The properties of Bessel beams propagation and transformation in optical metamaterials are studied. The problem is
solved by reflection and refraction of vectoral BLB containing embedded vortices on the boundary of a usual medium
and metamaterial. The reflection and refraction coefficients of arbitrary Bessel beam are represented as superposition of
linear combinations of reflection and refraction ones of TM- and TE- polarized Bessel beams. The possibility is established and conditions are determined for unidirectional and opposite directional propagation of Bessel light beams (BLBs) phase and the longitudinal component of its energy flux in metamaterials.
A new method of high-effective generation of Bessel vortices from zero-order Bessel beam in one-dimensional photonic
crystal is proposed and elaborated. The influence of parameters of the structure and incident beam on this process is analyzed.
A new method of formation and spatial separation of radially and azimuthally polarized Bessel beams containing phase
dislocation (Bessel vortex) is proposed. This method is based on using one-dimensional photonic crystal. It has been
shown that on the bases of these structures effective and compact generators for radially and azimuthally polarized Bessel
beams can be elaborated.
The properties of transformation of a supershort light pulse with arbitrary temporal form in dispersive media in the third approximation of the dispersion theory are investigated. The special attention is devoted to the cases having practical importance, for example, when temporal form of the pulse is described by the function of hyperbolic secant. It is shown that in the spectral region of 'zero' dispersion owing to the influence of dispersive effects of the third order the deformation of envelope of the pulse takes place, namely: the maximum of the envelope is decreased, shifted and the satellite appears.
The space-time dynamics of a pulsed Bessel beam envelope behind the axicon is studied in detail theoretically and experimentally.
It has been discovered and explained the phenomenon of appearance of an additional pulsed beam (satellite)
behind the axicon. The dependence of the axial intensity of the output diverging femtosecond Bessel beams on the
distance from the axicon has been calculated and measured. It is established that the Bessel pulsed beam diameter increases,
the axial intensity slowly decreases with increasing the longitudinal coordinate, and the zone of existing the
pulsed Bessel beam is very long. It is shown that in schemes with the diverging and converging initial Gaussian pulse
differing in the lens position, one can generate femtosecond Bessel beam with the required parameters (zero-maximum
diameter and intensity) using only a single axicon and a lens.
A new method of forming nondiffracting and nondispersing azimuthally (or radially) polarized pulsed Bessel beams is
suggested. These light fields are promising for photolithography, confocal microscopy, and optical communications. The
method is based on the splitting of a supershort arbitrarily polarized Bessel pulse, which propagates in a one-dimentional
photonic crystal, into two pulses having the mutually orthogonal polarizations.
New methods of forming azimuthally and radially polarized Bessel light beams using a one-dimensional photonic crystal
having photorefractive properties are proposed and elaborated. These light fields are promising for photolithography,
confocal microscopy, and optical communications. The methods are based on the splitting of a polarized Bessel beam,
which propagates in a one-dimensional photonic crystal, into two beams having the mutually orthogonal polarizations.
A new method of formation of radially and azimuthally polarized Bessel light beams has been proposed and experimentally realised. This method is based on interaction of radiation with layered periodic medium, including defect impurity - a layer of an uniaxial material. It has been shown that it is possible to control this process by changing the cone angle of the incident Bessel light beam.
A method of transformation of Bessel light beams (BLBs) with an arbitrary cone angle into beams having radially (ρ-) and azimuthally (φ- ) polarization is suggested and elaborated. This method is based on the use of interaction of radiation with a periodical medium having defect inclusion in the form of an anisotropic layer. It is shown that owing to variation of parameters of defect inclusions one can realise a controllable effect on interference maxima of transmission of the periodical medium. Due to the phase difference of orthogonal polarized eigen waves of in passing through every period of the medium, photonic band gaps (PBGs), corresponding to different eigen waves, are splitting and shifting with respect to each other. Such a shift can result in the overlapping of regions of significant reflection of one eigen mode with a region of high transmission of another eigen wave. This enables one to separate and consequently spatially select radially and azimuthally polarized Bessel light beams. An advantage of the suggested method of formation of ρ- and φ- polarized BLBs is the possibility of its realization for any wavelength. This is easily attained by tuning the cone angle of the incident circularly polarized BLB.
The investigation of physical properties of new relaxor ferroelectric material of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) single crystal has been carried out. It has been established the opportunity of existence of this crystal in two modifications, having tetragonal unit cell (space group P4mm) and cubic perovskite one (space group Pm3m) accordingly. Their lattice parameters were found. It has been established a thermal stability of the PMN-PT single crystals in wide temperature range (20-950°C). The results of optical investigations have shown, that the crystals have good transparency in wide spectral area from the visible to IR range. Dispersion of refractive index of PMN-PT crystal are calculated by the dispersion theory and Kramers-Kronig' relationship. Using interferometry method, extremely large linear electro-optic coefficients r13~33 pm/V and r33~80 pm/V were characterised for the crystal, having tetragonal unit cell. It has been discussed prospects of the material while creating different optical systems.
It is established that imbedding of the defective layers into one-dimensional three-layered periodic structure leads to appearance new photonic band gaps, quantity and width of which are dependent on number of the periods of the structure, located between the next defective layers. It has been obtained that it is possible to achieve omnidirectional reflection from three- layered structure with introduced defects simultaneously at several closely arrange frequency regions.
It has been established that radiation with arbitrary space structure may be presented in the form of superposition of Gauss-Hermit beams. Their parameters are connected with group velocity and curvatures of wave velocity surface. It has been obtained compact expressions determining the beam divergence in crystals with complex anisotropy (natural, induced by external fields, caused by existence of space periodicity of optical properties, gyrotropy). It has been grounded the perspectives of use of media with locally concave regions of wave vector surface for creation of focusing elements. It has been proposed binary focusing-defocusing optical scheme. In the latter light modes, disturbed in biaxial gyrotropic crystal, propagating along optical axis, or in anisotropic medium with periodical non-uniformity, may be used. Switching of modes and, hence, the choice of functional regime (focusing/defocusing) is realized by external polarization system.
We have investigated the influence of cubic optical non- linearity and derivative of group velocity on laser beam divergence by the propagation in 1D photonic crysatl which is layered periodic structure formed by anisotropic media. It has been established that the laser beam divergence is determined by two physical mechanisms: influence of non- linearity and scattering gon diffractional grating appearing in the crysatl because the presence of periodiciity of optical properties. It has been shown that the second mechanism may become the reason of strengthening the focus. We have analyzed the influence of low-frequency electric field on this phenomenon. It has been found the conditions of non-diffractional beam propagation in photonic nonlinear crystal.
It has been shown that conditions and peculiarities of bistable regimes by acoustoelectrooptic interaction in cubic non-centrosymmetrical crystal are determined by presence of gyrotropy. It has been established that more essentially the latter is displaying in doubling of number of bistable regions and in appearance of dependence of conditions for realization of bistable regimes on polarization of incident light wave. It has been obtained the opportunity of change of switching character by reversion of external electric field.
In the present report different configurations of electro- optical interaction in multilayer structures have been analyzed at long-length approach. By this, we considered these structures formed by the components with different kinds of symmetries, namely: 'centrosymmetrical/centrosymmetrical crystals,' 'noncentrosymmetrical/noncentrosymmetrical crystals,' 'centrosymmetrical/noncentrosymmetrical crystals.' It has been found the dependence of effective electro-optical coefficients of a superlattice from electro-optical constants of layers and their width. It has been shown that effective parameters of multilayer heterostructure created by crystal layers of arbitrary symmetry, which was put into external field, depend on the angle between crystallographic axes of the components of superlattice. The range of values of angle was defined for which the changes of effective parameters are unimportant.
It has been analyzed the peculiarities of propagation of weakly and strongly divergent Gaussian beams near optical axes of uniaxial and biaxial crystals. It has been determined the dependence of character of the laser beam transformation by scanning near special directions on optical anisotropy of medium. It has been established that in strongly divergent light beams the presence of anisotropy leads to changes of energy distribution in its cross-section. It has been found the correct conditions of propagation of non-aberrational beams in crystals which take into account the influence of anisotropy. It has been investigated display of gyrotropy in polarization, energetic characteristics and beam divergence of optical radiation.
The peculiarities of propagation of space-limited light beams in a periodic structure formed by crystalline layers of an arbitrary symmetry have been considered. It has been shown, that phenomenon of non-lens focusing may exist even in superlattices made from layers with a high symmetry. The character of changes of the light beams diffraction by decreasing the crystalline layers symmetry until orthorombical one has been analyzed. The influence of mutual orientation of crystallographic axes of layers on the light radiation focusing has been established. The region of X3 axes disorientation for components formed superlattice, for which focusing properties of layered periodic crystalline structures are constant, has been obtained. The optimal characteristics of focusing systems on the base of layered periodic crystalline structures have been found.
The study of multilayer heterostructures is of great interest for the development of materials with new properties. This objective can be achieved by means of crystal combination, which have necessary characteristics. When the length of electromagnetic waves is over the superlattice period, dispersion of vibrations propagating in the heterostructures is insensitive to the phenomenon at the layer boundary and, therefore, superlattice may be considered as homogeneous crystalline medium which characterizes by the set of effective parameters. The expression, which helps to define the effective tensor of dielectric permeability of the multilayer medium disturbed by the electric field of low frequency, has been found. By this, we considered the superlattice formed by crystalline layers of arbitrary symmetry. The properties of multilayer heterostructure have been analyzed at different configurations of electrooptical interaction. The possibility of creating of heterostructures with higher electrooptical efficiency as compared with its forming crystal components has been theoretically approved. The conditions of realization of superlattices, which are insensitive to the value ofexternal electric field, on the basis ofelectrooptical crystals, have been found.
In the present paper the new strict solutions of Maxwell equations and vector wave equation for different modes of an electromagnetic field of nondiffraction beams of a light are obtained. It is shown, that the set of solutions is multiparameter and consequently there is an arbitrariness in choice of main types of modes. The expressions for the polarization characteristics of different Te and TM modes of Bessel beams are obtained. The principle of reciprocity permitting to realize transition from E-modes to M-modes and backward is justified. Their average density of energy and Poynting's vector have been calculated. The main legitimacies of TE and TM modes are established. The obtained results may be used in the description of the transformation of Bessel light beams of different types.
It has been shown that application of cubic gyrotropic crystals permits to extend functional opportunities of nonreciprocal elements on their base at the expense of receipt no one but two regions with essential value of phase nonreciprocity. It has been established that cubic centrally symmetric crystals with electroinduced anisotropy may be used while creating nonreciprocal elements which are controlled by electric field and polarization of the incident light. It has been grounded that anisotropic Bragg diffraction in biaxial crystals may be applied by elaboration of pure phase large-aperture nonreciprocal systems where it may be achieved the absolute absence of diffractional losses. It has been shown the opportunity of application of the double Bragg diffraction in uniaxial gyrotropic crystals (for example, paratellurite) near optic axis while creating pure reciprocal systems which are necessary for ring laser with mode synchronization.
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