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This study explores the memory effect in nematic liquid crystals (NLCs) when doped with various nanoparticles. The experimental approach focused on observing how changes in the dopand and concentration of nanoparticles affect the light transmission through NLCs under applied external field. Such insights are invaluable for designing next-generation liquid crystal devices with tailored properties for specific applications, ensuring optimal performance and durability with introduction of role of nanoparticles in LC systems. It is evident that while some nanoparticles like SiO2 enhance the memory effect, others like Fe3O4 might introduce undesirable complexities. The enhanced memory effects facilitated by nanoparticles open numerous applications in advanced display technologies, including flexible displays and high-resolution screens. Additionally, the findings have significant implications for the design of optical switches and sensors that operate under low-power conditions, enhancing the energy efficiency of these devices. [ABSTRACT FROM AUTHOR]

Tin nanoparticles (SnNP) thin films were prepared by the thermal evaporation method. The effect of thin film thickness upon the structural, thermal, and optical properties has been studied. The SnNP thin films thickness was 52.3 nm, which has developed upon a glass substrate held at the room temperature. X-ray diffraction (XRD), Field Emission-Scanning Electron Microscope (FE-SEM), and Atomic Force Microscopy (AFM) were used to evaluate the characterization of SnNP thin films. The optical properties represented by absorption were also studied via Ultraviolet-Visible (UV-Vis) spectroscopy with a wavelength range of (300-1200) nm. The optical transmission spectra suggested that the energy band gap reduces with raising the film thicknesses. Results manifested that the SnNP sizes obtained ranged from 61.26 - 62.14 nm, with a semi-spherical shape, while the average surface roughness of SnNP was found 13.2 nm and at an average grain size of 113 nm, and the SnNP. thin film thickness was 52.3 nm for coating time (2) min. On the other side, the absorbance tests elucidated the maximum value for absorbance at a 389.3 nm wavelength. [ABSTRACT FROM AUTHOR]

Photonic crystals (PC) are atomic materials that have a periodic structure on the optical wavelength scale and can inhibit light transmission at specific wavelengths. In this paper, we use the literature study method with a review of several journals to see the Plane Wave Expansion (PWE) method for calculating the two-dimensional photonic bandgap. The calculation of the band gap of the photonic crystal model in this paper is carried out for a cylindrical 2D periodic lattice and the lattice structure model used is a triangular lattice and a square lattice. From the calculation results, it is concluded that the calculation results for R<0,5a do not show a bandgap. While the calculation results of R<0,5a or R>0,5a on the TM polarization show a band gap. [ABSTRACT FROM AUTHOR]

Organic nonlinear optical material N'-[(E)-(5-bromofuran-2-yl)methylidene]-2-(6-chloropyridin-3-yl)acetohydrazide (BCA) was synthesized by the reflux method, and single crystals were grown by slow evaporation technique. Optical absorbance was investigated by using UV–Vis–NIR spectrophotometer and obtained the optical transmission bandwidth (200 nm to 1100 nm), lower UV cut-off wavelength (333 nm), and optical band gap (3.30 eV) parameters. The second harmonic generation (SHG) efficiency of BCA was determined using Kurtz and Perry powder technique, and it was 1.3 times greater than that of the KDP crystal. Frontier molecular orbital (FMO) analyses of BCA were performed by density functional theory (DFT) with a B3LYP/3-21G basis set. Further, the nonlinear optical static and dynamic parameters (second and third-order) were computed to demonstrate the compound's suitability for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Fabrication of lithium sulfate (Li2SO4) thin films has been successfully attempted using the electron-beam evaporation technique, and the deposition conditions were systematically optimized to get stable Li2SO4 thin films. Thin films have been prepared under the pressure of 8×10−4 mbar on glass and quartz substrates. The thin film deposited on quartz substrates was used for optical studies. The optical properties of the fabricated films were investigated using optical transmission spectroscopy measurements. A transparency of 80 % and a lower cut-off wavelength at 320 nm were measured from the UV-vis spectrum for Li2SO4 thin film. Further, the band gap value of the thin film is compared with that of Li2SO4 powder, which was obtained by DRS measurement. [ABSTRACT FROM AUTHOR]

Optical transmission characterization has been done in the vacuum evaporated thin films of Ge25S75-xSbx (x = 0, 10) chalcogenides in the wavelength range 300 to 3100 nm. Swanepoel's method is used for the analysis of various linear optical parameters. Tauc's relation is used for the estimation of optical band gap (Eg). Recent optical applications of present glassy materials have been discussed on the basis of linear optical parameters. [ABSTRACT FROM AUTHOR]

The optical transmission and UV-VIS absorption spectra for PVA/Aniline blends were obtained in the wavelength range (200-1100). Before and after gamma radiation with Co60 were. FTIR spectrophotometer was used to determine the chemical structure. The optical energy gap and optical constant like refractive index (n) have been assessed. Our result indicates that the materials have allowed direct transition and the value of energy gap changed with the gamma dose exposed to it. [ABSTRACT FROM AUTHOR]

Wireless underwater communication refers to the propagation of data using a wireless channel through the water. Underwater wireless optical communication (UWOC) gained large attention in the past years owing to its distinguished capability of transferring a high rate of data for longer distances. It can be beneficial in different applications like environment protection, exploration of the seawater, military operations, emergency alarms and so on. However, the underwater field represents a difficult medium to deal with as the channel subjected to scattering and severe absorption. Besides that, the challenge of accurate localization makes the connections improperly adjusted, which in turn affects the signal propagation quality. Recently many innovating techniques of network have been proposed to overcome these difficulties which differ from optical transmission in vacuum. In our review we discussed numerous approaches and achievements in UWOC. [ABSTRACT FROM AUTHOR]

Currently, global demand of optical sensors continues to thrive due to human need for fast and reliable networks. For this reason, optical sensors such as waveguide continue to be optimized in every aspect, one of which is in its mechanical properties, such as resistance to pressure etc. Stress and strain experienced by waveguide is one of the causes of failure in the transmission of light in waveguide. Many research carried out the stress and strain of waveguide but rarely considers the effect of adhesive to waveguide. The purpose of this study is to find the most optimum adhesive properties based on its effect on the stress and strain on the waveguide with cores in the form of Polymethyl Methacrylate (PMMA) and silicone rubber as part of its cladding. This study used ABAQUS 2017 software to simulate waveguide conditions with epoxy-based adhesive variations, each variation Tra-Con F113, Epotek 301-2 and Hysol 9361 are further simulated into spring elements as core interface and cladding models with adhesive spring constants of 5330 N/mm, 12.300 N/mm and 18.320 N/mm. Models are pressured 20, 40, 60, 80 and 100 MPa. Each model is then researched, and the results are recorded. Based on the data, the most optimum adhesive is Hysol 9361 with an adhesive spring coefficient of 18.320 N/mm at maximum pressure conditions resulting in the highest safety factor of 1.11 and the smallest strain of 0.07. [ABSTRACT FROM AUTHOR]

Hybrid materials attract numerous interests in various industrial applications nowadays. Integration of nanoparticles with electric, magnetic, and semiconducting properties are used to tune liquid crystals basic properties to increase or decrease their behaviour under applied external magnetic or electric fields. Synthetized nanoparticles shapes and concentrations defines their interactions with liquid crystal host. In this contribution, various liquid crystals (LC) and dopands are investigated under applied external magnetic or electric field, considering the colloidal stability and structural changes in host LCs. To examine these changes acoustic spectroscopy utilizing SAW (surface acoustic wave) and optical transmission techniques were used. The doping with nanoparticles affects both threshold field and nematic-isotropic transition shift which can be registered by SAW attenuation or optical transmittance change. The effect of particle concentration and size plays an important role for orientational coupling between dipole moments of LC molecules and nanoparticles. Therefore, the magnitude of structural changes invoked by the external field are dependent from these parameters. [ABSTRACT FROM AUTHOR]

Transparent wood is wood that allows light to pass through its structure. This is opposed to the nature of wood structure which is normally opaque and has solid structure that block the path of light. Wood that allows light transmission has the advantage of shatterproof material, which could be made suitable to replace glass in various applications. The transparent wood may reduce percentage in energy consumption in building sector as it has low thermal absorption with good optical properties. In this project on path to transparent wood, the suitable time for delignification and the tensile of transparent wood was looked at. The experiment was done using two types of wood species (red meranti & white meranti) in veneer form with thickness of 1.5mm. The delignification process was tested for 3 h, 6 h, 9 h and 12 h with 0 h as control. It was found that 9 hours is adequate to be use in delignification of wood. For all delignified sample, transparency was evident. The tensile test showed that the 3 hours has the best value which the lignin content was 19.1%. The incorporation of wood with suitable resin with correct processing will create a renewable product. [ABSTRACT FROM AUTHOR]

The modulation formats play an important role in providing speed and efficiency of the internet and data transmission though optical fiber. The concept of coherency in optical communication has gained popularity because coherent optical communication provides better spectral efficiency, more efficient way of managing non-linear impairments, better sensitivity, an increased capacity with use of DSP (Digital Signal Processing) and a support for the multilevel modulation formats. Coherent communication technology gives rise to advanced modulation formats compared to Intensity Modulation Direct Detection (IM-DD) counterparts. This paper presents a comparison-based analysis to investigate the suitability of various modulation formats available for fiber-optic coherent communication. The selection of a suitable modulation format for coherent optical transmission through fiber is required in order to obtain optimal transmission efficiency and speed. [ABSTRACT FROM AUTHOR]

Wave propagation is a fundamental phenomenon occurring in several physical systems. this study include the effect of frequency chirping on optical communication device efficiency is investigated theoretically using a simplistic but realistic model for chirped pulses produced in optical fibers that are directly modulated. The propagation of Gaussian and super-Gaussian chirped pulses in a fiber is being considered, by conversant with the Fourier representation for a pulse propagating in a optical fibers(OFs), the idea of the pulse spectrum and conversant with the algorithm for performing linear pulse propagation in a fiber using Fourier transforms. The study will be able to perform discrete Fourier transforms used in the numerical evaluation of Fourier transforms, and through this, one will recognize the reliability of the pulse amplitude along the fiber as well as the intensity of the time for the pulse takes with super-Gaussian pulse, The effect of chirp on the propagation pulse during the optical fiber was also studied, where it was found that the transmission of messages sent during the pulse was not able to transmit the presence of chirp and the appearance of clear distortions in the form and amplitude of the propagation pulse. [ABSTRACT FROM AUTHOR]

The objective of this work is samples are treated by the dc plasma system for different gases (oxygen, argon, and nitrogen) that utilizing to modulate (PMMA) polymethyl methacrylate surface and contrast results with untreated samples. UV- Visible Spectroscopy has characterized the optical properties of plasma-treated membranes. Fourier Transformation Infrared Spectroscopy has been characterized by changes in the chemical composition. The results (FTIR) revealed differences in the molecular bond of polymer chains in the polymer membranes' surface structure. The findings of UV-Visible spectroscopy clearly demonstrate a decrease in the transmission of light due to plasma therapy, as well as imaginary and real portions of the dielectric and refractive constant of the samples various are determined utilizing the absorption, reflection, and transmission spectrum of the samples and determined the energy gap. [ABSTRACT FROM AUTHOR]

Now a days, 532 nm Laser whose spectrum is visible in nature, is used in different applications like Lidar, optical wireless communication, in-car headlight projector to detect the object and reduce the accident in foggy weather conditions, as a pilot laser for alignment the non-visible infrared spectrum of OWC link purpose, etc. Different states of India, as well as West Bengal, faces foggy weather conditions, especially in the winter season. This foggy environment can create a problematic situation for the above-mentioned applications. This experimental simulation has been done by taking the reference of the last twelve years' average visibility data of some districts of West Bengal in the winter season. In these experiments different visibility phenomenon has been created with an artificial fog machine in a 15 feet fog chamber and a 25 ft. optical transmission range has been considered. This simulated foggy environment has been validated by Kim Model of foggy environment. optical power attenuation has been studied concerning different visibility conditions. [ABSTRACT FROM AUTHOR]

To obtain high-quality video images characterizing the ecological condition of the underwater marine environment in real time, it is necessary to create modern automated systems for accumulating and processing video information, which are aggregated from autonomous underwater devices equipped with special technical means of control, in particular, television cameras. Technologies for environmental monitoring using these systems make it possible to study the seabed for the presence of unfavorable environmental factors and foreign objects, to identify them, as well as to map the seabed topography in order to provide the coordination center with a full volume of data on the bottom ecological situation. All this requires high-resolution video transmission from autonomous underwater devices. The traditional hydroacoustic underwater systems for accumulating and processing video information are being replaced by open systems for its optical transmission and reception, based on laser technologies. An obstacle for the wider use of hydroacoustic fields is the low speed of video information transmission to surface objects. The article substantiates the expediency of using open optical communication systems to create high-speed underwater information telecommunications, among which the most preferable are laser systems that have sufficient broadband, which is necessary to ensure a high video stream speed. [ABSTRACT FROM AUTHOR]

The paper investigates the effect of nanocomposite coatings on centrosymmetric bending strength σbB and light transmission factor in visible band of a glass specimens. The coatings on the basis of Al-Si-N and In-Sn-O systems deposited on the surface of quartz specimens (KV grade) using pulsed magnetron sputtering. The deposition of In-Sn-O coating on the glass more prominently, ∼1.6 times, increases the value of σbB as compared to ∼1.3 times which is typical for Al-Si-N coating. Coatings based on In-Sn-O more effectively increased the cracking resistance of quartz glass. [ABSTRACT FROM AUTHOR]

Supramolecular self-assembly of water-soluble p-tert-butylthiacalix[4]arene derivatives containing betaine fragments in cone and 1,3-alternate conformations in the presence of silver (I) and copper (II) nitrates were studied. The influence of macrocycle conformation on the size and shape of obtained associates was shown by dynamic light scattering and transmission electron microscopy. The obtained betaine derivatives of thiacalix[4]arene in cone conformation form spherical nanoparticles with silver nitrate, while the compounds in 1,3-alternate conformation forms branched structures. It was also shown that the compounds in 1,3-alternate conformation form large spherical dendrite structures with copper (II) nitrate. [ABSTRACT FROM AUTHOR]

In this work, we propose a new structure of 1×3 beam splitter with photonic crystal (PhC) waveguide in order to improve their optical characteristics such as higher optical transmission power and lower losses. At first, we design a two dimensional (2D) triangular lattice structure consisting of circular air holes drilled in a silicon slab for 1550 nm of wavelength. Then, we use a structure in Y-junction waveguides with a large separating angle for designing a photonic crystal 1×3 beam splitter. The proposed 1×3 beam splitter consists of two different 1×2 beam splitters. The first 1×2 beam splitter has an unequal power distribution with two splitting ratios of 1/3 and 2/3 in both output ports. In this first splitter, we have introduced a Drop Houl defect in their distribution zone for having unequal division. The second one is a 1×2 beam splitter with an equal power distribution. Finally, the optical characteristics of the modified structure of photonic crystal 1×3 beam splitter are numerically analyzed by FDTD method. The obtained results show that the proposed photonic crystal 1×3 splitter has a total of transmission efficiency about 92% at 1550 nm and 1573 nm, respectively. An equal power distribution has been obtained about 31% in each output power. The proposed splitter also exhibited a transmission loss lower than 10%. [ABSTRACT FROM AUTHOR]

In the last decades, research on visible light communication (VLC) has been attracting researchers to develop a wireless communication system based on visible light transmission. The advancement of LEDs for the lighting system is a factor in considering it for wireless communication purposes. Even though this technique can perform lighting and communication simultaneously for green communications, it suffers attenuation on the emitted power as distance increases and divergent beam from the LED source. This paper discusses light-waves power transmission of a light-emitting diode in a short-range distance. The transmitter consists of a microcontroller-based Arduino and LED. On the other part, the receiver uses the microcontroller and photodiode. The considered modulation is on-off keying (OOK) intended for the application of the IEEE 802.15.7 standard of specification PHY I for indoor communication. This experiment aims to measure the current and voltage received at photodiode from LED. In general, the result shows that the white LED can provide the highest received power than red, green, and blue. The received power decrease as the distance increase. The power degradation insight is useful for further a VLC system implementation. [ABSTRACT FROM AUTHOR]

Most agricultural land is perfectly suited for photovoltaic production, resulting in an increased competition between agriculture and photovoltaic plants for land. Therefore, it is highly important to find solutions that allow the compatibility of agriculture and electricity production. A specific PV panel called Eclipse has been developed and tested since 2005 in order to reach these goals. This panel is designed to increase light transmission to the crops in winter when irradiation is low, and to favor electricity production in summer when irradiation is high. Fresnel lenses are used to achieve this without any moving parts in the panels. The Eclipse panels were tested in two sites in Italy and Spain with successful results on various crops. A new version is now designed using bifacial PV panels and replacing the Fresnel lenses with metallic reflectors, achieving more effective and lower costs. [ABSTRACT FROM AUTHOR]

The paper discusses the effect of multi-walled carbon nanotubes (MWCNTs) modified by electron beams of different intensities on the electro-optical characteristics of polymer-dispersed nematic liquid crystals. It is demonstrated that the electron-beam irradiation of MWCNTs improves the compatibility of tubes and polymer-liquid crystals dispersion, increases the steadiness of suspensions based on them. In turn it results in the reduction of the threshold voltage and response times of the composite to the electric impulse, as well as increasing the light transmission. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) layers were grown on glass substrates by Successive Ion Layer Adsorption and Reaction (SILAR) method using 0.1M zinc acetate in distilled water as cationic solution. The obtained layers were dried and some of the samples are annealed at 450°C for a holding temperature of 2 hours. The X-ray diffraction analysis revealed that the samples are ZnO with hexagonal wurtzite structure. The lattice parameters were calculated and are very close to the standard values. The annealing has changed the preferential orientation of the layer.The Infrared (IR) studies suggested that the Zn-O stretching happens at around 468 cm−1 for both samples.. The samples were analyzed using UV- Visible spectroscopy. It is noted that the optical transmission decreases with annealing. Maximum transmission was found to be 6% at around 850 nm. To identify the near band edge and defect related emission properties of the samples, the Photo Luminescence (PL) spectroscopy is employed. The as deposited sample showed a broader luminescence spectrum owing to its defects and poor crystallanity, while the annealed sample has a well-defined peak centered around 388nm owing to near band edge emission. A small peak is also shown by the same sample around 579nm, which may be defect related one. The surface irregularities and non uniform crystallisation over the surface of the layers has been observed in Scanning Electron Micrograph images and has been again confirmed in Atomic Force Microscopy (AFM) characterisation. This surface roughness could explain the poor transmission of the samples. [ABSTRACT FROM AUTHOR]

Temperature dependent studies of optical transmission profiles of CaF2 crystals in the range 12–300 K are performed using vacuum ultraviolet (VUV) synchrotron radiation. The observed spectral profiles near the transmission edgeare fitted using the universal Urbach tail expression modified appropriately to incorporate the effects of residual gases present in high vacuum (10-6 mbar) systems. Satisfactory fit of the experimental data is obtained by including fitting parameters representing scattering and absorption by deposited layers, predominantly due to water. Details of the experimental setup, results and analysis of the data are discussed. [ABSTRACT FROM AUTHOR]

In the present study optical transmission spectra were recorded within the spectral range from 300 nm to 900 nm for pristine and 100 MeV Ag swift heavy ion irradiated amorphous Ge23Se62As15 thin films with mean coordination number 2.61 for six different fluences (3x1010 ions/cm2, 1x1011 ions/cm2, 3x1011 ions/cm2, 1x1012 ions/cm2, 3x1012 ions/cm2, and 1x1013 ions/cm2). The absorption coefficient calculated by using Lambert-Beer law. The optical band gap is calculated by Tauc's method, which based on absorption coefficient using non-direct transition for chalcogenide semiconductors. The static refractive index is calculated by using Dimitrov-Sakka theoretical model. Reduction in optical band gap and increment in linear refractive index till fluence 3x1012 ions/cm2 is understood using Raman measurement to utilize in optical applications. [ABSTRACT FROM AUTHOR]

We have studied the structural and optical properties of Ni implanted NiO thin films deposited on quartz substrate by electron beam evaporation method at room temperature for different fluences. The structural and optical properties of pristine and implanted NiO thin films were investigated using X-ray diffraction (XRD) and ultraviolet-visible spectrometer respectively. We observed decrease in crystallinity and an induced stress for implantation at low fluence whereas there is relaxation and improvement incrystallinity at high fluence. However, the optical transmission and band gap decreases monotonically with the increase of implantation fluences. [ABSTRACT FROM AUTHOR]

IR transmittingmaterials are required for remote detection of many biological molecules like water, ozone and carbon dioxide as their vibrational absorption bands are between 3-5 and 8-12 µm. Te based chalcogenide glasses having low phonon energy and high refractive index transmit the infrared light from 0.8 µm to 30 µm. Ge-Se-Te glasses prepared by melt quenching method are found to transmit IR light upto 25 µm. These glasses transmit 75 % of the IR light. The glass forming ability and thermal stability of these glasses are high and are difficult to crystallize. The ease of glass formation along with the transmission of IR light over a wide wavelength range indicate that they are potential materials for making IR lenses and drawing optical fibers for IR sensing and spectroscopic applications. [ABSTRACT FROM AUTHOR]

Extraordinary optical transmission was observed in metal films with periodic arrays of subwavelength holes and was related with the excitation of surface electromagnetic modes in the metal film. Here we demonstrate theoretically the realization of the extraordinary phonon transmission, which was predicted recently. We model the layered nanostructure of Ge atoms embedded in Si lattice, which contains a monolayer periodically filled with Ge and Si atoms, symmetrically encapsulated by the atomic-scale layers fully filled with Ge atoms. Such layered nanostructure demonstrates narrow transmission peak in THz frequency range on very low transmission background. The extraordinary phonon transmission occurs through the hidden lattice-wave nanochannels, which are provided by the host Si atoms embedded in the layer of defect Ge atoms which act as effective heavy isotopes in a diamond Si lattice. The encapsulated light Si atoms provide the narrow atomic vibrational eigenmode on almost zero vibrational background of surrounding heavy isotopes through which the resonance quantum phonon tunneling occurs. [ABSTRACT FROM AUTHOR]

The analysis of mechanical performance of a rotating shaft has been commonly measured with strain gauges attached with slip ring or telemetry. Nevertheless, strain gauges are bulky for its size which provides limited number of installations when load distribution at smaller dimensional gap is very crucial. Optical Fibre Bragg Grating (FBG) sensor becomes the substitute and more conventional method when it comes to measuring strain. Its size makes it possible to analyze strain in smaller gaps and unlike electrical sensors, it is also immune to electromagnetic interference. In this paper, a study of mechanical performance of the rotating shaft is done by using FBG sensors and rotary optical coupler, which allows transmission of light from the Amplified Spontaneous Emission (ASE) Source to the FBG sensor. In the earlier studies, there is a pre-evaluation of sensitivity of FBG sensors through the study of strain gauge. Although the general bare FBG has 1.2 pm/με,, the current sensitivity is 0.712 pm/με, The result comparison of the experiment such as deformation is done by using simulation values obtained through Finite Element Analysis (FEA) using the ANSYS Workbench software. The FEA was meshed with different sizes from 3.5 to 0.55 mm. The convergence graph is illustrated and found that 0.75 mm is adequate to be applied for simulation analysis. The obtained result of experimental stress and strain are compared to simulated stationary shaft to have a percentage error ranging from 20-28.87%. On the other hand, the rotating shaft results are discussed as future works are recommended for better improvements of results. [ABSTRACT FROM AUTHOR]

We manufacture magnetorheological suspensions (MRS) based on silicone oil (SO) and carbonyl iron (CI) particles of different concentrations. The MRS is deposited on a transparent thin film, and light is allowed to pass through the system. We show that in the presence of an external magnetic field of low intensity the light transmission can be controlled for each CI concentration. The observed effect can be used for fabrication of various magnetically controlled optical devices. [ABSTRACT FROM AUTHOR]

SnO2 thin films Electron Beam Evaporation techniques prepared nanocrystalline, these films analyses by XRD, UV-Vis, and AFM. The effect of Annealing temperature shows various phases (structures and morphologies). The optical transmission (T %) in the range (190-1000) nm of films prepared was measured. SnO2 thin films show a direct allowed transition and decreased the energy bandgap from 3.75 eV before annealing to 3.62 eV and 3.27 eV after annealing. Through the results, we found that all studied characteristics were affected by the annealing process. [ABSTRACT FROM AUTHOR]

Visible light communication (VLC) is seen as a complementary technology to the conventional Radio Frequency (RF) technology due to its high bandwidth. Most VLC systems are based on intensity modulation/direct detection scheme where the intensity of the optical carrier is modulated. In this paper, two types of modulation schemes namely On-Off Keying (OOK) and Phase Shift Keying (PSK) are investigated. First, the transmitter and receiver circuit for both types of modulation schemes are constructed. LED with 570 nm wavelength is used as the source at the transmitter and a photodiode is used at the receiver. This study proves that PSK can be used for indoor visible light transmission. Then the performance of both modulation schemes is evaluated in terms of the received voltage versus distance in the presence of background ambience light and also without light. The performance of the unmodulated signal is also included for comparison purposes. It is observed that a longer communication distance can be achieved when PSK modulation is used compared to OOK and unmodulated signal. [ABSTRACT FROM AUTHOR]

The results of studies of the microstructure, phase composition, physical and mechanical properties of coatings of the Zr-Y-O system with a thickness of 3 µm on single-crystal Si substrates produced by pulsed magnetron deposition are presented. The results of the laboratory tests of the impact resistance of the silicon samples with protective coatings of the Zr-Y-O system to shock loads, during the interaction of a stream of Fe microparticles moving at a speed of 5 km / s. are given. According to the data of X-ray and TEM, it was establisheded that the composite coatings of the Zr-Y-O system had a submicrocrystalline columnar structure (dav=46–200 nm) and contain the ZrO2 phase in the monoclinic and tetragonal modifications. The study of the optical properties of the samples has shown that the coefficient of light transmission for these coatings varies from 70 to 80% in the wavelength range of 400–800 nm. It has been found that the application of the protective coatings of the Zr-Y-O system with a thickness of 3 µm on the surface of the silicon samples leads to increasing in their microhardness from 14 to 19 GPa. Under laboratory conditions, shock tests have shown that the application of these protective coatings of the Zr-Y-O system allow suppressing the processes of erosion in the latter. This is due to the prevention of the formation of small craters, whose size does not exceed 30 µm, as well as due to a considerable decrease in the number of the craters with size from 30 to 50µm. [ABSTRACT FROM AUTHOR]

ZnSe nanostructured thin films are found to be potential candidates in various optoelectronic applications. They find applications in LEDs, buffer layer of photovoltaic cell etc. The samples were fabricated by a cost effective modified chemical route namely photo enhanced chemical deposition technique. The deposition of nanostructured ZnSe thin films took place from aqueous alkaline medium. The deposition bath at room temperature was illuminated by a UV lamp irradiating at 355 nm. Deposition solution contained zinc sulphate, sodium sulphite, sodium selenosulphate, hydrazine hydrate and triethanol ammine (TEA). The films were uniform and highly adherent. The films were deposited on soda lime glass substrate with various concentrations of ethanol in the deposition bath. The resulting samples were annealed at 373 K for 30 minutes. The deposited films were characterised by various techniques like XRD, UV-VIS-NIR spectrophotometer, SEM etc. The films were found to be polycrystalline in nature with hexagonal structures and addition of ethanol in the bath resulted in face centered cubic structure. The presence of ethanol in the bath introduced changes in structural, optical, and morphological properties of the thin films. The optical transmission of all the samples were above 70% in the visible region and almost uniform. The optical band gap found to decrease with increase in ethanol concentration from 2.74 eV to 2.52 eV whereas the grain size found to increase. The SEM images showed a porous structure which changed to nano flake like structure on the addition of ethanol in to the deposition bath. [ABSTRACT FROM AUTHOR]

Indium oxide (In2O3) thin film of 250 nm of thickness has been synthesized on glass substrates of 300 oC by pulse laser deposition technique. Nd-YAG laser (10 ns, 6 Hz and 140 mJ) has been used for the deposition. The structural properties of In2O3 thin film have been examined by x-ray diffraction (XRD). Polycrystalline structure with preferred plane of In2O3 (222) of the cubic phase and crystallite size of 19.8 nm have been obtained from XRD analysis. The morphological surface properties have been studied using atomic force microscopy (AFM). AFM image shows a homogeneous film and spherical shaped grain of size of 69.9 nm. The (Ra) and (Rq) of In2O3 film have been measured to be 0.413 nm and 0.484nm respectively. The optical properties of the film have been achieved by UV spectroscopy. UV measurements of In2O3 thin film give an indication of a good optical transmission in visible and near infrared regions with an average transmittance over than 90%. The calculated band gap energy value of In2O3 film is 3.6 eV. [ABSTRACT FROM AUTHOR]

In this paper, TiO2 nano-films were deposited by RF magnetron sputtering using a TiO2ceramic target of pure Ti of 3" diameter and 0.250" thickness with a purity of 99.99%, onto heated glass substrates in a temperature range of 200 to 450°C. This study determines the temperature effect on the structural, optical and morphological properties of TiO2 nano-films. For this, we used X-ray diffraction for structural characterization and optical transmission spectroscopy UV-Visible for optical characterization and atomic force microscopy (AFM) for morphological characterization of the films produced. The (101), (400), (112), (200), (105), (211), (213), (204) peaks of the anatase structure and the (210), (102), (-112) (710) peaks of the monoclinic structure are observed. In addition, the peaks are sharp and intense which implies a good crystalline structure. Otherwise, the films optical gap variation is proportional to the temperature variation from 3,9eV to 3,92 eV for T=200°C and T=450°C, respectively. The surface roughness of TiO2 nano-films range from 1,031nm to 4,665nm. [ABSTRACT FROM AUTHOR]

Nanocrystalline copper selenide (Cu2Se) has been synthesized by the hydrothermal co-reduction method. X-ray diffraction studies reveal the crystalline nature of its single phase. TEM images of the as-prepared sample show the formation of nanoparticles of diameter 10–35 nm. Open aperture z-scan measurements carried out using ultrafast (100 fs) laser pulses at 800 nm show that the sample exhibits saturable absorption at relatively lower input fluences and reverse saturable absorption at relatively high input fluences, indicating its versatile use as a photonic material. [ABSTRACT FROM AUTHOR]

Organic single crystal of p-Toluidinium oxalate (PTO) was grown by slow evaporation technique. Single crystal X-ray diffraction analysis reveals that PTO crystal belongs to monoclinic system with space group C2/c. The optical transmission study revealed the transparency of the grown crystal in the entire visible region and the cut off wavelength was found to be 222 nm. Photoluminescence spectral studies revealed the photon excitation. The presence of various functional groups in the grown crystal was identified from FTIR spectral analysis. The nonlinear refractive index (n2) and nonlinear absorption coefficient (β) and third order nonlinear optical susceptibility were evaluated by Z-scan technique. [ABSTRACT FROM AUTHOR]

This work explores the correlations of modern physics and the (Orthodox Christian) theology, through the analysis of space and light. In modern physics, the space we think we occupy is nothing but constant repulsion of point-like particles. "Space" tends to concepts such as separation - demarcation, distance - range, space - dimension. While light with bosonic nature tends to gather and unite instead of separate, it "lives" out of time and space instead of decay and isolation. On the other hand, Theology teaches that selfishness is what separates us, separate will that holds us in distance, sin that depart us from our original destination. The proposition: co-space, co-fit, co-placement (forgiveness, “sin-horesi” in Greek) and love that is union, coupling, and leads to salvation (hold in one unit, “sotiria” in Greek), which tends to keep man as one unit through reunion with the Creator. In this sense, the characteristics of light in physics described above are correlated. [ABSTRACT FROM AUTHOR]

A small solar cell was assembled with various textured surface covers and investigated for the effects of light transmission and surface temperature. Four textured covers made of plactic were studied, namely plain surface, inverted pyramids, light grooved Fresnel lens, round grooved Fresnel lens and two different exposed areas without any cover for benchmarking purposes, creating six test modules. Measurements of light transmission in terms of short circuit currents, Isc, were collected as a function of angle of incidence using a solar simulator. A thermocouple was also used to measure the temperature of the solar cell in order to evaluate the effect of textured surface covers on the solar cell temperature. Results show a decrease in short circuit current, Isc of up to 8.26% for inverted pyramids in comparison to the flat surface cover. In addition, the light gain, Isc, decreases at higher angles of incidence. Nonetheless, it was found that the inverted pyramids surface has a reasonable cooling effect with 2 °C of temperature drop. The decreased temperature will potentially increase the power output as well as efficiency of the solar cell with a textured cover. [ABSTRACT FROM AUTHOR]

A method for measuring angles that characterize the properties of the superhydrophobic coatings was developed. Hydrophobic coatings were prepared using nanosized silica and effect of the sample composition on wetting angle and light transmission were determined. [ABSTRACT FROM AUTHOR]

The soiling accumulation over the surfaces of photovoltaic (PV) and concentrated photovoltaics (CPV) modules decreases the annual energy production. In this work, an anti-soiling coating for PV glasses and lenses to avoid or decrease the soiling deposition onto PV and CPV modules is presented. Three different anti-soiling coatings are deposited over the surface of real lenses and glasses. The anti-soiling performance is tested by measuring the surface free energy of the uncoated and coated samples. The results show that the plasma treatment of the samples before anti-soiling application increases the performance of the coating. Regarding the effect of curing process, the results indicate that the curing process is not significant to increase the anti-soiling performance. Among the three formulations tested, F1 is the best one for glass material and F3 is the best one for poly methyl methacrylate (PMMA) lenses. In the near future, in order to detect any adverse effect in the light transmission in the long-term, the samples will be tested in the lab with accelerated aging tests to verify its durability and reliability in time. [ABSTRACT FROM AUTHOR]

Bilayer thin films of Bi/Sb2S3 and Ag/Sb2S3 were prepared by thermal evaporation method in high vacuum condition. X-ray diffraction study (XRD) revealed the amorphous nature of all the films as no sharp peak was found. SEM study indicated the smooth surface for the three films. The elemental presence was confirmed from EDX study. The optical transmission was studied by FTIR spectroscopy in the range 500-1200 nm. The transmission % is found to be decreased and absorption coefficient increased with the deposition of 10 nm Bi and Ag layer onto Sb2S3 film. The optical band gap calculated by Tauc's relation shows anincrease in band gap from 1.54 eV (Sb2S3) to 1.60 eV (Bi/Sb2S3) and 1.64 eV(Ag/Sb2S3)with Bi and Ag deposition onto Sb2S3 layer. This increase in optical band gap is discussed in terms of defect states and degree of disorderness. [ABSTRACT FROM AUTHOR]

The present paper emphasizes on the structural and optical properties change in thermally evaporated Bi doped Ge30Se70 thin film. Thin films of Ge30Se70 and Ge30Se60Bi10 were prepared by thermal evaporation technique from the bulk material under high vacuum condition. X-ray diffraction study (XRD) revealed the amorphous nature of both the films as no sharp peak was found. Scanning electron microscopy (SEM) study indicated the smooth surface for both the films. The elemental presence was confirmed from Energy Dispersive X-ray spectroscopy (EDXS). The optical transmission was recorded by Fourier Transform Infra Red (FTIR) spectroscopy in the range 500-1100 nm. The optical band gap calculated by Tauc's relation shows a large decrease in band gap from 1.67 eV (Ge30Se70) to 1.05 eV (Ge30Se60Bi10) with Bi incorporation. This decrease in band gap is discussed in terms of defect states and degree of disorderness in the film. After incorporation of Bi, the increase in width of localized states in the band gap region reduces the optical band gap. [ABSTRACT FROM AUTHOR]

Passivating contacts are considered as a possibility to enhance silicon based PV performance due to lower interface recombination rates of charge carriers. Most of the investigation on metal oxide based contacts so far was done in laboratory scale. Mass production requires the scale-up of the processes. This contribution reports on first deposition experiments of MoOx hole selective contacts by industrial size reactive magnetron sputtering and thermal evaporation. Reactive sputtering was carried out on a vertical inline tool equipped with a rotatable target of 1 m length. Thermal evaporation was conducted with a linear evaporation source of 46 cm length. Films were deposited on solar cell precursors in order to estimate charge carrier selectivity and band bending induced into the c-Si wafer by the MoOx based hole contact. First results show that the selectivity, band bending, and optical transmission of reactively sputtered MoOx films depend on the working point of the reactive sputter process. However, the selectivity still is far from what was reached in smallscale evaporation experiments. Films deposited with the industrial linear evaporation source show much better selective properties even comparable to lab-scale evaporation. Based on these results there seems to be a high potential to transfer the small scale laboratory evaporation process to larger areas in dynamic deposition, but further work is needed to tailor the properties of the sputter deposited MoOx. [ABSTRACT FROM AUTHOR]

Cr doped CdO thin films were deposited on mica substrates by reactive DC magnetron sputtering technique by varying substrate temperature from room temperature (RT) to 350 °C. X-ray diffraction studies reveal that the films exhibit cubic structure with highly oriented in the (2 0 0) direction. The surface morphology of the films was observed by field emission scanning electron microscopy. The optical transmittance of the films increased from 70 to 82% with the increase of substrate temperature. The electrical resistivity of the films was measured by four-probe method. The film deposited at the substrate temperature of 350 °C shows the highest optical transmittance of 82% and is attributed to less scattering effects, structural homogeneity, and better crystallinity. The optical constants (n and k) and optical band gap (Eg) of the films were determined from the optical transmission spectra. [ABSTRACT FROM AUTHOR]

Thin films of SnS have been obtained from Sn and S powders which were mixed up using ball mill technique with and without evaporating additional sulphur prior to annealing at 523K. The obtained samples were taken for structural, optical, chemical and morphological studies. The X-ray diffraction reveals the formation of SnS phase on annealing in vacuum having S/Sn ratio of 0.67 obtained from EDAX. This deficit in ‘S’ is removed by supplementing additional ‘S’ of 200nm prior to annealing which results in the S/Sn ratio of 1.01. The optical transmission recorded from spectrophotometer used to study different optical parameters. Morphological results corroborate well with the XRD, EDAX and optical study. The obtained stoichiometric films were also tested for Ag/p-SnS Schottky diodes on In coated glass substrates using current voltage measurements. [ABSTRACT FROM AUTHOR]

Structural and optical properties of Titanium Oxide (TiO2) thin films deposited by RF magnetron sputtering with variation in argon (Ar) flow rate (20-40 sccm) have been studied. The film structure, optical transmission and band gap was studied using Raman spectroscopy, X-ray diffraction (XRD) and UV-Vis-NIR spectroscopy. In the as-deposited films, mixed phase i.e. rutile and anatase phase of TiO2 was obtained. Effect of annealing on the deposited film was also studied. Phase transformation from mixed phase in as deposited films to pure anatase phase of TiO2 after annealing at 500 °C for 2 hours was observed. Band gap of the as deposited film at Ar flow rate of 35 sccm is around 3.01eV and for the annealed film it is 2.92eV. The optical transmission in the visible range for as deposited film at Ar flow rate of 35 sccm is between 70-90% and for annealed film it is 64-85%. [ABSTRACT FROM AUTHOR]

Highly conducting and transparent FTO (flourine doped tin Oxide) thin films were grown on the glass substrates using a low cost spray pyrolysis technique. The films were characterized for their structural, morphological and optical studies using XRD, SEM and UV-Vis spectroscopy. XRD studies show that the FTO films crystallize in Tetragonal cassiterite structure. Morphological analysis using SEM show that the films are uniformly covered with spherical grains albeit high in surface roughness. The average optical transmission greater than 80% in the visible region along with the appearance of interference fringes in the transmission curves confirms the high quality of the films. Electrical studies show that the films exhibit sheet resistance below 10 Ω ϒ-1. [ABSTRACT FROM AUTHOR]

Nanocrystalline iron selenide (FeSe2) has been synthesized by the hydrothermal co-reduction method. X-ray diffraction studies reveal the crystalline nature of their single phase. TEM images of the as-prepared samples show the formation of nanorods with lengths of 40-75 nm and diameters of 10-20 nm respectively. The energy band gap calculated using the Tauc plot is found to be 1.39 eV. Open aperture z-scan measurements carried out using ultrafast (100 fs) laser pulses at 800 nm show that the sample exhibits saturable absorption at relatively lower input fluences and reverse saturable absorption at relatively high input fluences, indicating its versatile use as a photonic material. [ABSTRACT FROM AUTHOR]