Dyakonov Surface Waves Research Articles

Spin Photonics‐Based on a Twinning Hyperbolic Metamaterial

AbstractRouting and multiplexing of the optical surface waves are critical for the ultra‐compact nano‐photonic systems. Given this background, traditional metal‐based systems, despite of the ability of supporting the surface plasmon polariton propagation, are constrained on manipulations due to the optical isotropy, and artificially designed structures are always required at the input or output to help attain the additional selectivity. Here, a spin‐dependent multi‐channel scheme is proposed based on the modulation ability of the hyperbolic metamaterial's anisotropy on Dyakonov Surface Waves. The input coupling, propagation direction, as well as the output coupling of the optical single are well determined by the certain spin feature carried by the light and the orientation of the interface's anisotropy because of the spin‐momentum locking. Specially, by constructing a twinning hyperbolic metamaterial, which contains the structural symmetry and materials symmetry, a photonic chip with 4 routing channels are demonstrated experimentally, where the spin of an incident beam can be maintained during the propagation on‐chip and then delivered back into the free space, offering a new planar scheme for metamaterial‐based spin‐controlled nano‐photonic applications.

Dyakonov surface waves in a thin interfacial waveguide formed by negatively anisotropic dielectrics.

Dyakonov surface waves (DSWs) are electromagnetic surface waves that exist at the interface of two dissimilar materials, with at least one material being anisotropic. Although there are various types of these waves, they all exist in anisotropic materials with positive anisotropy. The requirement for positive anisotropy limits the choice of materials that can support these waves. In this study, we present a type of Dyakonov surface wave that occurs at the interface of negatively anisotropic materials. Specifically, we demonstrate their existence in a system consisting of two negatively anisotropic slabs confined between two perfect electric conductor (PEC) walls. By assuming a small distance between the walls, we derive analytical expressions for the propagation constant, penetration depth, and field distribution of these surface waves. We numerically demonstrate that these surface waves can also exist in structures beyond the approximations used to develop the theoretical framework. The existence of Dyakonov surface waves in negative crystals broadens the range of materials suitable for their practical implementation.

Dyakonov surface waves in dielectric crystals with negative anisotropy

Abstract Since the initial discovery of Dyakonov surface waves at a flat infinite interface of two dielectrics, at least one of which is positively anisotropic, extensive research has been conducted towards their theoretical and experimental studies in materials with positive anisotropy. The potential applications of these waves were initially limited due to the stringent conditions for their existence and the requirement for position anisotropy. In our study, we present the theoretical prediction and experimental observation of a novel type of Dyakonov surface waves that propagate along the flat strip of the interface between two dielectrics with negative anisotropy. We demonstrate that the conditions for surface waves are satisfied for negatively anisotropic dielectrics owing to the specific boundaries of the strip waveguide confined between two metallic plates. We study such modes theoretically by using the perturbation theory in the approximation of weak anisotropy and demonstrate that the electromagnetic field distribution in these modes is chiral. Experimental verification of theoretical predictions is made in the microwave range using 3D-printed negatively anisotropic water-dielectric metamaterial slabs. The existence of Dyakonov surface waves in negative crystals prompts a reassessment of the list of materials suitable for practical realization of these waves in the visible and infrared ranges. Due to the ability of the considered modes to transmit chiral light, they have potential in the sensing of chiral organic molecules.

Dyakonov Surface Waves at the Boundary of Anisotropic Biaxial Crystals

Dyakonov Surface Waves at the Boundary of Anisotropic Biaxial Crystals

Thermally tunable Dyakonov surface waves in semiconductor nanowire metamaterials

The development of engineered metamaterials has enabled the fabrication of tunable photonic devices capable of manipulating the characteristics of electromagnetic surface waves. Integration of semiconductors in metamaterials is a proven approach for creating thermally tunable metamaterials through temperature control of the semiconductor carrier density. In this paper, an interface consisting of an isotropic dielectric material as a cover and an indium antimonide (InSb) nanowire metamaterial as a substrate, is theoretically introduced to investigate the propagation conditions of Dyakonov surface waves in terahertz (THz) frequencies. Various temperature-dependent properties of Dyakonov surface waves in such a geometry is studied, including allowed THz regions, angular existence domain, dispersion relation, directionality, localization degree and figure of merit. The proposed configuration due to the presence of significant birefringence in InSb nanowire metamaterial, has potential applications in THz sensing, imaging and spectroscopy.

Grating-coupled excitation of high-phase-speed Dyakonov surface waves

Excitation of high-phase-speed Dyakonov surface waves guided by a surface-relief grating made of a uniaxial dielectric material was theoretically studied using the rigorous coupled-wave approach for illumination by p - and/or s -polarized plane waves. The absorptance at a fixed value of the free-space wavelength was plotted against the polar angle of incidence, and absorptance peaks were correlated with the solution of the dispersion equation of the underlying canonical boundary-value problem for Dyakonov-surface-wave propagation. Both p - and s -polarized plane waves can excite the high-phase-speed Dyakonov surface waves. No, one, or multiple excitations of high-phase-speed Dyakonov surface waves are possible, depending upon the structural parameters of the grating. Excitation of a high-phase-speed Dyakonov surface wave as a specular Floquet harmonic also appears possible.

Spin-Dependent Visible Dyakonov Surface Waves in a Thin Hyperbolic Metamaterial Film.

A Dyakonov surface wave offers a promising way of guiding light in two dimensions with almost no loss but also additional freedom of modulation through the anisotropy at the interface. Here we experimentally demonstrated a spin-dependent Dyakonov surface wave mode propagating in a hyperbolic metamaterial film at a visible frequency. Due to the strong anisotropy of the hyperbolic metamaterial, a Dyakonov type mode shows a large allowed angle band and transverse spin with its direction determined by the orientations of the hyperbolic anisotropy and surface normal, based on which we experimentally observed the photonic spin Hall effect of the surface wave mode. This work enables a new generation of two-dimensional photonic circuits with spin-dependent excitation/detection and modulation devices at the subwavelength level.

Surface Dyakonov\u2013Cherenkov radiation

Recent advances in engineered material technologies (e.g., photonic crystals, metamaterials, plasmonics, etc.) provide valuable tools to control Cherenkov radiation. In all these approaches, however, the particle velocity is a key parameter to affect Cherenkov radiation in the designed material, while the influence of the particle trajectory is generally negligible. Here, we report on surface Dyakonov–Cherenkov radiation, i.e. the emission of directional Dyakonov surface waves from a swift charged particle moving atop a birefringent crystal. This new type of Cherenkov radiation is highly susceptible to both the particle velocity and trajectory, e.g. we observe a sharp radiation enhancement when the particle trajectory falls in the vicinity of a particular direction. Moreover, close to the Cherenkov threshold, such a radiation enhancement can be orders of magnitude higher than that obtained in traditional Cherenkov detectors. These distinct properties allow us to determine simultaneously the magnitude and direction of particle velocities on a compact platform. The surface Dyakonov–Cherenkov radiation studied in this work not only adds a new degree of freedom for particle identification, but also provides an all-dielectric route to construct compact Cherenkov detectors with enhanced sensitivity.

Dyakonov Surface Waves at the Boundary of Anisotropic Biaxial Crystals

A general approach to analysis of Dyakonov surface waves at the interfaces of anisotropic biaxial crystals is proposed, taking into account arbitrary spatial orientation of the media tensors principal axes. This approach is based on the operator representation of macroscopic Maxwell equations corresponding to the quantum-mechanical equations for photon states in an inhomogeneous anisotropic media. Surface wave dispersion law is investigated in the most general case. It is established that the interface eigenmode dispersion is closely related to the dispersion of bulk waves in the partnering media, which is a specific feature of Dyakonov waves. The electromagnetic field spatial distribution is investigated in the direction orthogonal to the boundary plane. The surface wave angular existence domain is determined. It's dependencies on the rotation angles of the media optical axes are studied as well. Keywords: electromagnetic surface waves, interface photon states, anisotropic media, biaxial materials.

Поверхностные электромагнитные волны Дьяконова на границе раздела анизотропных двуосных кристаллов

A general approach to analysis of Dyakonov surface waves at the interfaces of anisotropic biaxial crystals is proposed, taking into account arbitrary spatial orientation of the media tensors principal axes. This approach is based on the operator representation of macroscopic Maxwell equations corresponding to the quantum-mechanical equations for photon states in an inhomogeneous anisotropic media. Surface wave dispersion law is investigated in the most general case. It is established that the interface eigenmode dispersion is closely related to the dispersion of bulk waves in the partnering media, which is a specific feature of Dyakonov waves. The electromagnetic field spatial distribution is investigated in the direction orthogonal to the boundary plane. The surface wave angular existence domain is determined. It’s dependencies on the rotation angles of the media optical axes are studied as well.

Investigation of the existence domain for Dyakonov surface waves in the Sage computer algebra system

Surface electromagnetic waves (Dyakonov waves) propagating along a plane interface between an isotropic substance with a constant dielectric constant and an anisotropic crystal, whose dielectric tensor has a symmetry axis directed along the interface, are considered. It is well known that the question of the existence of such surface waves is reduced to the question of the existence of a solution to a certain system of algebraic equations and inequalities. In the present work, this system is investigated in the Sage computer algebra system. The built-in technique of exceptional ideals in Sage made it possible to describe the solution of a system of algebraic equations parametrically using a single parameter, with all the original quantities expressed in terms of this parameter using radicals. The remaining inequalities were only partially investigated analytically. For a complete study of the solvability of the system of equations and inequalities, a symbolic-numerical algorithm is proposed and implemented in Sage, and the results of computer experiments are presented. Based on these results, conclusions were drawn that require further theoretical substantiation.

Theory of grating-coupled excitation of Dyakonov surface waves (Erratum)

Theory of grating-coupled excitation of Dyakonov surface waves (Erratum)

The Study of the Surface Plasmon Polaritons at the Interface Separating Nanocomposite and Hypercrystal

Surface plasmon polaritons (SPPs) propagating at the interfaces of composite media possess a number of fascinating properties not emerging in case of conventional SPPs, i.e., at metal-dielectric boundaries. We propose here a helpful algorithm giving rise for investigation of basic features of complex conductivity dependent SPPs at the interface separating nanocomposite and hypercrystal. The main goal of the work is to investigate dispersion of the SPPs propagating at the boundary separating two different media. Aiming to achieve the aforementioned goal that the effective Maxwell Garnett model is used. It is demonstrated that the SPPs dispersive properties are dramatically affected by the material conductivity. Correspondingly, the filling ratio of the nanoparticles in the composite and their dielectric properties also allow one to engineer characteristics of the SPPs. Having a deep insight into the conductivity dependent functions, we concluded, on their behavior for the case of hyperbolic regime and Dyakonov surface waves case. Our model gives rise for studying features of surface waves in the complex conductivity plane and provides more options to tune the fundamental features of SPPs at the boundaries correlated with composite media.

Singular existence of a Dyakonov–Voigt surface wave: Proof

If Dyakonov surface-wave (DSW) propagation can be guided by the planar interface of an isotropic dielectric medium and a uniaxial dielectric medium with its optic axis lying wholly in the interface plane, then a Dyakonov–Voigt surface wave can propagate in at most one direction within the angular sector for DSW propagation.

Numerical analysis of Dyakonov surface-wave propagation at the interface of anisotropic and gyrotropic media

The propagation of Dyakonov surface waves was numerically investigated for the interfaces of two biaxial anisotropic media. Variation of the propagation direction changes the field energy localization from one of the partnering media to another. It is possible to find a specific propagation direction, which is characterized by the strongest energy localization in the boundary plane. This direction corresponds to the central angle of the angular existence domain. On the other hand, variation of the components of the media permittivity tensor, including the introduction of gyrotropy, changes the possible propagation directions, which is a potential way to control surface eigenmodes.

High-phase-speed Dyakonov surface waves

The canonical boundary-value problem for Dyakonov-surface-wave propagation in a fixed direction guided by the planar interface of a uniaxial dielectric material and an isotropic nondissipative dielectric material was solved. Both partnering materials were taken to be homogeneous and the constitutive parameters for both to lie within the ranges of available materials. Solutions were found for which the phase speed of the Dyakonov surface wave is greater than the phase speed of a plane wave in the bulk isotropic partnering material.

Tunable Dyakonov surface waves in graphene-hBN hyperstructure

Here we analyze the propagation of Dyakonov surface waves(DSWs) at the interface between isotropic dielectric material and graphene-hBN hyperstructure (GhH) whose physical properties and optical topological transition regions can be controlled by varying the Fermi energy level of graphene sheets via electrostatic biasing. Various properties of the DSWs supported at the interface have been theoretically investigated, including the confinement factor and the polarization hybridization factor. By analyzing the electric-field intensity distribution of the DSWs excited by the linearly polarized dipole, it is found that the propagation direction of the DSWs can be controlled by the chemical potential of graphene. It is shown that the GhH supporting the DSWs with high wavenumber allows the enhanced amplitude of the spontaneous emission rate (SER) for one emitters to be flexibly controlled by the voltage applied to graphene.

Dimensional confinement and waveguide effect of Dyakonov surface waves in twisted confined media

Abstract We theoretically study Dyakonov surface waveguide modes that propagate along the planar strip interfacial waveguide between two uniaxial dielectrics. We demonstrate that owing to the one-dimensional electromagnetic confinement, Dyakonov surface waveguide modes can propagate in the directions that are forbidden for the classical Dyakonov surface waves at the infinite interface. We show that this situation is similar to a waveguide effect and formulate the resonance conditions at which Dyakonov surface waveguide modes exist. We demonstrate that the propagation of such modes without losses is possible. We also consider a case of two-dimensional confinement, where the interface between two anisotropic dielectrics is bounded in both orthogonal directions. We show that such a structure supports Dyakonov surface cavity modes. Analytical results are confirmed by comparing with full-wave solutions of Maxwell’s equations. We believe that our work paves the way toward new insights in the field of surface waves in anisotropic media.

Dyakonov-like waveguide modes in an interfacial strip waveguide

We study Dyakonov surface waveguide modes in a waveguide represented by an interface of two anisotropic media confined between two air half-spaces. We analyze such modes in terms of perturbation theory in the approximation of weak anisotropy. We show that in contrast to conventional Dyakonov surface waves that decay monotonically with distance from the interface, Dyakonov waveguide modes can have local maxima of the field intensity away from the interface. We confirm our analytical results by comparing them with full-wave electromagnetic simulations. We believe that this work can bring new ideas in the research of Dyakonov surface waves.

Two Dyakonov\u2013Voigt surface waves guided by a biaxial\u2013isotropic dielectric interface

Electromagnetic surface waves guided by the planar interface of an orthorhombic dielectric material and an isotropic dielectric material were analyzed theoretically and numerically. Both naturally occurring minerals (crocoite, tellurite, and cerussite) and engineered materials were considered as the orthorhombic partnering material. In addition to conventional Dyakonov surface waves, the analysis revealed that as many as two Dyakonov–Voigt surface waves can propagate in each quadrant of the interface plane, depending upon the birefringence of the orthorhombic partnering material. The coexistence of two Dyakonov–Voigt surface waves marks a fundamental departure from the corresponding case involving the planar interface of a uniaxial dielectric material and an isotropic dielectric material for which only one Dyakonov–Voigt surface wave is possible. The two Dyakonov–Voigt surface waves propagate in different directions in each quadrant of the interface plane, with different relative phase speeds and different penetration depths. Furthermore, the localization characteristics of the two Dyakonov–Voigt surface waves at the planar interface are quite different: the Dyakonov–Voigt surface wave with the higher relative phase speed is much less tightly localized at the interface in the isotropic dielectric partnering material.