Dyakonov Surface Waves Research Articles

Dyakonov surface waves at the interface between hexagonal-boron-nitride and isotropic material

In this paper we analyze the propagation of Dyakonov surface waves (DSWs) at the interface between hexagonal-boron-nitride (h-BN) and isotropic dielectric material. Various properties of DSWs supported at the dielectric-elliptic and dielectric-hyperbolic types of interfaces have been theoretically investigated, including the real effective index, propagation length, the angular existence domain (AED) and the composition ratio of evanescent field components in an h-BN crystal and isotropic dielectric material, respectively. The analysis in this paper reveals that h-BN could be a promising anisotropic material to observe the propagation of DSWs and may have potential diverse applications, such as high sensitivity stress sensing or optical sensing of analytes infiltrating dielectric materials.

A method for detecting Dyakonov surface waves at an interface of two anisotropic media

The possibility of excitation and detection of Dyakonov surface waves at the interface of two identical homogeneous anisotropic media by means of the effect of polarization conversion in reflection is investigated theoretically. Excitation of the Dyakonov wave is uniquely related to a peculiarity in the reflection coefficient near a certain incidence angle determined only by parameters of the medium. The largest effect of conversion is achieved for the crystal plane exhibiting the largest difference of refractive indices.

Electromagnetic surface waves in liquid metacrystals

We study linear electromagnetic waves guided by an interface between a dielectric medium and liquid metacrystal (LMC) as well as by a slab of LMC. We derive the dispersion equation for such waves and find their transverse structure for the arbitrarily oriented anisotropy axis of LMC controlled by an external constant electric field. A high degree of anisotropy can be reached in LMC near the resonance of the inclusions (meta-atoms), and it allows propagation of known Dyakonov surface waves below the resonance frequency and also specific surface modes above the resonance frequency (in the hyperbolic dispersion regime) along the LMC–dielectric interface. Both types of surface waves are characterized by sensitivity to the parameters (radiation frequency, orientation of the optical axis, etc.) and have hybrid (mixed ordinary and extraordinary) polarization. In the LMC slab there can exist two families of eigenmodes: low-k and high-k modes, with the latter arising only in the hyperbolic dispersion regime. In the case when the normal to the slab interface is along the resonance cone generatrix in the LMC, a very high density of eigenmodes can take place that results from the inherent property of the hyperbolic medium—infinite density of photonic states.

Temperature-mediated transition from Dyakonov surface waves to surface-plasmon-polariton waves

The propagation of electromagnetic surface waves, guided by the planar interface of a temperature-sensitive isotropic material and a temperature-insensitive uniaxial material, each characterized by a relative permittivity dyadic, was investigated theoretically for the case of the optic axis of the uniaxial partnering material lying wholly in the interface plane. On raising the temperature, the isotropic partnering material (namely, InSb) transforms from a weakly dissipative dielectric material to a metal in the terahertz frequency regime. Correspondingly, the surface waves change from being Dyakonov surface waves to being surface–plasmon–polariton (SPP) waves. Numerical studies revealed that modest changes in temperature could result in dramatic changes in the numbers of propagating surface waves, their angular existence domains, their propagation constants, and their decay constants. Whereas multiple Dyakonov surface waves may propagate in a specific direction if at least one of the two partnering materials is dissipative, at most one SPP wave can propagate in a specific direction.

3C12 金属ナノ粒子分散液晶メタマテリアルによるDyakonov表面波の存在条件緩和(液晶フォトニクス・光デバイス,口頭発表,2015年日本液晶学会討論会)

3C12 金属ナノ粒子分散液晶メタマテリアルによるDyakonov表面波の存在条件緩和(液晶フォトニクス・光デバイス,口頭発表,2015年日本液晶学会討論会)

Dyakonov surface waves in lossy metamaterials

We analyze the existence of localized waves in the vicinities of the interface between two dielectrics, provided one of them is uniaxial and lossy. We found two families of surface waves, one of them approaching the well-known Dyakonov surface waves (DSWs). In addition, a new family of wave fields exists which are tightly bound to the interface. Although its appearance is clearly associated with the dissipative character of the anisotropic material, the characteristic propagation length of such surface waves might surpass the working wavelength by nearly two orders of magnitude.

Dyakonov surface waves in nanoparticle-dispersed liquid crystal metamaterials

We investigated the conditions necessary for the existence of lossless Dyakonov surface waves (DSWs) on nanoparticle-dispersed liquid crystal (NDLC) metamaterials composed of nematic liquid crystal hosts dispersed with Ag nanoparticle inclusions. The effective dielectric permittivities of the NDLCs were obtained by the extended Maxwell–Garnett mixing rule. We demonstrated that the range of cover refractive indices that could support DSWs could be tuned and significantly expanded, even allowing for air cladding. We also showed that the angular existence domain could be significantly widened. Our approach may open new avenues for exploring practical applications of lossless DSWs with switching capabilities.

Dyakonov hybrid surface waves at the isotropic-biaxial media interface.

Dyakonov surface waves (DSWs) at the interface of an isotropic dielectric material and a biaxial dielectric crystal were considered in the case in which two principal axes of the biaxial crystal lie in the plane of the interface. Both x-cut and y-cut biaxial crystals were considered, and all permittivity scalars were assumed to be real and positive. A rather simple expression to relate the components of the wave vector of a DSW was derived, and analytical expressions for the limit angles at which the DSWs can propagate and the Poynting vector components of the DSWs were obtained. These expressions were numerically investigated for several biaxial materials. Different conditions for the relative permittivity scalars at which the DSWs can exist were identified. As an example, DSWs can exist not only for the positive, but also for the negative y-cut biaxial crystals.

Comparative analysis of Dyakonov hybrid surface waves at dielectric–elliptic and dielectric–hyperbolic media interfaces

We comparatively investigate Dyakonov surface waves (DSWs) traveling along the plane interface between a dielectric isotropic medium and a lossless anisotropic uniaxial medium with the optic axis (OA) parallel to the interface, when the principal permittivities of the uniaxial medium are both positive (elliptic medium) and of opposite signs (hyperbolic medium). New insights concerning the DSWs are given by analyzing the behavior of the Poynting vector (PV) components. Thus, singularity points at which the PV of the DSW vanishes can exist at the dielectric–elliptic media interface. The range of angles with respect to the OA, which is determined both for the wave vector and the respective PV, can be larger for the DSWs at the dielectric–hyperbolic media interface. Extremely high values of the wave vector and the PV components of the DSWs can be attained at the dielectric–hyperbolic media interface.

Analysis of Dyakonov surface waves existing at the interface of an isotropic medium and a conductor-backed uniaxial slab.

In this paper, Dyakonov surface waves (Dyakonov SWs) existing at the interface between a semi-infinite isotropic medium and a conductor-backed uniaxial slab are analyzed with the help of an exponential-matrix method. The boundary conditions at the interface are formulated using eigenvalues and eigenvectors of two partnering media. Based on this, the existence region of Dyakonov SWs is formulated and proven to be highly dependent on the thickness of the uniaxial slab. Some relevant characteristics of the propagating Dyakonov SWs, such as the distribution of the propagation constant, and the electric- and magnetic-field distributions, are introduced and investigated. In addition, this method can be applied to analyze other finite thickness structures.

Lossless directional guiding of light in dielectric nanosheets using Dyakonov surface waves.

Guiding light at the nanoscale is usually accomplished using surface plasmons. However, plasmons propagating at the surface of a metal sustain propagation losses. A different type of surface excitation is the Dyakonov surface wave. These waves, which exist in lossless media, were predicted more than two decades ago but observed only recently. Dyakonov surface waves exist when at least one of the two media forming the surface exhibits a suitable anisotropy of refractive indexes. Although propagating only within a narrow range of directions, these waves can be used to create modes supported by ultrathin films that confine light efficiently within film thicknesses well below the cutoff thickness required in standard waveguides. Here, we show that 10 nm and 20 nm dielectric nanosheets of aluminium oxide clad between an anisotropic crystal (lithium triborate) and different liquids support Dyakonov-like modes. The direction of light propagation can be controlled by modulating the refractive index of the cladding. The possibility of guiding light in nanometre-thick films with no losses and high directionality makes Dyakonov wave modes attractive for planar photonic devices in schemes similar to those currently employing long-range plasmons.

Coupling plasmons and dyakonons

We study the coupling of plasmons and Dyakonov surface waves propagating at the interfaces between isotropic-birefringent-metal layered structures. Efficient coupling is shown to occur with a proper choice of the crystal birefringence, the refractive index of the isotropic medium, and the light propagation direction relative to the crystal optical axis. In the case of low-loss metals, coupling efficiencies as high as 90% are predicted to be possible.

Dyakonov surface wave resonant transmission

The role of Dyakonov surface waves in the transmission through structures composed of birefringent media is theoretically explored. In the case of structures using prisms, unexpected high transmission above the critical angle due to resonant excitation of Dyakonov surface waves is predicted. This transmission is produced only when TE polarized incident wave reaches the interface supporting the surface waves within a narrow interval of angles, for both the angle of incidence and the angle with respect to the optic axis of the birefringent media. As a result, over 90% transmission for a single and isolated peak confined in the two transversal directions, with hybrid TE and TM polarization, can be obtained.

Dyakonov Surface Waves

Dyakonov Surface Waves

Observation of Dyakonov Surface Waves

We report the first experimental observation of Dyakonov surface waves existing at the interface of transparent anisotropic crystals. A Otto-Kretchmann configuration was used to excite the surface waves at the interface between a potassium titanyl phosphate biaxial crystal and an index-matching liquid fulfilling the conditions at which the waves exist. The signature of surface wave excitation was obtained by using enhanced polarization-conversion reflectance phenomena. We measured the cutoff propagation angles for different index-matching liquids, confirming the high sensitivity of the propagation conditions with the properties of the supporting interface.

On widening the angular existence domain for Dyakonov surface waves using the Pockels effect

AbstractThe propagation of Dyakonov surface waves (DSWs) at the planar interface between an isotropic material and a linear electro‐optic birefringent material can be dynamically controlled using the Pockels effect. The range of directions for DSW propagation has been previously found to be rather narrow. By careful choice of various parameters, this range of directions can be increased by more than an order of magnitude. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2360–2362, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23698

Dyakonov Surface Waves: A Review

The interface of two semi-infinite media, where at least one of them is a birefringent crystal, supports a special type of surface wave that was predicted theoretically by D'yakonov in 1988. Since then, the properties of such waves, which exist in transparent media only under very special conditions, have been analyzed in different geometries and settings. Nevertheless, they are still awaiting experimental demonstration. The most important advances in this topic are briefly discussed in this review, pointing out aspects that have not been clearly covered by the literature. Finally, the existence of these surface waves in specific material examples is analyzed, discussing the challenge posed by their experimental observation.

Optical Dyakonov surface waves at magnetic interfaces

We address the existence and properties of lossless surface waves that form at interfaces between magnetic and birefringent media. We show that the angular domain of existence of Dyakonov surface waves for magnetic interfaces is significantly larger than that for nonmagnetic ones. Our results have important implications for the experimental generation of surface waves and for their potential applications based on guided-to-leaky transitions.

Dyakonov Surface Waves in Photonic Metamaterials

We show that suitable photonic metamaterial structures can support lossless surface waves of the form envisaged by Dyakonov. The idea we put forward is based on the birefringent properties of photonic crystals in the long-wavelength limit, and uses the metamaterial anisotropy of the structures to meet the resonance conditions at which Dyakonov surface waves exist. Implementation of this concept can lead to the first experimental observation of Dyakonov waves, and might open the door to the realization of widely tunable sensing devices based on the unique properties of such waves.