Experimental study of nonlinear absorption in hyperbolic metamaterials based on ordered arrays of nanorods

Nanophotonics is a rapidly developing branch of physics that studies light interaction with nanoscaled objects such as metamaterials. Hyperbolic metamaterials (HMMs) based on ordered arrays of metal nanorods embedded in a dielectric matrix are of great interest due to their nontrivial optical properties and abilities to control over the parameters of light. In this article, we present the results of nonlinear absorbtion measurements in HMMs based on ordered arrays of silver nanorods. The main finding consists in the spectral vicinity of Epsilon-Near-Zero and Epsilon-Near-Pole features.

Effect of Phase Transformations of a Metal Component on the Magneto-Optical Properties of Thin-Films Nanocomposites (CoFeZr)x (MgF2)100-x

The results of complex studies of structural-phase transformations and magneto-optical properties of nanocomposites (CoFeZr)x (MgF2)100-x depending on the metal alloy content in the dielectric matrix are presented. Nanocomposites were deposited by ion-beam sputtering onto glass and glass-ceramic substrate. By studying the spectral and field dependences of the transversal Kerr effect (TKE), it was found that the transition of nanocomposites from superparamagnetic to the ferromagnetic state occurs in the region of xfm~30 at%, that corresponds to the onset the formation of ferromagnetic nanocrystals CoFeZr with hexagonal syngony in amorphous dielectric matrix of MgF2. With an increase of concentrations of the metal alloy for x > xfm, the features associated with structural transitions in magnetic granules are revealed in the TKE spectra. Comparison of the spectral and concentration dependences of TKE for nanocomposites on the glass and glass-ceramics substrates showed that the strongest differences occur in the region of the phase structural transition of CoFeZr nanocrystals from a hexagonal to a body-centered cubic structure at x = 38 at.% on the glass substrates and at x = 46 at.% on glass-ceramics substrates, due to different diffusion rates and different size of metal nanocrystals on amorphous glass substrates and more rough polycrystalline glass-ceramics substrates.

Controlling photonic spin Hall effect by a symmetric hyperbolic metamaterial waveguide

We investigate the photonic spin Hall effect (PSHE) in a symmetrical hyperbolic metamaterial (HMM) waveguide, which is constructed as an HMM/metal/HMM sandwich structure. We consider both type {\uppercase\expandafter{\romannumeral 1}} and type {\uppercase\expandafter{\romannumeral 2}} HMM in the study. We confirm that the structure of alternating sub-wavelength of plasma and dielectric or the structure of embedding plasma into a host dielectric matrix can display effective dielectric, effective metal, type {\uppercase\expandafter{\romannumeral 1}} and {\uppercase\expandafter{\romannumeral 2}} HMM under different wavelength ranges and different plasma fill fraction. This enable us to simultaneously realize type {\uppercase\expandafter{\romannumeral 1}} and type {\uppercase\expandafter{\romannumeral 2}} HMM. We show that the reflectivity ration $\vert r_{s}/r_{p} \vert$, directly related to transverse shifts generated by PSHE, greatly depends on the type and the thickness of HMM. Moreover, we find that the horizontal PSHE shifts are enhanced several times, especially in type {\uppercase\expandafter{\romannumeral 1}} structure; while the vertical PSHE shifts are significantly suppressed in both type {\uppercase\expandafter{\romannumeral 1}} and {\uppercase\expandafter{\romannumeral 2}} structure. By making the effect of metal type and thickness analysis, we further show that the impacts of these two factors on PSHE shifts are mainly subject to HMM thickness.

Эффективная диэлектрическая проницаемость анизотропного композита из сфероидных частиц в диэлектрической матрице

The concentration dependences of the effective permittivity of an anisotropic composite containing co-directional particles in the form of oblate or elongated ellipsoids of rotation – spheroids – in the dielectric matrix are obtained. The calculation is made by the numerical solution of a system of coupled quadratic and integral equations obtained by a strict modification of the quasi-static Bruggeman theory. It is shown that the traditional (simplified) modification of the Bruggeman theory, widely used for calculating anisotropic composites, gives errors of different signs for the longitudinal and transverse polarization of electromagnetic waves relative to the axis of spheroids. In this case, the dependences of errors on the concentration of particles are non-monotonic, and the extremes observed on them can exceed 100%. Moreover, the position and magnitude of the extremes strongly depend on the ellipticity of the particles, as well as on the contrast of their permittivity with the matrix.

Enhanced piezocapacitive response in zinc oxide tetrapod–poly(dimethylsiloxane) composite dielectric layer for flexible and ultrasensitive pressure sensor

Zinc oxide tetrapod is introduced for the first time within a poly(dimethylsiloxane) dielectric matrix for the formation of ultrasensitive piezocapacitive pressure sensors.

Large photocurrent density enhancement assisted by non-absorbing spherical dielectric nanoparticles in a GaAs layer

Herein, we report a theoretical investigation of large photocurrent density enhancement in a GaAs absorber layer due to non-absorbing spherical dielectric (SiO2) nanoparticles-based antireflection coating. The nanoparticles are embedded in a dielectric matrix (SiN) which improves the antireflection property of SiN ($$\lambda /4$$ λ / 4 coating) and let to pass more photons into the GaAs layer. The improvement is noticed omnidirectional and the highest is more than 100% at 85° angle of incidence with the nanoparticles’ surface filling density of 70%. Sunrise to sunset calculation of normalized photocurrent density over the course of a year have also shown improvements in the nanoparticles’ case.