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Due to the increase in water pollution (Bacteria, viruses, heavy metals, salts, etc..), it became necessary to search for new technologies and develop their performance in detecting and sensing levels of pollution for the purpose of treating them. Here in this research paper, simulation, through the COMSOL software was performed to develop the performance of the optical fiber pollution sensor through the test of changing the parameters of the optical fiber structure such as the cladding diameter with different thicknesses and doping of its material, which was of silicon with germanium with different concentrations and studying the amount of better thickness and the best concentration of the impurity to obtain the best performance of the optical fiber sensor In sensing water pollution with sodium chloride salt (for example). A single mode optical fiber with different diameters had been designed as a pollution sensor. These sensors were doped with Germanium with different concentrations in cladding region. From the obtained results it had been found that the sensors with less diameter of nanometer range were more sensitive to refractive index change of applied analyte. The higher sensitivity was obtained with fiber diameter circa 6.5 µm. Also it had been found that as Germanium concentration increase (with fixed cladding thickness) the sensor were more sensitive to the change of analyte refractive index, the best results were obtained with concentration 0.19 wt%. These sensors could be very useful in field of water pollution detection. [ABSTRACT FROM AUTHOR]

In this work, physical and mathematical models of powder transportation by gas during laser cladding are discussed. The main attention is paid to modeling the interaction of powder particles and nozzle walls. The results of numerical simulation and experimental data are compared. [ABSTRACT FROM AUTHOR]

A novel composite light-weight microporous cladding panel with matched connection detailing is developed. Numerical simulation on the experiment is conducted by ABAQUS. The accuracy and rationality of the finite element model is verified by comparison between the simulation and the experiment results. It is also indicated that the novel composite cladding panel is of desirable bearing capacity, stiffness and deformability under out-of-plane load. [ABSTRACT FROM AUTHOR]

In the present work, a combined method is considered for the production of a metal-matrix composite coating based on Ni and B4C. The coating is created by consistently applied methods: cold spray and laser cladding. The conditions of obtaining cermet layers are investigated depending on the parameters of laser cladding and cold spray. It is shown that the laser track structure significantly changes in accordance to the size of ceramic particles ranging 3-75 µm and its concentration. It is shown that the most perspective layers for additive manufacturing could be obtain from cold spray coatings with ceramic concentrations more than 50% by weight treated in the heat-conductivity laser mode. [ABSTRACT FROM AUTHOR]

The work is devoted to the numerical and experimental study of surface plasmon resonance in a bent singlemode optical fiber with metalized cladding. It was shown that with a proper combination of metal film thickness and bend radius one can achieve coupling between fundamental and surface plasmon modes through an intermediary of whispering gallery mode supported by the bent fiber's optical cladding. This brings about a dip in the transmission spectrum of the fiber at the resonant wavelength which depends strongly on the external medium refractive index, so that refractometric measurements can be performed with a sensitivity of ~5 μm/RIU and resolution ~4·10-6. [ABSTRACT FROM AUTHOR]

Integrated optics is one of the most intensively investigated fields when working on alternative methods to overcome the disadvantages of integrated electronics. Besides inorganic active optical crystals, dyes and polymers, molecules of biological origin with suitable nonlinear optical properties can also find applications in integrated optical - biophotonic - devices. The state-of-the-art photonic integration technology is ready to provide the passive elements of integrated optical circuits. The bottle-neck in integrated optics is to find a proper nonlinear optical material that is supposed to be the cladding medium in waveguide-based photonic applications, performing light-controlled active functions. Based on our earlier results, here we present the experimental demonstration of subpicosecond photonic switching with an alternative approach, where the active role is performed by a biological material, the chromoprotein bacteriorhodopsin. Moreover, measurements of the light-induced refractive index change performed on a dried film of the Photoactive Yellow Protein are also presented. Our findings show that these photochromic pigments can be promising candidates as active nonlinear optical materials for all-optical data processing in future biophotonic applications. These results may serve as a basis for the future realization of protein-based integrated optical devices that can eventually lead to a conceptual revolution in the development of telecommunication technologies. [ABSTRACT FROM AUTHOR]

The paper presents the experimental investigation of the creation of complex composition corrosion-resistant coatings with low abrasive wear which are used in oil industry, by the method of laser cladding additive technology. Availability of the additive laser cladding of the complex composition corrosion-resistant coatings with a strengthening phase is shown. Optimal conditions for the cladding layers creation regarding the laser radiation parameters and radiation direction are found. The changes in micro-hardness, micro-structure and structure-phase components are established against the strengthening phase content in the upper clad layer. Different content of the strengthening phase in the upper layer from 10% to 30% does not change the micro-hardness of the upper layer and is on the average 700 HV. The laser irradiation of the powder mixture containing the strengthening phase results in the partial rupture of the WC strengthening phase. Hence the chemical interaction of the tungsten-cobalt powder mixture and stainless steel occurs and results in complex carbide formation. [ABSTRACT FROM AUTHOR]

The microstructure, hardness property and wear resistance of WC, Ni-Cr and Fe powders deposited by laser cladding at varying processing parameters were investigated. The results of the present study revealed the prospects of multilayer cladding of R6M5 high-speed tool steel (analog of M2 steel (USA) and HS6-5-2 steel (EU)) onto low-alloy steel with the use of a laser beam. Controlling thermal cycles of laser cladding, it is possible to obtain a clad coating made of high-speed steel having the structure of high-alloy austenite-martensite mixture with disperse inclusions of carbides up to 10 mm thick, i.e., it is actually possible to create bimetal structures. The wear resistance of the laser-clad self-fluxing PG-10N-01 (Ni-Cr-B-Si-C) alloy increases by a factor of 5 due to addi-tional hardening by cast tungsten carbide (WC) with spherical particles. As a result, it becomes higher than the wear resistance of high-speed steel by more than a factor of 3. [ABSTRACT FROM AUTHOR]

The fabrication and study of a cladding modified fiber optic intrinsic urea biosensor based on evanescent wave absorbance has been presented. The sensor was prepared using cladding modification technique by removing a small portion of cladding of an optical fiber and modifying with an active cladding of porous polyaniline-boric acid (PBA) matrix to immobilize enzyme-urease through cross-linking via glutaraldehyde. The nature of as-synthesized and deposited PBA film on fiber optic sensing element was studied by ultraviolet-visible (UV-vis) spectroscopy and X-ray diffraction (XRD) analysis. The performance of the developed sensor was studied for different urea concentrations in solutions prepared in phosphate buffer. [ABSTRACT FROM AUTHOR]

Long-period gratings is class of fiber gratings, in which the period of the refractive index modulation is such that it satisfies a phase matching condition between the fundamental core mode and forward propagating cladding modes of an optical fiber. Many applications in optical communications and optical fiber sensing have been reported along the last years. In this work we present a simulation tool for determining LPG transmission spectrum and the coupling curve. The simulation tool uses MatLab code. The software produces also estimations of the resonant wavelength displacement due to changes in external parameters like temperature or external refractive index. A simple comparison between the simulation and the experimental result show that exist a good agreement with results obtain. [ABSTRACT FROM AUTHOR]

The design of fiber optic sensor is based on a cladding modification methodology. A fiber-optic chemical sensor is developed by replacing a certain portion of the original cladding with a chemically sensitive material, specifically, calcinated gadolinium oxide (Gd2O3). Both the light absorption co-efficient and refractive index change upon exposure to chemical vapours of volatile organic compounds (VOCs) such as ammonia (NH3), ethanol (CH3CH2OH), and methanol (CH3OH). The spectral characteristics of the sensor were studied for different concentrations ranging from 0-500 ppm. These changes induced the optical intensity modulation of the transmitted optical signal. During interaction between the sensing material and VOCs, the output intensity is taken into account to detect the toxic VOCs present in the environment. This was systematically investigated by X-ray diffractometer (XRD) and SEM. The XRD analysis indicated that the calcinated Gd2O3 was formed in cubic structure with the crystallite size of 13 nm. The Gd2O3 nanorods with thickness ranging from 80 to 120 nm were confirmed from SEM. The ammonia gas response of the Gd2O3 sensor is presented. A model is proposed for understanding the spectral intensity variations. [ABSTRACT FROM AUTHOR]

Microstructured optical fibers (MOFs) have wavelength scale periodic microstructure running along their length. Their core and two-dimensional microstructured cladding might be based on varied geometries and materials, enabling light guidance due to different propagation mechanisms over an extremely large wavelength range, extending to the terahertz (THz) frequency region. As a result, these fibers have revolutionized the optical fiber technology by means of creating new degrees of freedom in the fiber design, fabrication and applicability. We analytically study the modal properties of terahertz microstructured optical fiber (THz MOF), by using our analytical field model, developed for optical waveguides. [ABSTRACT FROM AUTHOR]

When a hole assisted fiber (HAF) curl cord expands and contracts, the polarization direction of the light emitted from it rotates. A curl cord is divided into several sections by fixing it at several points. When the curl cord is flipped at a point within one of these sections, then vibration is observed with the characteristic frequency to the flipped section. The vibration period of a HAF curl cord can be detected by monitoring the light power emitted from the curl cord after passing through a polarizer. We confirmed theoretically and experimentally that the vibration period of the polarization change is proportional to the length of the section including the flipped point, which can be applied to intrusion location. [ABSTRACT FROM AUTHOR]

We propose a leaky channel waveguide for large-mode-area extended single-mode operation. The proposed structure is characterized by specially designed guiding core and multilayer cladding. Waveguide is able to support single-mode operation with mode area as large as 100 μm2. [ABSTRACT FROM AUTHOR]