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Using three-dimensional direct laser writing, ordered and disordered photonic woodpile structures have been produced. An ideal woodpile is formed by layers of parallel “logs” turned through 90° with respect to logs of the previous layer. The disorder was specified by a random deviation in the angle with respect to their parallel arrangement in each layer of the woodpile. The quality of samples was tested by scanning electron microscopy. The optical diffraction patterns were studied experimentally on microsamples with different degrees of disorder and structure periods. With an increase in the degree of the disorder, the diffraction patterns changed qualitatively with the preservation of the zero diffraction order and formation of a speckle field pattern by higher diffraction orders.

Photonic structures with hexagonal symmetry have been prepared by the additive technology of two-photon laser lithography, and their optical properties have been investigated. The structure of the samples has been examined using scanning electron microscopy. The calculations have been performed for the optical diffraction in the Born approximation of the scattering theory for structures with a limited number of scatterers. The images formed in the monochromatic light on a flat screen located behind the sample have been calculated. The diffraction patterns on the screen have C6v symmetry and consist of three straight lines intersecting at an angle of 120° and hyperbolas, the number of which is a multiple of six. An important feature of these diffraction patterns is the superstructure, i.e., the partition of straight lines and hyperbolas into individual diffraction reflections, the number of which is determined by the number of scatterers of a particular sample. The results of the experimental investigation of the diffraction patterns completely coincide with the calculated data, including the number and arrangement of the superstructure reflections.

Photonic crystals having a woodpile lattice structure with the lateral sizes of up to 200 × 200 μm and lattice period of 1 to 2 μm have been produced by additive three-dimensional laser lithography. The sample structure has been analyzed by optical and scanning electron microscopy. The ideal woodpile consists of “logs” with a rectangular cross section but, in the synthesized structures, the angles are rounded. Calculations of the photonic band structure of woodpiles, in which the cross sections of logs are specified by the Lame curves, have made it possible to estimate the influence of the rounding on the optical properties. Due to significant sample sizes, patterns of optical diffraction in white and monochromatic light have been studied experimentally. The experimental results have been interpreted using calculations of diffraction patterns in the Born approximation of scattering theory.

The effect of invisibility of a finite homogeneous dielectric cylinder due to a substantial decrease in the scattering of electromagnetic waves in specific spectral ranges has been investigated theoretically. A regime of invisibility of the cylinder in an air space without additional cloaking devices has been considered. The effect is based on the resonance suppression of scattered waves, which makes the cylinder invisible to an observer located at any point of the space. The invisibility condition is determined by the Fano resonance between the re-emitted Mie modes and the nonresonant scattering by the cylinder. The dependence of the spectra of the total scattering cross section on the ratio between the length and radius of the cylinder has been analyzed in detail. It has been shown that the transition from the model infinite cylinder to the cylinder of finite length is accompanied by the appearance of new resonances and additional scattering, which, however, does not disturb the lowest frequency region of invisibility at specific length-to-radius ratios of the cylinder.

The modes of laser lithography fabrication of three-dimensional submicrometer structures have been studied. The method is based on the effect of threshold two-photon polymerization of a photosensitive material at the laser beam focus. To determine the lithograph workspace in the coordinates “laser power-speed of the sample displacement with respect to the laser focus,” a series of photonic crystals with the woodpile structure is prepared. Two methods for fabricating three-dimensional structures, i.e., raster scanning and vector graphics (or the vector method) are analyzed in detail. The advantages of the vector method for fabricating periodic structures are demonstrated using crystals of inverted yablonovite as an example. The prepared samples are studied by scanning electron microscopy.

The photon properties of two-dimensional periodic structures formed by infinite homogeneous dielectric cylinders packed in a square lattice have been investigated theoretically. Depending on the dielectric contrast between the cylinders and the surrounding medium, the photonic band structure, transmission spectra of crystals with a finite number of layers, and spectra of Mie scattering by an isolated cylinder have been calculated. The calculations have been performed for the TE polarization. The transformation of photonic stop-bands corresponding to Bragg and Mie resonances has been analyzed using the obtained data. The main effect consists in “castling” energy positions of the Bragg stop-bands and Mie stop-bands. For low-contrast photonic crystals, the low-frequency region of the energy spectrum is determined by Bragg stop-bands, and Mie stop-bands are located higher in energy. With an increase in the dielectric contrast, the energy of Mie stop-bands decreases, and they intersect the region of Bragg stop-bands weakly varying in the TE polarization and form the low-energy region of the spectrum.

The interference nature of resonant Mie scattering, which is described within the Fano model, has been demonstrated. The interference is caused by interaction of an incident electromagnetic wave with reemitted waves that correspond to eigenmodes of a scattering particle. Mie scattering due to the interference can be represented in the form of cascades of resonance lines of different shapes, each of which is described by the classical Fano formula. The effect is observed in resonant light scattering by an arbitrary body of revolution and discussed in detail using the example of scattering by an infinite homogeneous dielectric cylinder.

This paper reports on the synthesis of glassy nanostructures in which the framework is a face-centered cubic lattice of inverse yablonovite with a disordered glassy superstructure. The synthesis has been performed by the direct laser writing method based on two-photon polymerization of a photosensitive material. The fabricated structures have been investigated using scanning electron microscopy. A theoretical calculation of the photonic band structures of the direct yablonovite and the inverse yablonovite has been carried out.

This paper reports on an experimental and theoretical investigations of the possibility of selectively controlling the intensity of {hkl} diffraction reflections in synthetic opals. The calculations of the photonic stop-band width for low-contrast multi-component photonic crystals argue for a selective pattern of the vanishing of various {hkl} stop bands (and, accordingly, of the various {hkl} diffraction reflections) under variation of the dielectric permittivity of one of the components. Optical diffraction patterns have been studied visually and recorded in various scattering geometries with bulk opal samples illuminated by white unpolarized light. The experiments have made use of immersion spectroscopy, a method reducing essentially to successive measurements of diffraction patterns under variation of the dielectric permittivity of the liquid filler of the opal matrix. The {111} and {220} Bragg reflections have been observed to weaken noticeably at the filler permittivities matching very well with the values derived earlier from an analysis of transmission spectra.

The phenomenon of multiple Bragg diffraction in low-contrast photonic crystals based on synthetic opals has been studied both experimentally and theoretically. The transmission and reflection spectra of opal films near the K point of the Brillouin zone of the face-centered cubic lattice in s-polarization exhibit the effect of anticrossing of dispersion curves corresponding to the (111) and \((\bar 111)\) photonic stop bands. The effect of quasi-Brewster suppression of stop bands is clearly pronounced in p-polarization. The experimental data are analyzed using the calculation of the band structure of opal with the inclusion of the polarization of incident light.

This paper reports on experimental and theoretical investigations of light diffraction from thin films of synthetic opal. The diffraction patterns have been studied visually and recorded in different scattering geometries with the films illuminated with white unpolarized light. The diffraction pattern obtained with the film illuminated with a light beam along the [111] axis, which is normal to the film surface, has C 6 symmetry and consists of six strong reflections arranged symmetrically with respect to the incident beam. This pattern becomes substantially more complicated when the film is illuminated by white light at an arbitrary angle to the [111] axis. An experimental study of the spectral response and angular relations of the diffraction patterns has established a fairly full pattern of transformation of diffraction reflections obtained under variation of the angle of light incidence on an opal film. The remarkably good matching of experimental and calculated data provides compelling evidence for light diffraction from thin opal films being two-dimensional.

A comprehensive theoretical investigation of the stop-band switching in two-dimensional multicomponent photonic crystals is carried out. The calculations are performed within the analytical model based on analysis of the scattering form-factor. Earlier, this approach was used to describe experimental data obtained in a study of synthetic opals representing three-dimensional photonic crystals. We report here on the development of a new version of this model applicable to the class of two-dimensional photonic crystals. The existence of resonant (non-switchable) stop-bands and the possibility of selectively controlling light flows propagating at different wavelengths is predicted. These effects draw up new guidelines for the design of two-dimensional photonic crystals possessing desired optical qualities.

The paper reports on a comprehensive study of the statistical characteristics of an ensemble of a-SiO2 particles in synthetic opals. The results of processing of the electron microscopy images obtained in the investigation of the (111) growth layer are presented. To calculate the statistical parameters, an algorithm is developed which permits determination of the diameters of a-SiO2 particles and coordinates of their centers. The algorithm is based on the pattern recognition procedure of objects with radially symmetric boundaries by means of a transformation of the original image similar to the Hough transformation. Our image processing study yields structural parameters of the (111) growth layer, more specifically, the average particle diameter, ∼316 nm, the distribution profile half-width, ∼7%, and the average distance between the centers of neighboring particles, ∼315 nm. The results of the opal image processing are compared with data of optical experiments.

This paper reports on a comprehensive immersion spectroscopy study of the spectral position and profile of the dip corresponding to the (111) photonic band in the transmission spectra of synthetic opals. The variation in the opal-filler permittivity contrast in the region of the immersion-mediated disappearance of the (111) band has revealed its anomalous abrupt behavior. The width of the (111) photonic band at the L point of the Brillouin zone of the fcc lattice has been calculated as a function of the opal-filler permittivity contrast in the plane wave approximation. The experimentally observed (111) dip width is found to be substantially larger than that obtained in the calculations, which can be due to deviations in the size and dielectric parameters of the a-SiO2 particles making up synthetic opals.

The mechanism of recovery of the strength and strain characteristics of neutron-irradiated metals and alloys (up to their initial values observed prior to irradiation) during periodic quenching in the temperature range below the irradiation temperature is considered. It is assumed that the removal of radiation-induced defects (interstitial and vacancy loops) from radiation-hardened metals is associated with the formation of defect-free channels along the slip planes (the phenomenon of dislocation channeling) under the thermal stresses arising in each cycle of quenching. The relationships describing both the kinetics of the decrease in the yield strength σY and in the ultimate strength σU and the kinetics of the increase in the uniform strain eU of a preliminarily irradiated material with increasing number of quenching cycles are derived using the equations of dislocation kinetics. The theoretical results obtained are compared with experimental data on the kinetics of recovery of the mechanical properties of neutron-irradiated samples (the austenitic FeNiCr and ferritic FeCrMo structural steels and the titanium alloy TiAlZr) in the course of periodic quenching.

Corrosion precursors in the form of microgrooves appearing on the elastically compressed surface of a silicon plate under etching are investigated. No corrosion precursors are observed on the elastically stretched surface. This distinguishes the observed effect from corrosion cracking of metals, during which corrosion usually takes place on stretched surfaces. The general dynamic model proposed for the evolution of surface microgrooves during etching, corrosion, and growth of elastically stressed solids is based on the concept of two local etching (growth) rates which are linear functions of the local stress tensor. The model describes the kinetics of the process, and the asymmetry of corrosion evolution to the deformation sign. The role of stacking faults, dislocations, and artificially created surface steps in the evolution of corrosion in stressed silicon crystals is studied.

Electron spin resonance has been used to study the depth distribution of point defects in Si samples bombarded by N5+ (E=16 MeV) and Si5+ (E=26.8 MeV) ions at 175 and 300 K in the dose range (4–8)×1015 cm−2. It was established that unlike the implantation of moderate-energy Si ions (E ∼ 100 keV), the depth distributions of planar tetravacancies in samples bombarded by ions at 300 K under these conditions have two maxima. The experimental results indicate that the tetravacancy density maximum closer to the surface is formed as a result of secondary defect formation processes. No continuous amorphous layer was observed in the bulk of any of the Si samples. This experimental observation is evidence of defect annealing which takes place when high-energy ions are implanted in Si.