Results in Optics最新文献

We review the analytical expressions for the complex Poynting’s vector in the case of arbitrary plane-waves in a lossy isotropic medium. We demonstrate how these expressions can be used to recover the optical absorption power density $Q$, considering the divergence of the time-averaged Poynting vector. This quantity, proportional to the imaginary part of the dielectric function and the field intensity, i.e. $Q\propto {\left|E\right|}^2\varepsilon$”, is usually established for harmonic fields, using the Poynting’s identity. The derivation from the complex Poynting vector expression is more direct for TE-polarized homogeneous waves, but the derivation encompasses the other cases like inhomogeneous TM plane waves. As an application, the optical absorption profile $Q\left(x\right)$ within 1D multilayers is detailed using matrix transfer method for both TE and TM plane waves, including the evanescent case.

The structural, magnetic, optical, and adhesion properties of Cobalt-Iron-Dysprosium (CoFeDy) films were investigated in this study. Glass substrates were coated with a Co₆₀Fe₂₀Dy₂₀ alloy via sputtering, with a thickness ranging from 10 nm to 50 nm. Subsequently, the films underwent annealing at temperatures of 100 °C, 200 °C, and 300 °C for one hour. X-ray diffraction (XRD) analysis confirmed the amorphous nature of the deposited CoFeDy films under four distinct conditions. Notably, a thickness-dependent increase in low-frequency alternate-current magnetic susceptibility (χ_ac) was observed. After annealing at 300 °C, CoFeDy films exhibited the highest χ_ac compared to other temperatures. Surface roughness exhibited a decreasing trend with rising annealing temperature, as observed through atomic force microscopy (AFM) experiments. The maximum surface energy of CoFeDy films was achieved at a thickness of 50 nm following annealing at 300 °C. Higher surface energy was indicative of stronger adhesion efficiency. Furthermore, lower resistance and sheet resistance values were obtained through annealing at higher temperatures, suggesting that increasing thickness and reducing electron transport barriers enhanced electron conductivity. As film thickness increased, transmittance decreased due to the thickness effect, suppressing the photon signal. Consequently, rougher surfaces were associated with improved performance in magnetism, electrical adhesion, and optics, attributed to reduced domain pinning, enhanced carrier conductivity, and minimized light scattering.

In this work, Li-doped ZnO nanocrystals (LZO) were synthesized via the sol–gel method. The concentration of zinc acetate has been set at 2 M in order to prepare the highly concentrated Li-doped ZnO sol. The generated LZO sol’s optical characteristics were assessed using UV–visible absorption and photoluminescence spectroscopy, while the ZnO nanopowders’ lithium doping process was assessed using XRD and Raman spectroscopy. The experimental findings indicate that the concentration of Li⁺ ions in the synthesized zinc oxide nanocrystals has reached the maximum solid solubility limit. The inclusion of Li⁺ ions results in a reduction in the size of ZnO nanocrystals, accompanied by a notable increase in violet-blue emission, distinguishing them from other materials reported in the literature. As can be found, Li⁺ ions cannot change the type of conductivity in thin ZnO films, and they have n-type conductivity.

This paper presents a thin film coupled Fabry–Perot cavities optical interleaver. The simulation results for the interleaver shows an outstanding performance in accurately selecting the required channels and robustness in the channel profile. The accuracy is achieved by varying the range of the incident angle. Furthermore, the interleaver has a re-configurable incident angle range with fine and coarse angle ranges, which provides a broader range of applications for such an interleaver. Moreover, the proposed approach provides the reconfigurability for the interleaver performance, which is now a reconfigurable thin-film-based device for selecting the odd/even interleaved channels. The channel selection is based on specific angle values for fine and coarse ranges. Such a device will add more flexibility and multi-functionality to the optical system.

The skewness parameter ‘s’ of a skew-cosh-Gaussian (skew-chG) laser beam travelling through collisionless plasma was analytically investigated in the current theoretically study. In this problem, the self-focusing and defocusing of a skew-chG beam in collisionless plasma has been studied successfully by utilising the Akhmanov’s parabolic equation technique under Wentzel-Kramers-Brillouin (WKB) and paraxial approximations. The dielectric function of plasma under consideration here exhibits ponderomotive type nonlinearity. Our primary goal is to understand how the skewness parameter affects the beam-width parameter changes during plasma propagation. It is observed that the skewness parameter ‘s’ is more noticeable at a higher order of skewness ‘n’ of the skew-chG laser beams. With increasing skewness parameter the critical curves shifts downward and the enhanced self-focusing is observed and the rate of defocusing is decreases. It has been found that improved self-focusing in plasma depends on optimising the skewness parameter ‘s’ of the skew-chG laser beam. The results are revealed graphically and discussed.

In this contribution, a simple non-destructive characterization of aging degree of oil-paper insulation materials based on the reflectance is proposed. Samples of cellulose Kraft paper having different thicknesses, were thermally aged in a mineral insulating oil and a synthetic ester with a controlled aging history. The degree of polymerization of the non-aged and aged paper samples was measured according to ASTM D4243 to monitor the cellulose degradation. In addition, the samples were optically analyzed to assess changes in paper’s reflectance. The reflectance spectra of the thermally aged paper samples were statistically analyzed using linear, single variable, and multi-variable analyses by considering eight popular variables. This enables correlating the reflectance to the degree of polymerization and identifying a suitable regression model. Appropriate variable interaction has been performed among which two best-fit models with goodness of fit ≥ 0.9 have been identified. The estimation of the cellulose paper’s DP using the proposed models is reported. The experimental results show that the proposed approach can be used in characterizing aging degree of oil-paper insulation and has the potential to be implemented online as an effective monitoring technique.

This paper presents a detailed study of double perovskite (FA)₂BiCuI₆ based perovskite solar cells(PSC) using different kesterites as hole transport layers (HTL) and titanium-based electron transport layers (ETL). The designed double perovskite PSC utilized ${TiO}_2$ as an ETL, different kesterite materials (CZTSe, CFTS, CBTS, CMTS, CNTS and CZTS) as the HTL, double perovskite material (FA)₂BiCuI₆ as the perovskite absorption layer (PAL), Indium tin oxide (ITO) as top electrode and Au as an anode. The different parameters of architecture (ITO/TiO₂/(FA)₂BiCuI₆/HTL/Au) is improved via the SCAPS-1D simulator by first optimizing thickness and then the defect density of PAL. Energy band matching of the different layers with (FA)₂BiCuI₆ is thoroughly investigated in order to understand its operation. AM 1.5G illumination is used as input light source. To obtain optimum performance of (FA)₂BiCuI₆ based PSC the effects of optical thickness, defect density, temperature, series resistance, and shunt resistance are monitored. Among all the kesterites, CNTS based PSC performed extraordinarily well with PCE of 26.09 %. J_SC 22.64 mA/cm², V_OC 1.38 V, FF 83.33 %, and the variables influencing solar cell performance are clarified by simulations. The findings presented in this work will aid researchers in the production of ecofriendly solar cells with great efficiency.

This paper aims to enhance understanding regarding the impact of the geometrical parameters of the grating on the transmission spectrum of single-mode and multimode fiber Bragg grating sensors and to compare the performance of both sensors for temperature monitoring. Furthermore, we propose a novel design where we combine between phase shifted and tilted grating in MMFBG sensors to further enhance their sensitivity and make them more suited for temperature sensing applications. In this regard, a numerical simulation using the eigenmode expansion (EME) solver of Lumerical software is conducted. Analysis of the obtained results suggests that the multimode Fiber Bragg grating sensor has the potential to be used as a temperature sensor with good sensitivity when it is well designed.

This study explores the impact of CaTiO₃ and LiNbO₃ crystals on the optical and dielectric properties of polyvinylidene fluoride (PVDF) films. Our investigation employs UV–Visible Spectroscopy to characterize the n-π* C-F related electronic transition within the PVDF matrix. We find that CaTiO₃ crystals significantly decrease the composite’s band gap and dielectric properties, enhancing its electronic and optical attributes. Conversely, LiNbO₃ crystals increase the band gap energy. These variations align with observed DC conductivity changes, suggesting novel functionalities for optoelectronic, sensing, and energy storage applications.

In this article, we used modern technologies to teach the topic of nanomaterials and nanotechnologies. One of the main tasks of the development of modern nanotechnologies and nanomaterials is one of the main tasks of the development of nanoscale solid, liquid and gas phase structures and systems.