Interaction of Bessel Light Beams with Epsilon-near-zero Metamaterials

The article explores possibilities and conditions of generation of a new type of diffraction-free needle-like field Bessel plasmon polaritons (BPPs) with super narrow cone angle in an epsilon-near-zero metamaterial, surrounded by semi-infinite dielectric media. Correct analytical expressions are obtained and analyzed in detail for the electric and magnetic fields of BPPs formed inside and outside the metamateral slab

Effect of Curing Profile on Kaolin-based Geopolymers

AbstractDepending on the processing conditions, geopolymers can exhibit a wide variety of properties and characteristics. Curing profile serves as a crucial parameter in synthesis of geopolymers. In this paper, the influence of curing temperature and curing time on the properties of kaolin-based geopolymer was studied. The samples were separated into several curing conditions; including curing at ambient temperature, 40°C, 60°C, 80°C and 100°C for 1 day, and up to 3 days. The compressive strength and SEM analysis of geopolymer products were evaluated. Results showed that curing condition has a significant effect on the mechanical properties of kaolin-based geopolymer. Generally, curing at ambient temperature was not feasible, while increase in temperature favored the strength development. In addition, prolonged curing time improved the geopolymerization process, and led to higher strength gain. However, curing at high temperature for a long period of time caused failure of the sample at a later age

Investigation of surface roughness influence on hyperbolic metamaterial performance

The main goal of this work was to introduce simple model of surface roughness which does not involve objects with complicated shapes and could help to reduce computational costs. We described and proved numerically that the influence of surface roughness at the interfaces in metal-dielectric composite materials could be described by proper selection of refractive index of dielectric layers. Our calculations show that this model works for roughness with RMS value about 1 nm and below

Far-field flat lens based on multilayered metal- dielectric structure

The detailed investigation has been made of the lens effect in plane multilayered metal-dielectric structures (Ag-TiO2). The optical scheme of the lens has been studied with the radiation focusing in free space. The transfer function is calculated, where the phase profile determines definitely the possibility of focusing. The condition for far-field image formation is found using a flat lens. This condition is used for a numerical simulation of several lens designs with a various number of metal layers. It is found that considered flat lenses have close to limiting angular aperture and therefore the subwavelength resolution. It is established that at increase of a number of metal layers the object and image distances grow

Sintered and glazed glass-ceramics from natural and waste raw materials

Monolithic sintered glass-ceramics and porous glass-ceramic components were produced from natural raw materials together with industrial waste. The waste, including fly ash from thermal power plants and metallurgical slags, either was mixed with natural raw materials (e.g., clay and silica sand) and vitrified or was directly sintered, after dry pressing at 40 MPa. Fine powders of waste-derived glasses were also converted into sinter-crystallized glass-ceramics, after dry pressing at 40 MPa and subjection of the pressed powders to controlled heating cycles, producing dense components with bending strength as high as ~80 MPa. The two types of waste-derived materials, namely, ceramic tiles from direct sintering and sinter-crystallized glass-ceramics, were combined to obtain double-layered glass-ceramics. These featured a dense wear-resistant coating on a porous substrate and possessed mechanical properties that make them suitable, for example, as structural lightweight panels in building facades

Designing of PVA/Rose Bengal long-pass optical window applications

Poly(vinyl alcohol) (PVA)/Rose Bengal (RB) composite films were prepared by casting technique form aqueous solutions doped with different dye concentrations. The effect of dye concentration on the structure, spectroscopic and optical properties was characterized by X-ray diffraction, optical absorption and fluorescence spectroscopy. The optical limiting properties of PVA/RB films were measured using He-Ne laser beam at 632.8 nm wavelength and showed the best optical limiting behavior at high dye concentrations. The results were interpreted on the basis of hydrogen bonding between hydroxyl groups in PVA and the carbonyl group of face-to face stacked H-aggregates of RB molecules which was evident by all the characterization techniques. Furthermore, PVA/10 wt% RB film showed excellent optical cut-off properties in the spectral range (600–1400 nm) with a high transmission value (Σ 84%) which is a promising result for the long-pass optical filters and protective window applications. Keywords: PVA, Rose Bengal, H-aggregates, Optical limiting, Long-pass filter

Design of Rose Bengal/FTO optical thin film system as a novel nonlinear media for infrared blocking windows

Rose Bengal (RB) is a new organic semiconductor with the highly stable layer, was deposited on highly cleaned conductive glass substrate known as (FTO glass) with different thickness in the range from 80 to 292 nm. XRD showed an entirely amorphous structure of the studied film thicknesses. The observed peaks are the indexed peaks for FTO layer. Spectrophotometric data as transmittance, reflectance, and absorbance were used for the analysis the optical constant of RB/FTO optical thin film system. Refractive index was calculated using Fresnel’s equation with the aid of reflectance and absorption index. The dielectric constant, dielectric loss and dissipation factor were discussed and analyzed according to the applied optical theories. Nonlinear parameters such as third order nonlinear optical susceptibility and the nonlinear refractive index were calculated based on the linear refractive index of the applications of this material in nonlinear media. The results showed that Rose Bengal is a proving material for wide scale optoelectronic applications such as infrared blocking windows. Keywords: Rose Bengal, Dielectric parameters, Linear/nonlinear optics, Dye/FTO, IR blocking window

Honeycomb polymer films with silver nanoparticles

Employing self-organization technique ordered composite materials with honeycomb-structured geometry containing silver nanoparticles on the surface of polymer matrix were fabricated. By annealing initial honeycomb composite structures thin ordered films of silver nanoparticles were formed. The simulation of optical properties of the obtained structures was carried out and compared to measured spectra

White sintered glass-ceramic tiles with improved thermal insulation properties for building applications

none6siIn order to provide a thermal barrier in an arid environment, highly reflective coatings were deposited on porous substrates made of natural raw materials from Saudi Arabia. Although highly reflective coatings inhibit heat absorption from the incoming sunlight, the body of conventional ceramic tiles warms up to environmental temperature through conduction, convection and radiation. A strategy to reduce the penetration of this heat into the building is to use a highly porous substrate, which reduces the thermal conductivity of the tile, coupled with a highly reflective glaze. The approach leads to the concept of "cool" tiles, aimed at improving the thermal efficiency of buildings. The present paper provides a first example, based on layered wollastonite-hardystonite glass-ceramics developed by double pressing of glass powders and additives followed by sinter-crystallization.noneMarangoni, M.; Nait-Ali, B.; Smith, D.S.; Binhussain, M.; Colombo, P.; Bernardo, EMarangoni, Mauro; Nait Ali, B.; Smith, D. S.; Binhussain, M.; Colombo, Paolo; Bernardo, Enric