Plasmonic nano-antennas are widely accepted as suitable platforms for biosensing tasks because Surface Plasmon Resonance (SPR) is very sensitive to changes in its environment. However, recent studies suggest that SPRs may have limited Quality (Q) factors, especially in comparison with their dielectric counterparts. Therefore, this paper attempts to innovate the design of plasmonic nano-antennas to achieve high Q factors through Surface Lattice Resonance (SLR) in the visible frequency band. This resonance is linked with plasmonic nanostructures organized in arrays. The structure consists of a metal-dielectric-metal configuration at the base with metallic nanopillars protruding upward. The nanophotonic device has been investigated for refractometric sensing applications. The maximum Q factor achieved as a result of this work is 245, which has been compared with contemporary plasmonic metasurface Q factors. The simulation framework has been implemented in COMSOL Multiphysics, which employs the Finite Element Method (FEM). Regression analysis has been used to formulate the calibration curve for the sensor. High Q factors provide better selectivity for biosensing applications.

A pulsed reactive magnetron sputtering system with a tungsten target and a gas mixture of argon and oxygen was investigated as a source for the deposition of semiconductor WO3 thin films on soda lime glass substrates and on the glass with transparent conductive SnO2:F (FTO) electrode. The reactive sputtering process was performed in HiPIMS mode with low pulse repetition frequency fp ti 50-100 Hz and short pulse duration in HiPIMS discharge Ton = 100 mu s. The second mode investigated was the mid-frequency (MF) magnetron discharge with pulse frequency fp = 40 kHz and pulse length Ton = 15 mu s. The plasma parameters were investigated for both HiPIMS and MF modes using the planar RF probe operating at the frequency fprobe = 350 kHz and the grid QCM with biased collector electrode. Ion density ni and tail electron temperature (Te) were determined in both pulsed reactive magnetron sputtering discharge modes with time resolution. The maximum value ni ti 5 center dot 1017 m- 3 was found in the reactive HiPIMS mode, and the maximum value ni ti 7 center dot 1016 m-3 was found in the reactive MF (40 kHz) mode. The degree of ionization of sputtered particles in reactive HiPIMS was determined for different values of (QO2) and was found to be in the range of ri ti 0.1-0.3. The deposition rate determined by QCM in reactive HiPIMS was practically independent on (QO2), but in the case of reactive MF, the measured deposition rate decreased significantly with increasing (QO2). The WO3 films deposited in both modes have a predominantly monoclinic crystal structure. The light and dark conductivity and the light/dark conductivity ratio (Ld) were measured under dark conditions and UV light illumination. At higher (QO2), the maximum value of Ld ti 300 was found for MF deposited WO3 and the maximum value of Ld ti 30 was found for HiPIMS deposited WO3. The photoelectrochemical measurement of WO3 deposited on FTO electrodes confirmed the n-type conductivity, and these films functioned as photoanodes in photoelectrochemical cells. MF deposited WO3 films systematically exhibited slightly higher photocurrents than HiPIMS deposited WO3. It was shown that these optimum photocurrents for HiPIMS and MF were found at QO2 ti 80 sccm and could not be improved by further increasing of (QO2).

A metal-dielectric interface has been studied in this paper in the light of wave propagation characteristics. A new analytical result, through a simpler approach for deriving the dispersion equation in plasmonic waveguides, has been reported and visualized. A two-dimensional Transverse Magnetic (TM) wave is theorized and analyzed with respect to its propagation along the boundary of metal and air. Mathematical analysis results in the relationship between the propagation parameter and wavelength of operation. The plots reveal good conformity with the previous studies. For comparison, the propagation characteristics in free space have also been included. To validate the proposed results of this study, Finite Element Analysis (FEA) has been used to visualize the distribution of fields near the metal-dielectric boundary

This paper presents a novel hybrid model employing Artificial Neural Networks (ANN) and Mathematical Morphology (MM) for the effective detection of defects in solar cells. Focusing on issues such as broken corners and black edges caused by environmental factors like broken glass cover, dust, and temperature variations. This study utilizes a hybrid model of ANN and K-Nearest Neighbor (KNN) for temperature prediction. This hybrid approach leverages the strengths of both models, potentially opening up new avenues for improved accuracy in temperature forecasting, which is critical for solar energy applications. The significance lies in the interconnectedness of temperature fluctuations and solar cell efficiency, leading to defects. The proposed model aims to predict temperatures accurately, providing insights into potential solar cell efficiency problems. Subsequently, this work studies the transitions to defect detection using Fuzzy C-Means (FCM) clustering and MM techniques. The hybrid model demonstrates accurate temperature prediction with Mean Absolute Percentage Error (MAPE) values of 0.92%, 0.72%, and 1.3% for average, maximum, and minimum temperatures, respectively. The defect detection process yields a detection accuracy (CR) of 96% and sensitivity of detection (SD) of 89%. This work is validated compared to the literature work done and by using K-fold cross validation technique. The proposed work emphasizes the improvement in defect detection accuracy and the overall quality enhancement of solar cells.

In this article, the 'terahertz gap' has been addressed by designing a novel THz metasurface for potential use in biosensing applications. The metasurface sensor employs surface plasmon resonance (SPR). It operates in the 0-1 THz band. Two sharp reflection dips are provided by the sensor, which serve as indicators of analyte refractive index variations. Geometrical as well as compositional parameters of the biosensor design have been studied to optimize the performance in the targeted frequency band. The sensor design shows compatibility with different metals. The performance of the metasurface with gold, copper, and aluminum has been investigated. The metasurface geometry is decently resilient to fabrication tolerances. The sensor maintains its resonance conditions when the angle of incidence is changed with minor deviations in the spectral response, but the polarization state of the incident terahertz beam clearly disturbs the absorption peak. Therefore, the sensing performance is restricted to a maximum allowable incidence angle of 20. and circularly polarized terahertz beams. The resonance conditions for the metasurface appear around 0.4 and 0.7 THz. Both resonances have been investigated with respect to changes in the analyte refractive index. The chosen refractive index range is 1 to 1.5. The sensor response is calibrated by plotting the resonance frequency versus the refractive index. Least squares regression technique has been used to extract a data model for sensor response. Comparison of the proposed design with contemporary works has been incorporated into the article. The sensor provides sensitivities of 0.1614 and 0.23 THz/RIU. The electromagnetic simulations have been carried out through the finite element method (FEM).

As the limitations of integrated electronics start to appear, it becomes important to look for potential alternatives. Silicon photonics holds a lot of promise in this regard. It cannot only provide superior performance to traditional integrated electronics in many aspects, but also co-exist in harmony with it through the realization of electro-optic devices. The focus of this paper is on Photonic Integrated Circuits (PICs) only. A theoretical understanding of Mach-Zehnder Interferometer (MZI) circuits has been developed. Computational design tools have been employed to model photonic waveguides. The design of optical waveguides has been numerically investigated in MATLAB through the Effective Index Method (EIM). The material properties of silicon and silicon dioxide, used in the simulations, have been presented. The properties include the refractive indices, group refractive indices and effective indices. Waveguide geometrical parameters have been explored and a 500 nm x 220 nm silicon waveguide structure has been finalized for experimental work. The schematics for four MZI optical circuits have been prepared in KLayout. Interoperability of KLayout and Ansys Lumerical Interconnect allows for spectral response to be obtained through simulations. The circuits consist of grating couplers, Y-branch splitters and bidirectional couplers. The input signal is split into two waveguide paths. Both waveguide paths culminate into grating couplers connected to photodetectors. The signals from both the channels have been recorded. The fabrication of the chip has been carried out at Applied Nanotools Inc. through Electron Beam Lithography (EBL). The characterization of the devices has been done at 25oC. A decent conformity can be observed between simulation and experimental results.

Early detection and monitoring of diabetes ensures sound health of humans. With the recent progress in metamaterial-based sensing mechanisms, efforts have been made to introduce flat optical glucose biosensors for diabetes detection. In this paper, a plasmonic blood glucose biosensor has been proposed and analyzed with respect to changing optical parameters of blood due to changing glucose levels. The sensor operates in the terahertz regime.

The pulse length dependence of a reactive high power impulse magnetron sputtering (HiPIMS) discharge with a tungsten cathode in an argon+oxygen gas mixture gas was investigated. The HiPIMS discharge is operated with a variable pulse length of 20-500 mu s. Discharge current measurements, optical emission spectroscopy of neutral Ar, O, and W lines, and energy-resolved ion mass spectrometry are employed. A pronounced dependence of the discharge current on pulse length is noted while the initial discharge voltage is maintained constant. Energy-resolved mass spectrometry shows that the oxygen-to-tungsten (O+/W+) and the tungsten oxide-to-tungsten (WO+/W+) ion ratio decreases with pulse length due to target cleaning. Simulation results employing the SDTrimSP program show the formation of a non-stoichiometric sub-surface compound layer of oxygen which depends on the impinging ion composition and thus on the pulse length.

This paper proposes an optical sensor based on nanoscale metamaterial structures. The design of the sensor has been explored with respect to biosensing applications through numerical modeling and analysis. The sensor comprises silica substrate and diamond nanostructures, both of which represent dielectrics. The sensing principle is based on the detection of ambient refractive index change. As the analyte properties change, the refractive index changes, as well. The refractive index change has been detected by striking electromagnetic waves onto the structure and noting the spectral response. Ultraviolet waves have been utilized for recording spectral responses and evaluating sensor performance. The sensor displays multiple sharp resonance peaks in the reflected beam. By altering the refractive index of the analyte present around the sensor, the peaks can be seen choosing different wavelengths. The resonance peaks have been investigated to observe electric and magnetic field dipoles in the sensor structure. The spectrum peaks have also been studied to understand fabrication tolerances. The sensor displays a linear response, along with a large Quality (Q) factor. The maximum value of the achieved Quality (Q) factor for the proposed sensor is 1229 while operating across the refractive index range of 1.4–1.45. The claim has been supported by comparison with contemporary works on similar platforms. A range of other sensing parameters have also been calculated and benchmarked. Metamaterial-based optical sensors can provide smaller device sizes, faster response times and label-free detection.

Although freshwater is necessary for the well-being of humankind, increasing population growth and limited resources lead to a serious crisis to supply freshwater. Since the Earth is surrounded by seawater, desalination based on electrical power is introduced as a promising technology to provide freshwater. It is well documented that the connection of remote areas that usually do not have access to freshwater into the electricity grid is not affordable and eco-friendly. Hence, the efforts to design and construct high reliability, cost-effective, and ecofriendly stand-alone hybrid renewable energy system in remote areas. In line with this, this paper describes a novel energy management system for the optimized operation of a stand-alone hybrid energy system based on photovoltaic panels, wind turbines, batteries, and diesel generator. For this purpose, a multi-objective optimization problem is formulated by combining three objective functions, i.e., minimum the total life cycle cost as well as environmental impacts on human health and ecosystems and the maximum system reliability that can conflict with each. To solve the multi-objective optimization problem, a division algorithm is proposed that is more flexible and faster compared with conventional algorithms such as genetic algorithm. In order to show the proposed framework, a real case study in Larak Island, Iran, with appropriate solar and wind is considered. The effectiveness of the applied approach compared with optimization results of genetic algorithm and the artificial bee swarm optimization algorithm that was previously used successfully to solve optimization problems related to desalination integrated with the renewable energy system. The optimization is performed based on different diesel fuel price amounts (0.2, 0.5, and 1 $/liter). It is seen that at fuel price set to 0.2 and 0.5 $/liter, the seawater reverses osmosis desalination/photovoltaic/diesel generator/battery is the most cost-effective energy system, and when fuel price is 1 $/liter, the seawater reverses osmosis desalination/photovoltaic/wind turbine/ diesel generator/battery is the most cost-effective hybrid system. While at fuel price set to 0.2, 0.5, and 1 $/liter, the seawater reverse osmosis desalination /photovoltaic/wind turbine/diesel generator/battery is the most ecofriendly. Finally, the results of this study show proposed algorithm is faster and more accurate (100 iterations, 98.36% accuracy) than the genetic algorithm (1000 iterations, 83.03% accuracy) and the artificial bee swarm optimization (300 iterations, 95.49% accuracy).

In this paper, a new plasmonic absorbing metasurface sensor has been proposed to determine glucose concentrations. Surface Plasmon Resonance (SPR) shift has been used as the indicator of glucose concentration. The sensor employs metal-dielectric-metal configuration along with metal nano-cylinders to provide near unity absorption in the near infrared wavelength range (1800- 2200 nm). The absorption frequency shifts when the sensor is surrounded by materials of different refractive indices. The structure has been investigated through Finite Difference Time Domain (FDTD) simulations. The results show reflectance and absorbance peaks with different analyte concentrations. The sensor displays a linear response along with sensitivity and Figure of Merit (FOM) equal to almost 500 nm/RIU and 11.82 RIU-1, respectively. The proposed sensor has potential applications in food and biomedical industries.

Copper tungsten oxide films are deposited with the help of reactive high power impulse magnetron sputtering (HiPIMS) in an argon/oxygen gas mixture. Two magnetrons, one equipped with a tungsten target and the other with a copper target, are employed. The HiPIMS discharge is operated with a repetition frequency of f=100 Hz. Pulse widths of 100 and 20 μs separated by 25 μs are chosen for the tungsten and copper target, respectively. Films deposited on two different glass substrates [soda lime glass and fluorine doped tin oxide (FTO) coated glass] are characterized by energy dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction, Raman spectroscopy, and ellipsometry. Photoelectrochemical activity was investigated by linear voltammetry. The composition and crystal structure of as-deposited and annealed films are found to depend on the deposition conditions. Annealed films deposited on FTO glass are composed of WO3 and CuWO4 or Cu2WO4 crystal phases. Films deposited on soda lime glass are subject to sodium diffusion into the films during annealing and the formation of Na2W2O7 and Na2W4O13 phases.

Tungsten oxide films are deposited with the help of reactive magnetron sputtering in an argon/oxygen gas mixture. Films are deposited on different substrates, in particular, on soda lime glass, fluorine-doped tin oxide coated glass, silicon (Si), and quartz (SiO2). Thin films from three different discharge modes, in particular, high power impulse magnetron sputtering, midfrequency magnetron sputtering, and radiofrequency magnetron sputtering, are compared. Deposited films are characterized by x-ray diffraction, Raman spectroscopy, and spectroscopic ellipsometry. Composition, crystal structure, and optical properties of as-deposited and annealed films are found to depend on the deposition mode and on the substrate.

The polarization beat length of propagating optical fields in nonlinear birefringent Kerr medium is investigated in the presence of an externally applied DC electric field. We show that the critical power, at which the effective polarization beat length becomes infinite, can be controlled through adjusting the externally applied electric field. The principle of operation is based on modifying the polarization instability by electronically adjusting the effective birefringence through an external electrical bias. The presented analytical expressions describe the beat length and the polarization instability as a function of the applied electric field for an arbitrary optical input state.

We propose and demonstrate analytically, within the framework of a hydrodynamic model, a novel and simpler variational approach to study the asymptotic behavior of a continuous wave (cw) laser beam propagating in a nonlinear nonlocal medium.

Developing efficient techniques to bridge single-plasmon radiations to nanoscale plasmonic waveguides nowadays is still a critical consideration for on-chip integration of solid-state photonic circuits. Here, we propose and theoretically demonstrate the generation and routing of single plasmons in nanowire-based hybrid plasmonic coupling structures with nanodisk antenna resonators. Optimizations of key characteristic parameters illustrate that the structure not only offers an enhanced tradeoff between the propagation length (~20 μm) and mode confinement (~λ 2 /8450), but also exhibits outstanding plasmon generation and guiding properties, such as a Purcell factor of 2.14 × 10 6 , a coupling efficiency from emissions to desired waveguides of 59%, and a Figure-of-Merit of 3 × 10 7 in the visible and infrared spectral range, which outperforms the previous plasmonic structures. The plasmon emission properties are also quite robust against possible emitter positioning imperfections. Our work may inspire new opportunities in helping design quantum-plasmonic platforms for future quantum information processing and related on-chip plasmonic devices.

An original asymptotic method is developed and used to find closed-form approximations to the symmetric thin-film three- and multi-layer plasmonic dispersion equations. Closed-form analysis of three-layer metal-insulator-metal (MIM: "M" is metal and "I" is insulator) and IMI devices shows a complementary physics underpinning their properties. Analysis of multi-layer symmetric devices, considered for a seven-layer MIMIMIM example, uncovers a remarkable departure from the physics governing MIM and IMI features. Multi-layer propagation length and attenuation are determined by proximity, in the space of cladding thickness and wavelength, to singularities that exist in the limit of vanishing imaginary part of the cladding dielectric constant. Exploitation of this phenomenon will expand the development of a broader range of thin-film applications in optoelectronics.

This work is devoted to the identification properties of indium tin oxide (ITO) thin films responsible for their possible application in combined optical and electrochemical label-free sensing systems offering enhanced functionalities. Since any post-processing would make it difficult to identify direct relation between deposition parameters and properties of the ITO films, especially when deposition on temperature-sensitive substrates is considered, the films were deposited using reactive high power impulse magnetron sputtering (HiPIMS) at low temperature and with no post-deposition annealing. We focused mainly on the impact of reactive gases, such as oxygen or nitrogen introduced to the process chamber, on control over plasma parameters and subsequently properties of the films. The properties of the films were investigated using X-ray diffractometry, spectroscopic ellipsometry, four-point probe, and cyclic voltammetry. For presenting optical sensing capabilities, the tailored ITO films in addition to silicon and glass wafers were also deposited on the core of optical fibers to induce the lossy-mode resonance (LMR) phenomenon. The existence of specific deposition conditions resulting in ITO film properties offering both high-quality electrochemical and LMR responses has been experimentally proven. It has been found that the crystalline structure of ITO plays a key role in the determination of both the sensing capabilities. Finally, label-free sensing of antibody-antibody interactions in both optical and electrochemical domains for the sensor with tailored ITO film has been shown.

People in the Middle East are facing the problem of freshwater shortages. This problem is more intense for a remote region, which has no access to the power grid. The use of seawater desalination technology integrated with the generated energy unit by renewable energy sources could help overcome this problem. In this study, we refer a seawater reverse osmosis desalination (SWROD) plant with a capacity of 1.5 m(3)/h used on Larak Island, Iran. Moreover, for producing fresh water and meet the load demand of the SWROD plant, three different stand-alone hybrid renewable energy systems (SAHRES), namely wind turbine (WT)/photovoltaic (PV)/battery bank storage (BBS), PV/BBS, and WT/BBS are modeled and investigated. The optimization problem was coded in MATLAB software. Furthermore, the optimized results were obtained by the division algorithm (DA). The DA has been developed to solve the sizing problem of three SAHRES configurations by considering the object function's constraints. These results show that this improved algorithm has been simpler, more precise, faster, and more flexible than a genetic algorithm (GA) in solving problems. Moreover, the minimum total life cycle cost (TLCC = 243 763$), with minimum loss of power supply probability (LPSP = 0%) and maximum reliability, was related to the WT/PV/BBS configuration. WT/PV/BBS is also the best configuration to use less battery as a backup unit (69 units). The batteries in this configuration have a longer life cycle (maximum average of annual battery charge level) than two other configurations (93.86%). Moreover, the optimized results have shown that utilizing the configuration of WT/PV/BBS could lead to attaining a cost-effective and green (without environmental pollution) SAHRES, with high reliability for remote areas, with appropriate potential of wind and solar irradiance.

In this paper we present a plasma deposition technique that allows the reactive deposition of oxide layers with extremely high deposition rate. The new approach combines reactive sputtering by DC hollow cathode discharge with thermal evaporation from the hot surface of the hollow cathode. As an example of successful fast deposition, photoactive films of titanium dioxide (TiO2) with various thicknesses were deposited using this technique. The uncooled titanium nozzle served as a hot hollow cathode and simultaneously as an inert gas (Ar) inlet. The reactive gas (O-2) was introduced into the vacuum chamber through a separate inlet. During deposition, the temperature of the titanium hollow cathode reached up to 1600 degrees C, depending on the discharge parameters. This made it possible to combine the ion sputtering of hot titanium cathode with its thermal surface evaporation, which significantly increased the TiO2 deposition rate. The highest achieved deposition rate was 567 nm/min (34 mu m/h), which (with respect to the geometry of this process) corresponds to total volume of the deposited TiO2 material 1.2 mm(3)/min per 1 kW of absorbed power. Despite extremely high thermal flux to the substrate, TiO2 films were successfully deposited even on temperature-sensitive PET foil. The as-deposited and post-annealed TiO2 films prepared on fluorine doped tin oxide (FTO) substrates and glass were subject to further analyses including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and photoelectrochemical (PEC) measurements. Whereas the as-deposited TiO2 films had an amorphous (or nearly amorphous) structure, which exhibited only weak photoactivity, after annealing their PEC activity increased by an order of magnitude.