Fiber Bragg gratings (FBGs) technology has demonstrated its suitability for many applications in recent fiber technologies. Sensing application is one of the main applications of FBGs. In this work, we present a comprehensive investigation for using apodized FBGs in sensing applications. Different evaluation parameters such as, reflectivity, sidelobes, and full-width-half-maximum (FWHM) are tested in order to determine the most proper apodization profile for sensors. According to our study, the Blackman apodization gives the best profile that can be used in sensing applications. The reflectivity of Blackman apodization is nearly unity with minimum sidelobes level, -60.3 dB, and narrow FWHM. The length of Blackman apodized FBG is 0.33 cm and Δn = 14.4 × 10 ^□4 and maximum reflectivity is 99.44%.

In this paper, a randomly distributed plasmonic aluminum nanoparticle array is introduced on the top surface of conventional GaAs thin-film solar cells to improve sunlight harvesting. The performance of such photovoltaic structures is determined through monitoring the modification of its absorbance due to changing its structural parameters. A single Al nanoparticle array is integrated over the antireflective layer to boost the absorption spectra in both visible and near-infra-red regimes. Furthermore, the planar density of the plasmonic layer is presented as a crucial parameter in studying and investigating the performance of the solar cells. Then, we have introduced a double Al nanoparticle array as an imperfection from the regular uniform single array as it has different size particles and various spatial distributions. The comparison of performances was established using the enhancement percentage in the absorption. The findings illustrate that the structural parameters of the reported solar cell, especially the planar density of the plasmonic layer, have significant impacts on tuning solar energy harvesting. Additionally, increasing the plasmonic planar density enhances the absorption in the visible region. On the other hand, the absorption in the near-infrared regime becomes worse, and vice versa.

This paper investigates the absorption spectra of a plasmonic metamaterial absorber in the visible and near-infrared regimes by utilizing a metal-dielectric-metal (MDM) functional stack. A periodic metal-dielectric cap is introduced on top of a metallic substrate to excite surface plasmon modes. The shape of this cap and the glass coating modifies the absorbance bandwidth. Although the circular cap exhibits less broadening in the absorbance than the square one, the circular cap’s glass coating boosts the bandwidth’s expansion in the near-infrared region to about 1.65 µm. In the visible and near-infrared regimes, absorption bandwidth and spectral ratio can be tailored by modifying four distinct structural parameters. The finding shows that one can achieve an ultra-broad bandwidth that extends from 0.3 µm to 1.65 µm at 90% absorbance. The thickness of the top titanium layer, the silicon dioxide spacer thickness, the Ti-SiO₂ cap diameter, and the sliver substrate pitch are selected to be 20 nm, 60 nm, 215 nm, and 235 nm, respectively. Furthermore, the influence of using various metals on absorption spectra has been explored in the visible and near-infrared regimes. The d metals considered for the top layer are titanium, nickel, chromium, silver, copper, gold, aluminum, and gold.

Dilute magnetic semiconductor films (GaMnN) are highly resistive, making transport measurements difficult to achieve. However, when GaMnN films are sandwiched between $p$ -type doped $(\mathrm{Al}\mathrm{Ga}\mathrm{N}∕\mathrm{Ga}\mathrm{N})$ strained-layer superlattices, holes from the superlattice interact with the ${\mathrm{Mn}}^{3+∕2+}$ ions and transport measurements were realized. The authors have found also that the ferromagnetic properties of GaMnN critically depend on the level of $p$ -type doping in the superlattice. They report anomalous Hall effect measurements in this $(\mathrm{Al}\mathrm{Ga}\mathrm{N}∕\mathrm{Ga}\mathrm{N}):\mathrm{Mg}∕\left(\mathrm{Ga}\mathrm{Mn}\mathrm{N}\right)$ multilayered structure. The current results also demonstrate the role of carriers, especially holes, in mediating the ferromagnetic properties of GaMnN dilute magnetic semiconductor films.