Optical Electronic Devices Research Articles

Engineering Large-Area Antidust Surfaces by Harnessing Interparticle Forces.

Dust accumulation is detrimental to optical elements, electronic devices, and mechanical systems and is a significant problem in space missions and renewable energy deployment. In this paper, we report the demonstration of antidust nanostructured surfaces that can remove close to 98% of lunar particles solely via gravity. The dust mitigation is driven by a novel mechanism, whereby particle removal is facilitated by the formation of particle aggregates due to interparticle forces, allowing the particles to be removed in the presence of other particles. The structures are fabricated using a highly scalable nanocoining and nanoimprint process, where nanostructures with precise geometry and surface properties are patterned on polycarbonate substrates. The dust mitigation properties of the nanostructures have been characterized using optical metrology, electron microscopy, and image processing algorithms to demonstrate that the surfaces can be engineered to remove nearly all of the particles above 2 μm in size in the presence of Earth's gravity. Compared to the 35.0% area coverage on a smooth polycarbonate surface, the particle coverage on nanostructures with 500 nm period is significantly reduced to 2.4%, an improvement of 93%. This work enhances the understanding of the particulate adhesion on textured surfaces and demonstrates a scalable, effective solution to antidust surfaces that can be broadly applied to windows, solar panels, and electronics.

DESIGN OF A PERMITTED NETWORK USING FIBER-OPTIC-BASED SOLUTIONS MATHEMATICAL MODELING

The main goal of the research is to increase the speed of exchange in broadband subscriber access networks, primarily using PON technology, since the needs of subscribers are constantly growing and modern structures can no longer provide them. This article discusses the PON technology, types of WDM technology, equipment designed for communication networks using WDM, designs and parameters of WDM multiplexers. The possibility of implementing WDM-TDM hybrid multiplexing in existing PON systems is considered. Conclusions are drawn about the relevance of the use of this technology in order to modernize existing access networks. The rapid development of technologies for the production of electronic optical devices and optical fibers made it possible in the mid-80s to use fiber to connect individual users and organizations. The launch of the first distribution networks was carried out using point-to-point topologies, but a few years later the technology of passive optical networks (PON) was created, which allows organizing point-to-point topologies.

Analysis of methods for detection of anomalies in video series of video surveillance camera on vehi-cles

Problem. Video surveillance is a process of monitoring various objects, which is implemented with the use of video cameras - optical-electronic and microprocessor devices, designed for visual control of the environment, with the aim of the safety of life, activity and property of a modern person. Such processes and objects can be, for example, cars moving at an intersection, on a street or on a country road, a road surface during the control of its condition and quality, a security system of any infrastructure object. Goal. The purpose of the study is the analysis of the technical composition of systems for detecting anomalies in the video of video surveillance cameras and a comparative review of computational methods for processing the results of this observation. To achieve the goal, it is necessary to research literary sources, that is, articles in scientific journals, reports at conferences, articles on non-thematic web portals, monographs and textbooks, the names of which indicate the possibility of finding information useful for this research. Methodology. As part of the research task, we are interested in the technologies, systems and methods that have been proposed and developed for obtaining, processing and analyzing video sequences and images, including machine vision tasks, image classification, object and anomaly detection, image segmentation, etc. Results. As a result of this research, the following was done: 1) An overview of the main modern systems for detecting anomalies in the video series of video surveillance cameras was conducted. It was concluded that the differences between the anomaly detection systems in the video series of video surveillance cameras are due to the choice of methods for processing video information. 2) An analysis of methods of detecting anomalies in the video series of video surveillance cameras was carried out. For this purpose, a classification of modern methods of detecting anomalies in the video series was developed and the basics of the theory of deep neural networks were considered in terms of the possibility of their application for classification, localization, segmentation, detection, identification and tracking of objects in the video series of surveillance cameras. Originality. An overview of the main modern systems for detecting anomalies in the video series of video surveillance cameras was conducted. It was concluded that the differences between the systems for searching for anomalies in the video series of video surveillance cameras are determined by the choice of methods for processing video information. An analysis of the methods of detecting anomalies in the video series of video surveillance cameras was carried out. Practical value. The developed information system is already used to provide students of all educational institutions of Ukraine of the III level of accreditation with the information about our university; regarding the specialties offered by the university and the corresponding professions; regarding open days, preparatory courses and much more.

Perturbation based analytical and numerical solutions of non-Newtonian differential equation during reverse roll coating process under lubrication approximation theory

Reverse roll coating process are utilized for the purpose of applying a coating to a substrate or web by utilising different rollers in order to get the required coated surface. As a result of this, reverse roll coating process have found applications in a wide variety of industries, such as those dealing with food and medicine, electronic components, optical and LCD devices, and optical products. The main objective of this paper is to develop the mathematical formulation for the coating of thin film for an incompressible isothermal viscoelastic fluid between two reversely rotating rolls. Through the use of an appropriate dimensionless parameter, Non-dimensional nonlinear ordinary differential equations (ODEs) are derived from governing partial differential equations (PDEs). LAT (lubrication approximation theory) simplifies the dimensionless equations of fluid motion. The expressions for velocity of flow, pressure gradient and flow rate is obtained analytically by using regular perturbation method, while numeric solution of some mechanical parameters such as power input, coating thickness, roll separation force and separation points are calculated. The numerical validation of the analytical solution of the fundamental model of nonlinear constitutive flow laws is done in the Maple environment using the numeric technique which is based on finite difference method. The influence of numerous non-Newtonian parameters such as velocities ratio and Weissenberg number on velocity profiles, pressure gradient, power input, roll separation force, separation points and coating thickness of a non-Newtonian Johnson–Segalman (JS) fluid are explored via graphically and in tabular form. The outcomes demonstrate that on increasing the Weisenberg number and velocities ratio, the coating thickness on web is decreases. For the numerous values of velocities ratio, it is important to note that separation points shifted towards the nip region. In addition, the non-Newtonain parameter have signifcant impact on power input and roll separating force. The maximum coating thickness that is 1.0927 has been observed at the value of separation poin 0.9620. Hence, these factors may help in an efficient coating process and improve the substrate life.

Optical and Electrical Characterization of Visible Parylene Films.

Poly-dichloro-para-xylylene (parylene-C) film is formed through a chemical vapor deposition process, where monomeric gases are polymerized on the target surface at room temperature and are used as transparent insulating coating films. The thin parylene-C films exhibit uniform conformal layers even when deposited on substrates or surfaces with fine cracks, structures, and bumps. However, the film is highly transparent in the visible range (transmittance > 90%); thus, it is difficult to visually identify, inspect the coating process and check for any defects when used as an insulation film. Some reports have demonstrated the deposition of visible (hazy) parylene films through the control of the vaporization or pyrolysis of the parylene-C powder and sublimed dimers, respectively. Even though these films have been applied as device substrates and light extraction layers in organic light-emitting diodes (OLEDs), their optical and electrical characteristics have not been extensively explored, especially for their applications as insulation coatings. In this study, the characteristics of visible parylene films produced by tuning the ratio of dimer to monomer gases via the adjustments of the pyrolysis temperature are analyzed with electrical and optical methods. Parylene-C films deposited within the pyrolysis temperature of 400–700 °C exhibited a haze range of 10–90%. A relative reflectance of 18.8% at 550 nm of the visible light region was achieved in the visible parylene film deposited with a pyrolysis temperature of 400 °C. Resistivity in the order of 1010 Ω cm was achieved for the visible parylene films measured with the transmission line measurement (TLM) method. The films can be applied in advanced insulation coatings for various optical systems and electronic devices.

Color vision devices for color vision deficiency patients: Asystematic review and meta-analysis.

Background and AimsThere is insufficient evidence to support that using electronic or optical color vision devices improve color perception with current advanced technology. The purpose of this study is to compare and analyze the different color vision devices available for patients with color vision deficiency (CVD) and evaluate whether these devices improved their color perception.MethodsThis review included randomized, experimental, comparative studies, as well as narrative reviews, prototype and innovation studies, and translational studies, followed by case‐control and clinical trials with nonsurgical interventions studies, that is, electronic color vision devices, optical devices, and contact lens‐based studies, with standardized inclusion and exclusion criteria.ResultsThe primary outcome studied was the performance of color vision devices, both objective and subjective. Secondary outcomes included the ease of use and accessibility of color vision devices and technology. The grading of recommendation, assessment, development, and evaluation framework was used to develop a systematic approach for consideration and clinical practice recommendation for CVD devices for color‐deficient populations. We incorporated meta‐analysis reports from a total of n = 16 studies that met the criteria which consisted of case‐control studies, prototype and innovation studies, comparative studies, pre‐ and post‐clinical trial studies, case studies, and narrative reviews. Proportion and standard errors, as well as correlations, were calculated from the meta‐analysis for various available color vision devices.ConclusionThis review concludes that commercially available color vision devices, such as EnChroma Glasses, Chromagen filters, and EnChroma Cx‐14 do not provide clinically significant evidence that subjective color perception has improved. As a result, recommending these color vision devices to the CVD population may not prove high beneficial/be counterproductive. However, only a few color shades can be perceived differently. This systematic review and analysis will aid future research and development in color vision devices.

Effect of different in situ temperatures on the crystallinity and optical properties of green synthesized 8-hydroxyquinoline zinc by saffron extract

In this research, bis (8-hydroxyquinoline) zinc (ZnQ2) nanoparticles were synthesized by the saffron extract method in a water environment at room temperature using a simple chemical precipitation method. Based on this technique, saffron was utilized as a surfactant due to its non-toxicity and being environmentally friendly. The existence of C-H bonds in the compound of saffron makes it an appropriate material for the green synthesis of ZnQ2 nanoparticles. These kinds of bounds cause reduce the rate of agglomeration of ZnQ2 nanoparticles while of the synthesis process. In this project, the ZnQ2 nanoparticles were synthesized using saffron non-toxic surfactant in different temperatures. The temperature effects from room temperature to 200 °C were considered on the crystal structure of ZnQ2 nanoparticles and their effect on optical properties, an in-situ HT-XRD instrument has been used. The functional groups of the compound, structural, morphology, and fluorescence properties of ZnQ2 nanoparticles were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), photoluminescence (PL) spectroscopy, and Ultraviolet-visible spectroscopy (UV-Vis). According to the results, XRD analysis confirmed the crystalline nature of the synthesized ZnQ2 nanoparticles by the saffron extract. The same bounds were achieved at various temperatures and also with the increase in temperatures of synthesis at 200°C sizes and band gaps were altered from 3.4 nm to 2.5 nm. Therefore, the ZnQ2 nanoparticles are one of the best green materials for replacing transferred electrons materials in optical devices. In conclusion, with utilizing the green materials, Because of reduction the intensity of surface trap and absorption is reduced and the PL of ZnQ2 in the 50°C have reached to 20000. This could be an excellent perspective for using green materials in the organic light-emitting diode and other electronic-optical devices.

Current and Future Trends for Polymer Micro/Nanoprocessing in Industrial Applications.

Polymers are widely used in optical devices, electronic devices, energy-harvesting/storage devices, and sensors, owing to their low weight, excellent flexibility, and simple fabrication process. With advancements in micro/nanoprocessing techniques and more demanding application requirements, it is becoming necessary to realize high-resolution fabrication of polymers to prepare miniaturized devices. This is particularly because conventional processing technologies suffer from high thermal stress and strong adhesion/friction, which can irreversibly damage the micro/nanostructures of miniaturized devices. In addition, although the use of advanced fabrication methods to prepare high-resolution micro/nanostructures is explored, these methods are limited to laboratory research or small-batch production. This review focuses on the micro/nanoprocessing of polymeric materials and devices with high spatial precision and replication accuracy for industrial applications. Specifically, the current state-of-the-art techniques and future trends for micro/nanomolding, high-energy beam processing, and micro/nanomachining are discussed. Moreover, an overview of the fabrication and applications of various polymer-based elements and devices such as microlenses, biosensors, and transistors is provided. These techniques are expected to be widely applied for multiscale and multimaterial processing as well as for multifunction integration in next-generation integrated devices, such as photoelectric, smart, and biodegradable devices.

Photo‐isomerization, photodimerization, and photodegradation polyimides for a liquid crystal alignment layer

AbstractWe review the important features of LC orientation for the alignment layer, namely, production method, alignment mechanisms, and required properties. Photoalignment, which could eliminate the disadvantages of the rubbing method is explored. Applicable materials and techniques for photoalignment are also examined. Many materials for photoalignment layers have been proposed, but polyimide‐based materials are commonly used because of their transparency and insulation properties, which are needed for optical electronic devices. Furthermore, photoisomerization, photodimerization, and photodecomposition as photoalignment methods are reviewed, and specific photoreactive groups and alignment mechanisms are used to induce LC alignment. In summary, polyimides cause photodecomposition and have the following disadvantages; (1) requirement of relatively short‐wavelength ultraviolet (UV) irradiation, (2) difficulty in reorienting polymer chains owing to their rigid polymer matrix, and (3) low‐photo reactivities. The solutions for each disadvantage are already proposed, but the required properties should be determined during material design. Polyimide‐based materials introduced with the azobenzene and cinnamate groups are proposed and found to have the ability of fulfilling the required properties. The mechanism of polyimide photodecomposition is not fully understood. It likely has the advantage in terms of LC alignment stability because of the absence of E/Z isomerization. Therefore, the alignment mechanism and availabilities should be further explored.

SUBSTANTIATION OF NECESSITY OF VIDEO INFORMATION PROCESSING ON BOARD THE RECCONNAISSANCE UNMANNAED AERIAL VEHICLE

The combat capabilities of the recconnaissance unit depend on the effectiveness of recconnaissance during the assessment of the area of operation of the unit. The methods of video processing significantly impact the quality of the task assigned to the unit. Fast and high-quality processing of video air reconnaissance allows to carry out analysis, predict trends of changes in the defensive positions of the enemy, determine their strength and location, concentration of forces for the offensive or raid. The biggest problems are connected with real-time data transmission and solving tasks that need to be solved in order to use a large number of computing resources.
 The variety of digital imaging techniques and algorithms is associated with a wide range of problems that arise during the processing and transmission of digital data.
 To solve important practical tasks, including the identification of useful optical signals and images on the background of interference, integrated designs are created, in which matrix receivers of the emission are combined with electronic image processing systems. At the same time, many modern articles do not take into account a number of new factors and problems related to, for example, the sharp increase in the volume of information to be processed in real time, with peculiarities of space and time selection of high definition, etc.
 The peculiarities of the choice of algorithms of digital image processing in the optical-electronic devices of UAV significantly affect the probability of detection of trace objects and combat capabilities of the UAV in general.

The Negative Photoconductivity of Ag/AgO Grown by Spray-Pyrolysis

The main goal of this work is to provide a general description of the negative photoconductivity effect observed in Ag/AgO films grown by the spray-pyrolysis technique. X-ray diffractograms display hybrid films with high texturized AgO and metallic Ag phases. Scanning electron microscopy images show small Ag particles on the surface. Due to its surface nature, X-ray photoelectron spectroscopy revealed the predominance of the metallic character of Ag 3d spectra as compared to Ag2+. Negative photoconductivity with photoresponse in the order of seconds is observed under several wavelengths of excitation. We found that the amplitude of the negative photoresponse is strongly dependent on the optical absorbance and enhanced by surface plasmon resonance. The low-cost technique employed and the special features regarding negative photoconductivity provide an exciting platform for developing optical-electronic devices with low power consumption.

State of the art of ultra-thin gold layers: formation fundamentals and applications.

Fabrication of ultra-thin gold (Au) layers (UTGLs) has been regarded as the key technique to achieve applications with tunable optical response, flexible sensors and electronic devices. Various strategies have been developed to optimize the wetting process of Au, resulting in the formation of UTGLs at a minimum thickness. The related studies on UTGLs attracted huge attention in recent years. On the one hand, the growth processes of UTGLs on different substrates were in-depth probed by advanced in situ characterization techniques and the effects of optimization strategies on the growth of UTGLs were also revealed. On the other hand, based on the understanding of the growth behavior and the assistance of optimization strategies, various applications of UTGLs were realized based on optical/plasmon responses, surface-enhanced Raman scattering and as electrodes for various sensors and electronic devices, as well as being seed layers for thin film growth. In this focused review, both the fundamental and practical studies on UTGLs in the most recent years are elaborated in detail. The growth processes of UTGLs revealed by in situ characterization techniques, such as grazing-incidence small-angle X-ray scattering (GISAXS), as well as the state of the art of UTGL-based applications, are reviewed.

A Tough Reversible Biomimetic Transparent Adhesive Tape with Pressure-Sensitive and Wet-Cleaning Properties.

Dry adhesives that combine strong adhesion, high transparency, and reusability are needed to support developments in emerging fields such as medical electrodes and the bonding of electronic optical devices. However, achieving all of these features in a single material remains challenging. Herein, we propose a pressure-responsive polyurethane (PU) adhesive inspired by the octopus sucker. This adhesive not only showcases reversible adhesion to both solid materials and biological tissues but also exhibits robust stability and high transparency (>90%). As the adhesive strength of the PU adhesive corresponds to the application force, adhesion could be adjusted by the preloading force and/or pressure. The adhesive exhibits high static adhesion (∼120 kPa) and 180° peeling force (∼500 N/m), which is far stronger than those of most existing artificial dry adhesives. Moreover, the adhesion strength is effectively maintained even after 100 bonding-peeling cycles. Because the adhesive tape relies on the combination of negative pressure and intermolecular forces, it overcomes the underlying problems caused by glue residue like that left by traditional glue tapes after removal. In addition, the PU adhesive also shows wet-cleaning performance; the contaminated tape can recover 90-95% of the lost adhesion strength after being cleaned with water. The results show that an adhesive with a microstructure designed to increase the contribution of negative pressure can combine high reversible adhesion and long fatigue life.

Quadratic optical responses in a chiral magnet

Chiral magnets, which break both spatial inversion and time reversal symmetries, carry a potential for quadratic optical responses. Despite the possibility of enhanced and controlled responses through the magnetic degree of freedom, the systematic understanding remains yet to be developed. We here study nonlinear optical responses in a prototypical chiral magnetic state with a one-dimensional conical order by using the second-order response theory. We show that the photovoltaic effect and the second harmonic generation are induced by asymmetric modulation of the electronic band structure under the conical magnetic order, and the coefficients, including the sign, change drastically depending on the frequency of incident lights, the external magnetic field, and the strength of spin-charge coupling. We find that both effects can be enormously large compared to those in the conventional nonmagnetic materials. Our results would pave the way for next-generation optical electronic devices, such as unconventional solar cells and optical sensors, based on chiral magnets.

Water-based flexographic ink using chalcones exhibiting aggregation-induced enhanced emission for anti-counterfeit applications

In pursuit of fluorescent pigments, a pyrene-based chalcone 1-(4-chlorophenyl)-3-(3a1,6,8a,10a-tetrahydropyrene-1-yl)prop-2-en-1-one (CPP), which exhibited aggregation-induced enhanced emission was synthesized. Water-based eco-friendly flexographic inks were formulated using CPP (in batch ink) and Luminous yellow RG-3 (in standard ink) as pigments. The batch and standard inks were coated on security paper and printed on security and packaging papers as well as boards. The printed substrates displayed yellow fluorescence upon excitation under UV light. The gloss, light-fastness, abrasion resistance and colorimetric values of the batch ink were superior to that of standard ink. The study revealed the potential of CPP as a fluorescent pigment for security printing applications, optical-electronic devices such as transistors, anti-counterfeiting labels, etc.

In Situ Electrohydrodynamic Jet Printing-Based Fabrication of Tunable Microlens Arrays

Tunable microlens arrays (MLAs) with controllable focal lengths have been extensively used in optical sensors, biochips, and electronic devices. The commonly used method is electrowetting on dielectric (EWOD) that controls the contact angle of the microlens to adjust the focal length. However, the fabrication of tunable MLAs at the microscale remains a challenge because the size of MLAs is limited by the external electrodes of EWOD. In this study, a highly integrated planar annular microelectrode array was proposed to achieve an electrowetting tunable MLA. The planar microelectrode was fabricated by electrohydrodynamic jet (E-jet) printing and the liquid microlens was then deposited in situ on the microelectrode. This method could realize 36 tunable liquid microlenses with an average diameter of 24 μm in a 320 × 320 μm2 plane. The fabricated tunable MLAs with higher integration levels and smaller sizes can be beneficial for cell imaging, optofluidic systems, and microfluidic chips.

Crystallization-Induced Enhanced Electrochemiluminescence from Tetraphenyl Alkene Nanocrystals for Ultrasensitive Sensing.

Organic materials with diverse structures and brilliant glowing colors have been attracting extensive attention in optical electronic devices and electrochemiluminescence (ECL) fields and are currently faced with the issue of low ECL efficiency. Herein, a series of tetraphenyl alkene nanocrystals (TPA NCs) with an ordered molecular structure were synthesized to explore regularities in the crystallization-induced enhanced (CIE) ECL emission effects by altering the number and position of vinyl on the backbone of TPA molecules. Among those TPA NCs, tetraphenyl-1,3-butadiene (TPB) NCs exhibit the brightest ECL emission via a coreactant pathway, with the relative ECL efficiency of up to 31.53% versus the standard [Ru(bpy)3]2+/TEA system, which is thousands of times higher than that of free TPB molecules. The high ECL efficiency of TPB NCs originates from the effective electron transfer of unique J-aggregates on the a axis of the nanocrystals to notably promote radiative transition and the restriction on the free rotation of TPB molecules to further suppress the nonradiative transition, which has exhibited great potential in ultrasensitive biosensing, efficient light-emitting devices, and clear ECL imaging fields. As a proof of concept, since dopamine (DA) can form benzoquinone species by electrochemical oxidation to realize intermediate radical quenching and excited-state quenching on the TPB NCs/TEA system, the TPB NCs with the CIE ECL effect are used to construct an ultrasensitive ECL-sensing platform for the determination of DA with a lower detection limit of 3.1 nM.

반도체 전자소자 기반 테라헤르츠 신호원

Terahertz (THz) signal sources are important elements that are used in THz systems and have been gaining interest in recent times. THz signal sources can be realized using either optical devices or electronic devices. The latter approach can be divided into signal sources based on vacuum devices and solid-state devices. This paper provides an overview of THz sources that use semiconductor electronic devices, which are a typical kind of the solid-state devices. First, the operational principles and recent performance trends of diode-based THz signal sources, such as Gunn diodes, impact ionization avalanche transit-time (IMPATT) diodes, and resonant tunneling diodes (RTDs), are provided. Next, three types of transistor circuit-based THz signal sources, namely, LC cross-coupled oscillators, Colpitts oscillators, and ring oscillators, are described according to their topologies and performance. Finally, various types of 300 GHz and 600 GHz oscillators are introduced as representative examples of transistor circuit-based signal sources.

Strain-tunable electronic and optical properties of novel MoSSe/InSe van der Waals heterostructures

van der Waals heterostructures (vdWHs) have been widely studied due to their particular properties. In this work, the electronic structure and the optical properties of MoSSe/InSe vdWH are studied by first-principles calculations, and the changes of strain modulation properties are also discussed. Theoretical research shows that the MoSSe/InSe vdWHs have an indirect band gap and the band alignments are type-I and type-II correspond to two different stacking patterns, respectively. Compared with MoSSe and InSe monolayer, the optical absorption of the MoSSe/InSe vdWH in the visible and ultraviolet region is improved. In addition, the band gap, the band alignment, and the optical absorption of the MoSSe/InSe vdWH can be effectively modulated by biaxial strain. This work provides possibilities for the application of the MoSSe/InSe vdWH in optical devices, electronic devices and photocatalysis.

The transparent NiO film ohmic contact to p-type and unintentionally doped In0.53Ga0.47As

The NiO thin film ohmic contact to the p-type In0.53Ga0.47As and non-doped In0.53Ga0.48As was experimentally demonstrated. The ohmic contact mechanism is mainly due to the small valence band offset between the NiO and InGaAs. The NiO thin film was synthesized through thermal oxidation. The oxidation time is the key factor affecting the contact properties of the NiO/InGaAs. It is promising for the application of NiO transparent electrodes in III-V compound material-based optical-electronic devices.