrate its efficiency. Owing to the natural division into the 'X-ray' and 'visible' parts, the optical system under discussion permits an easy change of the magnification and the field of view without realigning the X-ray optical elements. The wavelength may be varied in a range between 3 and 40 nm by changing the multilayer mirrors.

The vibrational—rotational spectrum of the HD16O molecule is studied within the range of 11200−12400 cm−1. The spectrum is recorded by an IFS-125M Fourier spectrometer with a resolution of 0.05 cm−1. The measurements are performed using a multipass White cell. A light-emitting diode is used as a radiation source. The signal-to-noise ratio was about 104. The centers, intensities, and half-widths of the spectral lines are determined by fitting to the experimental data by the least-squares method. A linelist containing more than 1500 lines is created. The results obtained are compared with the experimental data of other authors.

The H2 16O vapor absorption line broadening by nitrogen pressure is investigated in the range of 12411–12421 cm −1 using a laser optoacoustic spectrometer with a Ti: sapphire laser having a lasing line width of 50 kHz. The broadening coefficients of 7 H2O lines determined by transitions to levels with the vibrational quantum numbers v = 4–8 are measured with an absorption sensitivity threshold of 10 −8 cm −1 . Experimental line half-widths are compared with their values calculated by the semi-empirical method.

Plasmon polaritons in thin gold nanoslit gratings with a fixed period and a variable filling factor are studied using microspectroscopy measurements and finite-difference time-domain simulations. The regimes of surface plasmon polaritons, localized plasmons, and the mixed mode are identified.

An experimental technique for the acquisition of current-density distributions of continuously operating electron beams with an electron energy of 60 keV is proposed. The measurement results for different cross-sectional areas of the beam with a power of 2.1 kW and a current density around 1 × 105 A/m2 are given.

The method of luminescence with a time resolution of 2 ns has been applied to studying the dynamics of the surface destruction of uniaxially compressed granite by a shock wave caused by electric discharge in air near its surface. The shock impact causes emission of jets of positively charged ions from the most strongly distorted regions on the sample surface. It has been discovered that, when the compressing stress reaches ~0.92–0.95 times the sample’s breaking stress, two maxima can be observed on the time dependence of the jet intensity. The first maximum corresponds to the shock wave reaching the sample surface and the second maximum corresponds to the crack destroying the sample.

International audience; The work considers the effect of extraordinary optical transmission (EOT) in polycrystalline arrays of nanopores fabricated via nanosphere photolithography (NPL). The use of samples with different qualities of polycrystalline structure allows us to reveal the role of disorder for EOT. We propose a phenomenological model which takes the disorder into account in numerical simulations and validate it using experimental data. Due to the NPL flexibility for the structure geometry control, we demonstrate the possiblity to partially compensate the disorder influence on EOT by the nanopore depth adjustments. The proposed experimental and theoretical results are promising to reveal the NPL limits for EOT-based devices and stimulate systematic studies of disorder compensation designs.

The use of glasses doped with PbS nanocrystals as intracavity saturable absorbers for passive Q-switching and mode locking of c-cut Nd:Gd0.7Y0.3VO4, Nd:YVO4, and Nd:GdVO4 lasers is investigated. Q-switching yields pulses as short as 35 ns with an average output power of 435 mW at a repetition rate of 6–12 kHz at a pump power of 5–6 W. Mode locking through a combination of PbS nanocrystals and a Kerr lens results in 1.4 ps long pulses with an average output power of 255 mW at a repetition rate of 100 MHz.

We present experimental results on transmission of signals in analog fiber-optic links with direct and external intensity modulation and direct detection of the optical signals at the output of the fiber. We examine harmonic distortions of the signals and explore the origin of these distortions. Theoretical interpretation of the experimental results is presented.

We present experimental results on transmission of signals in analog fiber-optic links with direct intensity modulation and direct detection of photocurrent at the output of the fiber. Dispersion compensating fiber (DCF) is used to compensate for the dispersion accumulated over the length of transmitting fiber. Despite the presence of the residual total dispersion we have observed appreciable mitigation of the depth of signal power dips.

Dielectric nanoparticles, and silicon nanoparticles in particular [1,2], are becoming increasingly promising for various applications in photonics, nonlinear optics, optomechanics, and medicine. Plenty of applications exploit the benefits of low-loss Mie resonances, exhibited in the optical range by silicon nanoparticles with sizes of the order of 200 nm. The frequencies of the resonant Mie modes are determined by the size and shape of the particles. However, many of the fabrication techniques result in a polydisperse mixture of different sizes and shapes, and prompt for a post-processing to provide a uniform output. Having an entirely optical tool for such separation [3,4] is highly desirable for sterile, hazardous or highly dynamic microfluidic environments. Following our recent publication [4], in this contribution we present the calculated optical forces acting on silicon nanoparticles in aqueous environment, analyse their potential for optical sorting in a number of schemes, and discuss the experimental implementation of the proposed methods in our setup. The optical forces acting on silicon nanoparticles are shown to reveal their substantial dependence on the particle size. This dependence results in different velocities of the light-driven drift of the nanoparticles, depending on their size and the frequency of the incident light. We propose to employ these features to realise optical sorting, according to the following scenarios. First, we use two counter-propagating beams of different wavelength, which move particles of different sizes in opposite directions; by varying the intensity ratio between the two beams, different subsets of the particle sizes can be separated. A similar approach has been implemented for plasmonic particles [3]. Second, we suggest to impose two counter-propagating beams upon a uniform flow of a disperse mixture, which results in the particles of different sizes being pushed along different directions in space, so that an efficient angular separation is possible within certain size ranges. Third, we propose an efficient angular separation in an all-optical way, by directing the two beams at an angle. This scenario offers an efficient angular separation without any imposed flow. In this work, we consider two laser beams with wavelengths of 532 and 638 nm. For this particular case, angular sorting scheme provides a unique size-angle dependence, yielding up to 70° span of deflections, in the size ranges of 120–160 nm, 190–220 nm, and a few smaller sets. We demonstrate that the proposed angular sorting techniques are robust against the Brownian motion, requiring a run of about 100 μm to achieve a 10-nm distinction in size, while using moderate (0.1 W) power. Finally, we consider the forces acting on silicon nanoparticles in the evanescent wave illumination and show that the proposed methods can be applied for a broad size dimensions using p-polarised light. [1] Evlyukhin A.B., et al. Nano Lett. 12, 3749–3755 (2012). [2] Kuznetsov A.I., et al. Sci. Rep. 2, 492 (2012). [3] Ploschner M., et al. Nano Lett. 12, 1923–1927 (2012). [4] Shilkin D., et al. ACS Photonics 4, 2312–2319 (2017).

We designed semiconductor metasurfaces comprised of rectangular arrays of all-Si antennas exhibiting sharp transmission dips. The sizes and periodicities of the antennas were shown to control the spectral positions and linewidths of the corresponding antenna resonances. The designed resonant metasurfaces were fabricated on a 600-nm-thick silicon-on-sapphire substrate using electron beam lithography, hard mask deposition, and inductively coupled HBr plasma etching. Multiple areas with different antenna sizes were defined on the same substrate. The samples were characterized with a FTIR system under normal incidence and paraxial beam configuration. The spectra revealed transmission dips in the spectral range of 3–4 μm, with the central wavelengths corresponding to the local simulated field enhancements of Eloc = 10–15. The metasurfaces were irradiated by a train of femtosecond laser pulses from a supercontinuum-based mid-IR optical parametric amplifier (OPA) pumped by a Ti:Sapphire amplifier. The incoming 200 fs mid-IR pulses, centered at 3.6 μm, had a maximum fluence of 60 mJ/cm2. The transmitted third harmonic radiation was refocused on and detected by an InGaAs detector based short wave-IR spectrometer. For pump–probe experiments, the residual near-IR 782 nm beam was split off from the output of the OPA, sent through a delay line, and focused at the sample collinearly to the mid-IR beam. Using a home-built calibrated mid-IR spectrometer based on a blazed diffraction grating and a mid-IR camera (Electrophysics PV320), we observed a pump-dependent blue-shifting and eventual disappearance of the resonant dips, accompanied by the reduction of the third harmonic generation.

It is shown that the processing parameters of electron beams with power up to 6 kW and energy of 60 keV used in electron beam installations can be determined by means of light radiation from drift space. A digital photo camera-assisted technique to obtain an image is described. It is shown that the registered image processing allows one to obtain information on the internal structure of an electron beam. The dependence of focal length on the focusing magnet lens current is obtained. The peculiarities of current density distribution over beam cross section are revealed. It is found that the behavior of the beam current density distribution depends strongly on the conditions of major cathode heating. The proposed method to determine electron beam parameters can be applied to control operation conditions of processing equipment, for example, to find the accuracy of gun adjustment, as well as cathode state, from the behavior of the power density distribution. The obtained dependences of beam parameters on the operating conditions of an electron gun can be used when choosing processing parameters to reduce the quantity of work on experimental optimization of welding conditions.

The design of a reflectometer intended for investigating the reflection and transmission coefficients of components of X-ray optics in the wavelength range of 1–25 nm is described. A Czerny-Turner spectrometer with a planar diffraction grating and parabolic collimators is employed to monochromatize the radiation. The required geometry of the monochromatic probe beam is ensured by means of a toroidal mirror. The X-ray source is laser plasma. The expected average spectral radiation power on the sample under study is on the order of 107 photon/s in the spectral band 0.1 nm. A goniometer provides five and two degrees of freedom of the sample 500 mm in diameter and detector, respectively.

The temporal shaping of femtosecond laser pulses reflected from a one-dimensional plasmonic crystal using a commercially available polymer grating coated with a silver film is experimentally demonstrated by timeresolved measurements of the intensity correlation function. Shaping is achieved by the excitation of surface plasmon-polaritons with a lifetime comparable to the 130 fs laser pulse duration. The variety of data obtained demonstrate the flexible shaping of fs-pulses by delaying, advancing, splitting, broadening, compressing, and changing the topological properties of the pulse with the plasmonic crystals under study.

Thin platinum foils and ribbons of the amorphous alloy Fe77Ni1Si9B13 with fractal surfaces made of unidirectional multiscale surface ripples have been prepared. The surface relief and atomic structure of these foils have been investigated by low-energy electron diffraction, atomic force microscopy, and scanning tunnelling microscopy. It has been shown that Pt foils with a fractal surface relief have the prospect for application as reflective diffraction gratings. A model has been proposed and used to calculate the light scattering on unidirectional rippled surface structures of Pt foils.

It is known that the nonlinear optical properties of photonic nanostructures can be modified substantially due to strong field confinement and optical resonances. In this contribution, we study third-harmonic generation from low-loss subwavelength silicon nanodisks arranged in the form of trimer oligomers with varying distance between the nanoparticles. Each of the nanodisks exhibits both electric and magnetic Mie-type resonances that are shown to affect significantly the nonlinear response. We observe the third-harmonic radiation intensity that is comparable to that of a bulk silicon slab and demonstrate a pronounced reshaping of the third-harmonic spectra due to interference of the nonlinearly generated waves augmented by an interplay between the electric and the magnetic dipolar resonances.