查看更多>>摘要：? 2022 Elsevier GmbHIn this paper, we describe the design, development and characterization of a compact polarimeter. It works on the technique of rotating quarter wave plate to measure the full Stokes vector state of the incident light. The device integrates low cost commercial off-the-shelf components into a single block which eliminates the need of re-alignment and leads to a better precision and accuracy. The process of performing the intensity measurement and calculation of the polarization state has been fully automated using a microcontroller and a single-board computer i.e. Raspberry Pi. The total measurement time of the polarimeter is around 150 ms. The measurement accuracy and precision of the instrument are 0.5 degree and 0.025 degree respectively.
查看更多>>摘要：? 2022 Elsevier GmbHVariation of correlated colour temperature (Tc) of tuneable LED lamps are thought to have a significant effect on red-yellow and blue colour shades, compared to the green one. The phenomenon is expected to be better explained by observing lightness, hue, and chroma (L*C*h°). However, attempts to map the impact of Tc variation on the shift in colour sample appearance are relatively scarce. Therefore, this study aims to map the relation of Tc variation of a tuneable LED lamp with respect to shift in appearance of theoretical colour samples, using L*C*h° parameters in the CIELAB colour space, and to determine their sensitivity. Interaction between SPD of the tuneable LED lamp and ρ(λ) of each colour sample is observed. Analysis is conducted for 210 colour samples derived from the Burns ρ(λ) model. In most cases, as Tc increases, the colour difference tends to become closer to the reference D65. Relation that can be best explained with regression model is the one between the sensitivity of ΔL* and the h° values. The proposed prediction method of colour samples chromaticity under tuneable LED lamps can therefore be implemented in interior lighting scenes with coloured objects and surfaces.
查看更多>>摘要：? 2022 The AuthorsSpectral and nonlinear optical properties of the new tricarbocyanine dyes, derivatives of the benzo[cd]indole, which absorb efficiently in the region 1.05–1.08 μm, have been investigated. Based on these compounds, the liquid (ethanol solutions) and polymer (in a form of triplexes, where dye-doped polyurethane films are placed between two optical glass substrates) passive Q-switches for the neodymium lasers have been developed. The modulation depth of 100% at the generation of the ultrashort pulse (USP) trains has been obtained. The high-stable regime of passive mode-locking has been realized; it is characterized with the 100% probability appearance of a single pulse in an axial period with average durability 25–30 ps and energy 1–2 mJ, depending on the dye structure. Advantages of the new Q-switches over the corresponding analogues, based on organic dyes, nanotubes, graphene, inorganic semiconductors and mirrors (SESAM), LiF:F2ˉ and Cr4+:YAG, have been demonstrated.
查看更多>>摘要：? 2022 Elsevier GmbHWide bandgap NiO is vital for the photodegradation of organic molecules like dyes, bacteria, viruses, and for water decontamination. Calcium oxide is another efficient catalyst due to the presence of greater active sites. In this study, CaO molecules were incorporated into the NiO matrix by calcium doping. It was assumed that the incorporation of CaO would enhance the photocatalytic performance of NiO. Pure and calcium substituted NiO samples were prepared by simple co-precipitation method. The samples were characterized by X-ray diffractometer, SEM, UV–visible, and FTIR spectrometer. XRD profiles show the successful formation of NiO and Ca-doped NiO cubic nano crystallites. UV–visible spectroscopy revealed a shift in absorbance peaks toward longer wavelengths and decreased bandgap in Ca-doped samples. Photodegradation study revealed superior photocatalytic performance of doped samples under similar conditions. The improved photocatalytic performance of Ca-doped NiO is attributed to greater active sites and decreased bandgap due to the formation of new energy levels by the impurity addition. This study demonstrates that calcium doping in nickel oxide has enhanced the photodegradation efficiency from 45 % to 98.15 %.
查看更多>>摘要：? 2022 Elsevier GmbHIn this work we propose a formulation for the treatment of quantized states of light in photon-matter interaction. It is built in the multidimensional Hilbert space to describe the orbital angular momentum states, in such that probabilities naturally arise in a relativistic setting. Our findings indicate that the classical-relativistic variability of the probabilities can describe the quantized states of light, with the state variable being the variation of the photon angular momentum. It was verified that the probability to find a specific quantized state of light at angular incidence can be treated by relativistic probabilities. Interestingly, our results indicate that, when both states have equal odds, there is a synchronization between source and observer. We found that the relativistic effect in the perspective of the source referential is able to change the odds of an event occurring, dilating and contracting the probabilities of finding a quantized state of light at angular incidence.
查看更多>>摘要：? 2022 Elsevier GmbHThe paper presents the results of a novel 3-D shared aperture 3 × 3 matrix antenna-array for 26 GHz band 5 G wireless networks. Radiation elements constituting the array are hexagonal-shaped patches that are elevated above the common dielectric substrate by 3.35 mm and excited through a metallic rod of 0.4 mm diameter. The rod protrudes through the substrate of 0.8 mm thickness. It is shown that by isolating each radiating element in the array with a wall suppresses unwanted electromagnetic (EM) wave interactions, resulting in improvement in the antenna's impedance matching and radiation characteristics. Moreover, the results show that by embedding hexagonal-shaped slots in the patches improve the antenna's gain and radiation efficiency performance. The subwavelength length slots in the patches essentially transform the radiating elements to exhibit metasurface characteristics when the array is illuminated by EM-waves. The proposed array structure has an average gain and radiation efficiency of 20 dBi and 93%, respectively, across 24.0–28.4 GHz. The isolation between its radiation elements is greater than 22 dB. Compared to the unslotted array the improvement in isolation between radiating elements is greater than 11 dB, and the gain and efficiency are better than 10.5 dBi, and 25%, respectively. The compact array has a fractional bandwidth of 16% and a form factor of 20×20×3.35 mm3.
查看更多>>摘要：? 2022 Elsevier GmbHObjective: In this article, we theoretically simulated a silicon core-based photonics crystal fiber combined with the Au/graphene coating thin-film to surround the fiber-air-holes with a plasmonic active medium for sensing NH3 gas concentrations. Methods: By means of our previous research experiences and the related theory, the complex refractive index of graphene under different concentrations of NH3 exposing was analyzed and calculated by using the finite element method. Result: The sensing average sensitivity of 0.0269 nm/ppm for the proposed NH3-gas sensor was theoretically predicted for the concentration of NH3 in the range from 1 ppm to 1000 ppm. In addition, the proposed photonics crystal fiber sensor can be extended into the other field applications, such as medical diagnostics, bio-chemical detection etc.
查看更多>>摘要：? 2022 Elsevier GmbHObjective: This work aimed to produce Ag@TiO2 nanoparticles/PS ultra-high sensitivity for humidity by laser ablation. Methods: we combine Ag/TiO2 NPs of 59.93 nm with porous silicon (PS) to create a nanocomposite system. On an n-type silicon wafer, the structural, morphological, and optical properties of a silicon bulk and PS layer are detailed in depth. Results: The PL regarding the sample PS and Ag/TiO2 NPs is measured in air at various relative humidity (RH) levels. PS's PL band is associated with quantum confinement; PL for the Ag/TiO2 system has a broad peak. Even though the decline in intensity could be attributed to Ag/TiO2 absorption regarding the excitation and emission radiations, this shows the peak from PS. In the case when RH levels rise, the PL of the PS and Ag/TiO2/PS humidity sensors alter. The intensity of the PL lessens. This effect may be described as capillary condensation of water vapor within PS pores.
查看更多>>摘要：? 2022 Elsevier GmbHSeveral studies have been carried out with several materials on the removal of methylene blue from water. Well-known bioactive glass 46S5.2 was prepared by complete replacement of the silicate partner with boron oxide via a two-step crystallization process, in particular its glass-ceramic derivative. The characterization techniques for ceramic sample were performed such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray (EDX). Transmission electron microscope (TEM) was employed to ensure that silver addition reaches to the nanoscale. UV/Vis. optical absorption spectroscopy was utilized in the retracing process of methylene blue adsorption from its contaminated water. The antimicrobial activity of the prepared sample was also studied extensively. Also for the prepared glass-ceramic samples, the reusability test was carried out to ensure that they could be used more than once in water treatment applications.
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