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In this work, we use a special nonlinear dependence of dielectric permittivity to study theoretically the effect of a decrease in the nonlinear response in near-surface layers of a medium, which occurs with an increase in the ampl...
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In this work, we use a special nonlinear dependence of dielectric permittivity to study theoretically the effect of a decrease in the nonlinear response in near-surface layers of a medium, which occurs with an increase in the amplitude of the electric field. We propose a model of nonlinearity in which the Kerr-type nonlinearity abruptly disappears with an increase in the field, and the dielectric permittivity becomes constant and independent of the field. Increasing the electric field leads to the formation of a local zone (optical domain) near the surface with linear optical properties where the dielectric permittivity becomes independent of the electric field. We formulate a nonlinear equation with stepwise dependence of the dielectric permittivity on electric field, and obtain its two types of exact solutions corresponding to the surface waves in media with positive (self-focusing) and negative (defocusing) nonlinear responses. We calculate and analyze the total power flows of thesurface waves of both types. We discuss in detail the features of the obtained solutions in comparison with previously published results. It is shown that the choice of a crystal with an appropriate nonlinear response makes it possible to increase or decrease the field intensity near the crystal surface with practically the same thickness of the near-surface layer with altered optical properties.
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In the present paper, we describe theoretically the disappearance of self-focusing nonlinear response in the layers near the crystal surface with totally shielding cover due to the electric field variation. The regularities of the...
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In the present paper, we describe theoretically the disappearance of self-focusing nonlinear response in the layers near the crystal surface with totally shielding cover due to the electric field variation. The regularities of the formation of a linear near-surface layer due to an increase in the field strength are described. The five types of surface waves from nonlinear wave equation satisfying five different sets of boundary conditions are found. The power flows carried by surface waves are calculated for each type of waves in order to analyze the energy redistribution that occurs in the near-surface layers due to the wave propagation. It is found that the redistribution of the surface wave energy between the crystal regions is possible by varying the surface amplitude, surface gradient or gradient of the field at the domain boundary.
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Abstract We consider the contact of a medium in which the refractive index linearly decreases depending on the distance to a nonlinear medium, where the sign of the Kerr nonlinearity can change abruptly when the electric-field str...
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Abstract We consider the contact of a medium in which the refractive index linearly decreases depending on the distance to a nonlinear medium, where the sign of the Kerr nonlinearity can change abruptly when the electric-field strength reaches a threshold value. It is established that surface waves of three types can propagate along such a contact, depending on the sign of the nonlinearity and the range of values of the effective refractive index. Explicit analytical expressions are obtained for the distribution of the electric-field strength in the transverse direction with respect to the contact plane, which are exact solutions of the formulated nonlinear equations. It is shown that the formation of electric-field distributions corresponding to waveguide modes with several intensity maxima is possible in the layer with a refractive-index gradient.
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The disappearance of defocusing nonlinearity near the crystal surface covered by a completely screening thin film due to the varying electric field strength is described. The presence of a screening coating on the crystal surface ...
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The disappearance of defocusing nonlinearity near the crystal surface covered by a completely screening thin film due to the varying electric field strength is described. The presence of a screening coating on the crystal surface allows to find five modes of excitation of surface waves corresponding to solutions of the nonlinear wave equation satisfying five different sets of boundary conditions. The wave parameters and the power flux carried by surface waves are calculated for all five modes.
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The contact of a medium characterized by Kerr nonlinearity and a medium characterized by a stepwise nonlinearity, where the dielectric permittivity depends on the amplitude of the electric field strength, is considered. It is foun...
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The contact of a medium characterized by Kerr nonlinearity and a medium characterized by a stepwise nonlinearity, where the dielectric permittivity depends on the amplitude of the electric field strength, is considered. It is found that an optical domain of finite thickness is formed. Two new types of surface waves are described. The influence of the switching field on the intensity distribution across the interface and on total power flow is analyzed. The intensity at the interface in the case of contact with a nonlinear focusing medium can be maximal, in contrast to the case of contact with a linear medium where the intensity at the interface could not be maximal. The total power flow monotonically decreases with an increase in the nonlinearity parameter and it takes the minimum value at a specific value of the switching amplitude. The largest fraction of the power flow is concentrated on the right side of the optical domain for small values of the switching field starting from a certain value.
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In this paper, we explore transverse electric surface waves propagating along the crystal with jump change of Kerr nonlinearity in dependence on field amplitude. The dielectric permittivity in the proposed model of nonlinearity is...
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In this paper, we explore transverse electric surface waves propagating along the crystal with jump change of Kerr nonlinearity in dependence on field amplitude. The dielectric permittivity in the proposed model of nonlinearity is characterized by abruptly changing unperturbed dielectric constant and Kerr nonlinearity coefficient from one value to another when field amplitude exceeds the threshold value of the switching field. This allows to find exact solutions of model equations in different cases of nonlinearity signs, and to obtain the dependence of wave characteristics, including total power flux, on effective refractive index in explicit form. Such solutions describe two new types of nonlinear surface waves with specific structure depending on electric field amplitude. We derive the conditions of surface domain formation. It is found that the largest percentage of radiation is concentrated within the domain. (C) 2020 Elsevier B.V. All rights reserved.
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The theoretical description of the change in optical properties of nonlinear crystal along the surface caused by the propagation of localized excitations is proposed. The nonlinear response sharp changes between focusing and defoc...
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The theoretical description of the change in optical properties of nonlinear crystal along the surface caused by the propagation of localized excitations is proposed. The nonlinear response sharp changes between focusing and defocusing depending on field amplitude. We derive new types of surface states characterized by composite structure consisting of three parts. The influence of interaction of excitations with crystal surface on structure of the nonlinear surface states and peculiarities of the surface domain formation is analyzed. The new features of localization, which appear when the nonlinear response changes between self-focusing and defocusing, are described.
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We consider self-focusing nonlinear optical crystal separated by linear dielectric plate. The nonlinear crystals are characterized by an abruptly changing dielectric permittivity and Kerr nonlinearity coefficients in dependence on...
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We consider self-focusing nonlinear optical crystal separated by linear dielectric plate. The nonlinear crystals are characterized by an abruptly changing dielectric permittivity and Kerr nonlinearity coefficients in dependence on electric field amplitude. Two new types of the transverse electric nonlinear surface waves propagating along the layers are found. The field distributions and characteristics of nonlinear surface waves are obtained in exact analytical form. The structure of nonlinear surface waves and condition of existence were analyzed in dependence of effective refractive index and the plate thickness.
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We theoretically investigate the composite three-layered structure (waveguide) consisting of linear dielectric core inside defocusing nonlinear optical crystal. We assume that the abrupt change in dielectric permittivity and Kerr ...
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We theoretically investigate the composite three-layered structure (waveguide) consisting of linear dielectric core inside defocusing nonlinear optical crystal. We assume that the abrupt change in dielectric permittivity and Kerr nonlinearity coefficients occurs in dependence on electric field amplitude. The theory described the regulating changes in the optical properties of crystal due the intense light beam propagation is proposed. We solve the problem of eigen modes of such three-layered structure. We find two new types of the transverse electric nonlinear surface waves. Such waves are characterized by the special structure consisting of three parts. The orders waveguide modes in dependence on the number of amplitude maxima inside the core are determined. We analyze the influence of the waveguide core thickness and its optical characteristics on the structural parameters of surface waves.
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The models of nonlinear wave and diffusion processes with the stepwise change in equation coefficients in dependence of the solution amplitude and with non-fixed boundaries are proposed. The exact non-smooth solutions of the probl...
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The models of nonlinear wave and diffusion processes with the stepwise change in equation coefficients in dependence of the solution amplitude and with non-fixed boundaries are proposed. The exact non-smooth solutions of the problems formulated are found. The positions of the boundary between the regions where the solutions are greater than the threshold value of the switching field and the regions where the solutions are less than the threshold value of the switching field are calculated. This position for the diffusion processes determines the phase transition boundary. It is proposed to use the calculated positions of the phase transition boundaries to estimate the diffusion coefficients by the experimentally determined parameters. The new formulations of the problems with non fixed boundaries describing the nonlinear steady-state diffusion processes are considered in different geometry system. The various cases of diffusion regimes at the boundaries were studied analytically in each system.(c) 2021 Elsevier B.V. All rights reserved.
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