An investigation of the polarization dependence of a temperature sensor based on an optical microfiber coupler

The dependence on polarization of the performance of a microfiber coupler based temperature sensor is experimentally investigated. The optical microfiber coupler based temperature sensor has a diameter circa 2µm and can sense temperature in the range from 100°C to 1000°C, with an average sensitivity of 18.9pm/°C. It is shown that different polarization states of the input signal have a significant influence on the proposed temperature sensing accuracy, with a estimated peak error of 63°C at 1000°C

On optimal recovering high order partial derivatives of bivariate functions

The problem of recovering partial derivatives of high orders of bivariate functions with finite smoothness is studied. Based on the truncation method, a numerical differentiation algorithm was constructed, which is optimal by the order, both in the sense of accuracy and in the sense of the amount of Galerkin information involved. Numerical demonstrations are provided to illustrate that the proposed method can be implemented successfully

Chalcogenide microsphere fabricated from fibre taper-drawn using resistive heating

Over the last decade extreme interest for microsphere resonators has increased rapidly due to their very high quality Q factors, the ease with which they can be manufactured and their versatility in terms of materials and dopants for plenty of passive and active devices. Furthermore, microsphere resonators have the potential to add significant functionality to planar lightwave circuits when coupled to waveguides where they can provide wavelength filtering, delay and low-power switching, and laser functions [1].Recently, chalcogenides are rapidly establishing themselves technologically superior materials for emerging application in non-volatile memory and high speed switching [2] and have been considered for a range of other optoelectronic technologies. Chalcogenide glasses offer a wide wealth of active properties, an exceptionally high nonlinearity, photosensitivity, the ability to be doped with active elements including lanthanides and transitional metals and are able to form detectors, lasers and amplifiers and offer semiconductor, optical, acousto-optic, superconducting and opto-mechanical properties. Unlike any other optical material, they have been formed in to a multitude of form: such as optical fibres, thin films, bulk optical components, microsphere resonators, metamaterials and nanoparticles, patterned by CMOS compatible processing at the sub micron scale. To date, most studies on microsphere resonators have utilized silica microspheres fabricated by melting the tip of an optical fibre with the resulting stem attached to the microsphere used as a tool to place the sphere in the required location while characterizing the microsphere. In this paper high quality chalcogenide (As2S3) microspheres with diameters down to 74 µm are directly fabricated from the taper-drawn using a resistive heating process. A reasonable high quality factor greater than 105 near the wavelength of 1550 nm is demonstrated with an efficient coupling using a fibre taper with a diameter of 2 µm

High-Q bismuth silicate nonlinear glass microsphere resonators

The fabrication and characterization of a bismuth-silicate glass microsphere resonator has been demonstrated. At wavelengths near 1550 nm, high-modes can be efficiently excited in a 179 µm diameter bismuth-silicate glass microsphere via evanescent coupling using a tapered silica fiber with a waist diameter of circa 2 µm. Resonances with Q-factors as high as were observed. The dependence of the spectral response on variations in the input power level was studied in detail to gain an insight into power-dependent thermal resonance shifts. Because of their high nonlinearity and high- factors, bismuth-silicate glass microspheres offer the potential for robustly assembled fully integrated all-optical switching devices

Polystyrene-based nanocomposites with different fillers: fabrication and mechanical properties

The paper presents a comprehensive analysis of elastic properties of polystyrene-based nanocomposites filled with different types of inclusions: small spherical particles (SiO2 and Al2O3), alumosilicates (montmorillonite, halloysite natural tubules and Mica) and carbon nanofillers (carbon black and multi-walled carbon nanotubes). Composites were fabricated by melt technology. The analysis of composite melts showed that the introduction of Montmorillonite, Multi-walled carbon nanotubes, and Al2O3 particles provided an increase in melt viscosity by an average of 2 to 5 orders of magnitude over the pure polystyrene. Block samples of composites with different filler concentrations were prepared, and their linear and nonlinear elastic properties were studied. The introduction of more rigid particles led to a more profound increase in the elastic modulus of the composite, with the highest rise of about 80% obtained with carbon fillers. Carbon black particles provided also an enhanced strength at break of about 20% higher than that of pure polystyrene. The nonlinear elastic moduli of composites were shown to be more sensitive to addition of filler particles to the polymer matrix than the linear ones. The nonlinearity coefficient $\beta$ comprising the combination of linear and nonlinear elastic moduli of a material demonstrated considerable changes correlating with changes of the Young's modulus. The absolute value of $\beta$ showed rise in 1.5-1.6 times in the CB- and HNT-containing composites as compared to that of pure PS. The changes in nonlinear elasticity of fabricated composites were compared with measurements of the parameters of bulk nonlinear strain waves in them. Variations of wave velocity and decay decrement correlated with observed enhancement of materials nonlinearity

МЕТОДИ ВДОСКОНАЛЕННЯ ВЗАЄМОДІЇ СУБ’ЄКТІВ ЕКОНОМІЧНОЇ СИСТЕМИ ВОДОКОРИСТУВАННЯ

This article analyses the system of water resources users due to the available parameters. The problems of the cooperation between the elements of the system and influence of the deficiencies in their coworkon the rational resources use system were investigated. Methods to improve the indicators of rational water resources use by using the mechanisms and their combinations for the better users cooperation have been proposed.Проанализирована система субъектов водопользования по доступным параметрам. Исследована проблематика взаимодействия субъектов и влияние недостатков в их взаимодействии на систему рационального водопользования. Предложены методы учета доступных механизмов и их комбинаций по поводу взаимодействия субъектов системы для улучшения показателей рационального водопользования.Проаналізовано систему суб’єктів водокористування за доступними параметрами. Досліджено проблематику взаємодії суб’єктів та вплив недоліків у взаємодії водокористувачів на систему раціонального водокористування. Запропоновані методи врахування доступних механізмів та їх комбінацій щодо взаємодії суб’єктів системи для покращання показників раціонального водокористування

ЕКОНОМІЧНІ ОСНОВИ ВПРОВАДЖЕННЯ ПОВТОРНОГО ВОДОКОРИСТУВАННЯ ВІДПОВІДНО ДО КОНЦЕПЦІЇ «ВІРТУАЛЬНОЇ» ВОДИ ТА «ВОДНОГО СЛІДУ»

This article gives a characteristic of the concept of the secondary water resources use due to industrial needs. The problematic of involvement ofwater for the secondary use is being described. The methods of therationalization of water resources use were proposed, basing on theconcept of virtual water and water step as a tool for defining and analyzingthe current situation in the regional water resources use.В данной статье охарактеризована концепция повторного использования воды в промышленных нуждах, описана проблематика внедренияводы для повторного водопользования. Предложены методы рационализации водопользования на основе концепции виртуальной воды и водного следа как инструмента определения и анализа текущей ситуации водопользования в регионе.Проаналізовано концепцію повторного використання води у промислових потребах. Досліджено проблематику залучення води для повторного використання. Запропоновані методи раціоналізації водокористування на основі концепції «віртуальної» води та водного сліду як інструменту визначення та аналізу поточної ситуації водокористування у регіоні

A Photonic Crystal Fiber Based Polarimetric Sensor for Cure Monitoring of Magneto-Rheological Smart Composite Material

A buffer stripped high birefringent photonic crystal fibre based polarimetric sensor is developed for monitoring the curing process of magnetorheological elastomer (MRE) smart composite material. Using the developed sensor, different phases of the MRE curing process are clearly visible from the phase shift variation of the embedded polarisation maintaining photonic crystal fibre (PM-PCF) sensor. During the curing process, the buffer stripped PM-PCF exhibits a stress/strain induced phase shift variation from 0 to 1.98 rad. This is a significantly large phase change, which can be used to very clearly identify the different stages in the curing process. For comparison, a fibre Bragg grating sensor is also used for monitoring the internal strain during the curing process and its response does not allow one to reliably distinguish all the curing stages. The present investigation offers a simple non-destructive method to monitor the curing process of MRE smart composite material

High resolution spectroscopy of thulium atoms implanted in solid noble gas crystals

Optically active defects in solid-state systems have many applications in quantum information and sensing. However, unlike free atoms, which have fixed optical transition frequencies, the inhomogeneous broadening of the transitions in solid-state environments limit their use as identical scatterers for such applications. Here we show that crystals of argon and neon prepared in a closed-cycle cryostat doped with thulium atoms at cryogenic temperatures are an exception. High resolution absorption and emission spectroscopy show that the 1140 nm magnetic dipole transition is split into multiple components. The origin of this splitting is likely a combination of different classes of trapping sites, crystal field effects within each site, and hyperfine interactions. The individual lines have ensemble widths as small as 0.6 GHz, which temperature dependence and pump-probe spectroscopy indicate is likely a homogeneous effect, suggesting inhomogeneity is well below the GHz scale