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Abstract With the development of science and technology, phononic crystals can be fabricated at nanoscale. The advancement yields significant applications in thermo-electric, acousto-optical and electron-phonon devices. At nanoscale, the surface heterogeneity of structures is a result of the differences between the arrangement and environment of the surface atoms and those of their counterparts in the body. This characteristic plays an important role in determining the mechanical properties of the structures. The effects of surface heterogeneity on band structures of the phononic crystals at nanoscale are studied in this paper. We also investigate the topological properties of phononic nanobeams through theoretical and numerical approaches. The topological edge mode, which is affected by the surface heterogeneity, is observed. Particularly, a theoretical method based on the plane wave expansion method is proposed to conveniently calculate the Zak phase, which is an important constant describing the topological properties. The numerical results show that surface heterogeneity mainly influences the response frequency for the dispersion relations and the topological behaviors in the phononic nanobeam. The study may be beneficial for the understanding of the size-dependent behaviors of phononic crystals at nanoscale and for the design of nanodevices based on the dispersion and topological properties of phononic crystals. [ABSTRACT FROM AUTHOR]

Spin waves propagation in 1D magnonic crystals is investigated theoretically. Mathematical model based on plane wave expansion method is applied to different types of magnonic crystals, namely bi-component magnonic crystal with symmetric/asymmetric boundaries and ferromagnetic film with periodically corrugated top surface. It is shown that edge modes in magnonic crystals may exhibit nonreciprocal behaviour at much lower frequencies than in homogeneous films. [ABSTRACT FROM AUTHOR]

• The gold nanostructure was designed to have two edge plasmon modes whose wavelengths are independently tunable. • Wavelength-tunable range was from approximately 800 to 1800 nm. • The optimal design for application using 785 and 1064 nm laser was successfully suggested. • The electric field enhancement of optimal design reached 1.5 × 104 and 7.7 × 103 for 785 and 1064 nm. Metal nanostructures have attracted attention because of their unique optical characteristics derived from localized surface plasmon resonance. In this study, gold nanoholes with edge structures were designed and characterized to possess two plasmon bands at different wavelengths. These bands were assigned to the plasmon modes that generated a concentrated electric field at the tip of the individual edge structures. Furthermore, wavelengths of these bands were independently tuned from the visible to near-infrared wavelengths with shape and size of the gold nanoholes and edge structures as variables. To demonstrate wavelength tuning, a gold nanostructure with edge plasmon bands at wavelengths of approximately 785 and 1064 nm (typical laser wavelengths for surface-enhanced Raman scattering and optical tweezers, respectively) was successfully obtained via optical simulation. The results indicate that the structure designed in this study provides a guideline for the design of optical devices with efficient multiple optical functions. [ABSTRACT FROM AUTHOR]

In this paper, the edge mode vibration is studied with three different methods: the reciprocal work method, already used by Torvik [J. Acoust. Soc. Am. 41 (1967) 346] to model this phenomenon, the S-parameter method and a finite element model that are applied for the first time to the study of the edge resonance. Moreover, laser probe measurements of the edge mode have also been performed and compared to the numerical predictions. The good agreement between the numerical predictions and the experimental data allows full understanding of the resonant phenomenon. The edge resonance is linked to the strong increase in amplitude of two complex Lamb waves, and the edge mode is proved to radiate into the plate as the first symmetrical Lamb mode S0. Displacements at the edge and away from the edge have been computed and measured to evaluate the spatial and temporal behaviour of the edge mode. The dependence of the edge resonance frequency and amplitude on the Poisson coefficient has also been studied. [Copyright &y& Elsevier]

Some new properties of optical diodes were investigated, as well as compared with the known ones for the following three systems: 1) an isotropic magnetoactive layer, 2) a magnetophotonic crystal layer, and 3) a photonic crystal with a helical structure, assuming that these systems are in an external magnetic field and have giant parameters of magneto-optical activity. It is shown that these systems can be used as broadband ideal optical diodes. At giant values of the magneto-optical activity in the long-wavelength region of the spectrum, there appears a new photonic band gap (PBG) for helically structured photonic crystals. Accordingly, two PBGs and a transparent window between them appear in the whole spectral region. When magneto-optical activity parameter increases, this new (the second) PBG occupies the entire spectrum. Furthermore, the light localization at the edge modes is investigated. It is shown that an unusually strong light localization takes place at some modes. The trapped total light energy and the energy density peculiarities are investigated, too. Image 1 • Diode properties of isotropic magneto-active layer in the external magnetic field was investigated. • Diode properties of magnetophotonic crystal layer was investigated. • Diode properties of chiral structured photonic crystal being in external magnetic field was investigated. • Light localization peculiarities was investigated. [ABSTRACT FROM AUTHOR]