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1

Numerical simulations of a simple refractive index sensor based on side-hole optical fibres

Dudek Michał, Köllő Kinga K.

Opto-Electronics Review

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2022

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Vol. 30, No. 4

art. no. e143607

EN

In this work the influence of the cavity parameters on optical losses of a simple intensitybased in-line refractive index sensor utilizing a micromachined side-hole fibre was studied by means of numerical simulations. To perform these simulations, the Authors used the finite-difference time-domain method. The proposed sensor setup consists of light source, micromachined optical fibre as a sensor head, and a detector which makes it low-cost and easy to build. The changes of the external refractive index can be, therefore, recovered by direct measurements of the transmitted intensity from which insertion loss values can be calculated. By changing geometry of the cavity micromachined into the side-hole optical fibre, it was possible to determine its influence on the final sensor sensitivity and measurements range. Based on the provided analysis of simulations results, a simple fibre optic sensor can be fabricated mainly for sensing external liquids refractive index for application in biochemistry or healthcare.

2

Pulsed laser deposition of ZnO and MoO3 as reflection prohibitors on photovoltaic cell substrate to enhance the efficiency

Selvan P., Jebaraj D. J. J., Hynes N. R. J.

Journal of Achievements in Materials and Manufacturing Engineering

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2022

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Vol. 113, nr 2

65--71

EN

Purpose: With the ever-growing demand for conventional fuels, the improvement in the efficiency of the photovoltaic system is the need of the hour. Antireflection coatings enhance the availability of solar power by reducing the percentage of light reflected. A new coating has been developed to improve the solar cell's overall efficiency. This study focuses on enhancing the efficiency of the monocrystalline solar cell when a coating of ZnO-MoO3 is applied at a certain thickness. Design/methodology/approach: A layer of ZnO followed by MoO3 is deposited on a Silicon solar cell substrate using a Pulsed Laser Deposition process. Due to the transmissivity d between the two materials, they act as excellent antireflection coating. The layer thickness has been engineered to lie in the maximum absorption spectrum of monocrystalline silicon solar cells, which is between 400 and 800 nanometers. Findings: Based on the calculation of transmissivities for a given layer thickness of coating material, the coating has been done, and the efficiencies of the coated specimen were compared with the uncoated solar cell. The percentage improvement in the electrical efficiency of a single crystalline silicon solar cell with an anti-reflection coating at 1059 W/m2 is about 35.7%. Research limitations/implications: Among the available antireflection coating materials, the combination that provides better efficiency when coated on top of a solar cell is hard to find. Practical implications: This anti-reflection coating could be a better solution to enhance the overall efficiency of the single crystalline silicon solar cell. Originality/value: Although ZnO and MoO3 coatings have been investigated separately for improvement in solar cell efficiency with varying levels of success, the hybrid coating of ZnO/MoO3 with a performance enhancement of 35.7% is a great leap.

3

Refractive index and salinity sensors by gallium-doped zinc oxide thin film coated on side-polished fibers

Tien Chuen-Lin, Mao Hao-Sheng, Mao Tzu-Chi

Optica Applicata

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2021

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Vol. 51, nr 1

23--36

EN

This work presents a high-sensitivity refractive index and salinity sensor by using fiber-optic side-polishing and electron-beam evaporation techniques. Thin film coated on the flat surface of side-polished fibers can generate a lossy mode resonance (LMR) effect. A gallium-doped zinc oxide (GZO) thin film was prepared by an electron-beam evaporation with the ion assisted deposition method. The residual thickness of the side-polished fiber was 76.5 μm, and GZO film thickness of 69 nm was deposited on the flat surface of the side-polished fiber to fabricate LMR-based fiber sensors. The variation in the optical spectrum of LMR-based fiber sensors was measured by different refractive index saline solutions. The LMR wavelength shift is caused by the refractive index change, which is nearly proportional to the salinity. The corresponding sensitivity of the proposed fiber-optic sensor was 3059 nm/RIU (refractive index unit) for the refractive index range of 1.333 to 1.398. To evaluate the sensitivity of LMR salinity sensors, the saline solution salinities of 3.6%, 7.3%, 10.9%, 14.6%, 18.2% and 21.9% were measured in this work. The experimental result shows that the sensitivity of the proposed salinity sensor is 9.94 nm/%.

4

Optical characterization of thin Al2O3 layers deposited by magnetron sputtering technique at industrial conditions for applications in glazing

Dywel Piotr, Skowroński Łukasz

Materials Science Poland

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2020

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Vol. 38, No. 1

108--115

EN

In this study, thin Al2O3 films (11 nm – 82 nm) were deposited by means of a recently developed pulse gas injection magnetron sputtering method and investigated by means of atomic force microscopy, spectroscopic ellipsometry and spectrophotometry. Quite low values of optical constants (1.581 to 1.648 at λ = 550 nm) of the alumina films are directly associated with specific growth conditions (pulse injection of the reactive or reactive + inert gas) in the pulse gas injection magnetron sputtering process. The light transmittance of Al2O3/glass systems (86 % to 90 %) is only a few percent lower than that calculated for glass (93 %).

5

Kryształy fotoniczne nadzieja na nowy, a zarazem przyjazny środowisku materiał do licznych i przyszłościowych zastosowań w papiernictwie i poligrafii

Podsiadło Halina, Zwierzchaczewska Magdalena

Przegląd Papierniczy

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2019

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R. 75, nr 8

510--516

PL

Kryształy fotoniczne wykazują wiele właściwości, nad którymi prowadzone są liczne badania. Dzięki nim możliwe jest świadome sterowanie transmisja światła, a tym samym przemyślana kolorystyka, ponieważ nie jest ona tworzona przez mieszankę addytywna lub subtraktywna, lecz zmiany barw powstają w wyniku obecności fotonicznej przerwy wzbronionej w ich strukturze. Prowadzenie eksperymentów związanych z poznawaniem właściwości kryształów fotonicznych jest bardzo kosztowne. Nie było dotychczas możliwe uzyskanie warunków dla ich masowej produkcji. Można przypuszczać, ze struktura tych kryształów zapewnia nowe podejście do problemów świetlnych. W poligrafii sa używane jako rodzaj zabezpieczenia, ponieważ kryształy fotoniczne są wprowadzane do pigmentów farb drukarskich. Jednak rozważana jest również możliwość tworzenia papieru fotonicznego, który zastąpiłby dotychczasowe metody zadrukowania tradycyjnego papieru. W tym celu stosuje się metodę pęcznienia matrycy polimerowej. To rozwiązanie jest przyjazne dla środowiska, ponieważ aby uzyskać druk wielokolorowy wystarcza roztwory wodne o określonym pH.

EN

The photonic crystals exhibit many properties over which numerous studies are conducted. Thanks to them, it is possible to consciously control the transmission of light, and hence the thoughtful color scheme, because it is not created by an additive or subtractive mix, but the color changes result from the presence of a photonic band gap in their structure. Conducting experiments related to studying the properties of photonic crystals is very expensive. It has not yet been possible to obtain conditions for their mass production. It can be assumed that the structure of these crystals provides a new approach to light problems. In polygraphy they are used as a kind of security, because photonic crystals are introduced into printing ink pigments. However, it is also considered the possibility of creating photonic paper, which would replace the existing methods of printing traditional paper. For this purpose, the swelling method of the polymer matrix is u sed. This solution is environmentally friendly, because to obtain multi-color printing, water solutions with a certain pH will suffice.

6

Influence of modifiers on thermal and optical properties of TeO2–P2O5–ZnO–PbF2 glasses

Reben Manuela, Burtan-Gwizdała Bożena, Cisowski Jan, Grelowska Iwona, El Sayed Yousef, Bukalska Julita

Optica Applicata

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2019

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Vol. 49, nr 3

403--413

EN

A series of fluorotellurite glasses based on 70TeO2–5MxOy–10P2O5–10ZnO–5PbF2 in mol%, where MxOy = (WO3, Nb2O5) doped with 2400 ppm of Er2O3 have been prepared by the conventional melt quenching method. The influence of modifiers on thermal and optical properties of glasses has been analyzed. Thermal characteristics of glasses like the glass transition temperature Tg, the temperature for the crystallization onset Tx, the maximum crystallization temperature Tc, and the thermal stability parameter were determined by the DSC method. The ellipsometric data have provided Sellmeier-type dispersion relations of the refractive index of the investigated glasses. The optical parameters are used to calculate the molar refractivity, molar polarizability, oxide ion polarizability, molar cation polarizability, and a number of polarizable atoms per unit volume for every glass composition in order to interpret the refractive index of these glasses.

7

Metoda wyznaczania współczynników załamania na powierzchniach granicznych warstw dielektrycznych z obwiedni charakterystyk odbiciowych

Krasiński P., Tyszkiewicz C., Skolik M., Błaszczyk T.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 8

51--54

PL

W pracy przedstawiana jest nowa metoda wyznaczania wspólczynników załamania na powierzchniach granicznych warstw dielektrycznych z obwiedni ich widm odbciowych. Podawane są proste wzory na współczynniki załamania na powierzchniach granicznych warstwy, które weryfikowane są teoretycznie i eksperymentalnie. Wyliczone prezentowaną metodą współczynniki załamania używane były w obliczeniach widm odbiciowych, które porównywane są z wyjściowymi widmami eksperymentalnymi.

EN

The presentation shows the new method allowing determination of refractive indices at interfaces of dielectric films. The method is basing on the analysis of envelopes of reflectance spectra. In the presentation there are shown theoretical foundations of simple mathematical formulas, describing refractive index values at film interfaces as well as experimental results that postively verified our method. In the first step, values of the refractive index at films interfaces were determined using our method. In the second step, reflectance spectra were calculated using the values of refractive indices obtained in the first step and compared with measured ones

8

Thin SixNyCz films deposited from hexamethyldisilazane by RF PECVD technique for optical filter applications

Oleśko K., Szymanowski H., Gazicki-Lipman M., Balcerzak J., Szymański W., Pawlak W., Sobczyk-Guzenda A.

Materials Science Poland

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2018

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Vol. 36, No. 1

56--68

EN

This work initiates a series of reports aimed at a construction of rugate optical filters based on silicon rich materials of alternating gradients of refractive index n with the help of plasma enhanced chemical vapor deposition (PECVD) technique, The idea is to start deposition of high refractive index SixNy type of material using hexamethyldisilazane (HMDSN) vapor and nitrogen rich atmosphere, and then to gradually replace nitrogen with oxygen in that atmosphere in order to lower n down to a minimum characteristic of SixOy type of material. A return to initial gas composition should increase the index back to its maximum. In the present work, thin SixNyCz films were synthesized from a mixture of HMDSN vapor with gaseous NH3 and N2. The effect of NH3/N2 ratio on the coating morphology, its elemental composition, chemical bonding and optical properties was studied using scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultra-violet absorption spectroscopy and variable angle spectroscopic ellipsometry. The results show that films of the highest index of refraction and the lowest extinction coefficient have been deposited from the gas mixture containing 90 % of ammonia. These coatings are also characterized by the lowest carbon and the highest nitrogen contents.

9

Determination of different optical properties for cubic titanium dioxide: an AB-INITIO approach

Dash Debashish, Pandey Chandan K., Chaudhury Saurabh, Tripathy Susanta K.

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 3

223--232

EN

This paper presents an analysis of optical properties of cubic titanium dioxide (TiO2) using Orthogonalized Linear Combinations of Atomic Orbitals (OLCAO) basis set under the framework of Density Functional Theory (DFT). Many optical properties such as refractive index, extinction coefficient, reflectivity, absorption coefficient, photoconductivity, and loss coefficient have been studied and analyzed thoroughly. From the analysis of optical properties, it is seen that, cubic TiO2 supports interband transition between states. Reflectivity of pyrite structure TiO2 lies within IRvisible – UV region due to which it qualifies for coating industry. Furthermore, the results are compared with previous theoretical as well as with experimental results. It is found that DFT based simulation produces results which are close approximation to experimental results.

10

Właściwości kryształów fotonicznych umożliwiające ich wykorzystanie w poligrafii

Zwierzchaczewska M., Podsiadło H.

Acta Poligraphica

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2018

|

Vol. 12

71--81

EN

Photonic crystals are an innovative material and have recently been used in printing. They consist of dielectric layers of a variable refractive index. The change of this value may occur in one, two or three directions. Thanks to it, photonic crystals give the possibility of conscious control of the electromagnetic wave in the structure, which leads to the creation of photonic band gap, and this allows the conscious creation of color. It turns out therefore that the color is created not only as a result of the mixture of additive or subtractive basic colors, but also due to photonic changes as in the case of photonic crystals. Photonic crystals are used in printing as a method of securing documents. The deliberately designed width of the photonic band gap creates any color that can change under the influence of certain factors, such as the application of a magnetic field or a change in the angle of observation. Pigments containing photonic crystals make the item difficult to forge. So far, research has been conducted on the use of cognition of new properties of these crystals and on the use of those already known. Conducting experiments is expensive, however, the premonition of scientists allow to conclude that photonic crystals are a valuable material on which to focus more attention.

11

Indeks

Pniewski J.

Optyka

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2017

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Nr 5

76--80

12

Wpływ tlenku baru na właściwości szkieł tellurowych

Grelowska I., Pałczyńska N.

Szkło i Ceramika

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2016

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R. 67, nr 2

12--15

PL

W pracy przedstawiono badania dotyczące wpływu tlenku baru na właściwości szkieł tellurowych z układów TeO2–BaO–Na2O (TBN) oraz TeO2–BaO–WO3 (TBW). Wykazano, że szkła tellurowe z układu TBW charakteryzują się wyższą gęstością w stosunku do szkieł z układu TBN. Wyznaczono właściwości optyczne szkieł takie jak: współczynnik załamania światła, transmisja w zakresie widzialnym i w podczerwieni oraz współczynnik absorpcji. Na podstawie przeprowadzonych badań elipsometrycznych stwierdzono, że szkła TBW charakteryzują się wyższym współczynnikiem załamania światła w stosunku do szkieł TBN. Wyniki badań transmisji oraz współczynnika absorpcji wykazały wysoką przepuszczalność badanych szkieł tellurowych. Uzyskane parametry optyczne są interesujące z punktu widzenia konstrukcji układów optoelektronicznych.

EN

The aim of this work was the research on the effect of barium oxide content on tellurite glass properties of the TeO2–BaO–Na2O (TBN) and TeO2–BaO–WO3 (TBW) system. The TBW glasses are characterized by the higher density compared to the glasses of the TBN system. The optical measurements such as refractive index, transmission, and absorption coefficient have been done. On the basis of ellipsometric studies it was stated that TBW glasses are characterized by the higher value of the refractive index in comparison to TBN glasses. The transmission and absorption coefficient of glasses obtained are very high. All optical properties obtained are interesting due to their application in optoelectronic field.

13

Właściwości optyczne refrakcyjne wybranych olejków roślinnych

Andriyevsky B., Andriyevska L., Piecuch T., Kowalczyk A.

Rocznik Ochrona Środowiska

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2016

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Tom 18, cz. 1

597--608

PL

Współczynnik załamania n optycznie przezroczystego materiału jest ważną jego charakterystyką, która zależy od elektronowej struktury cząsteczek odpowiedniej substancji. W przypadku olejków roślinnych, zawierających stosunkowo słabo oddziałujące cząsteczki, są jednak własności, które zależą w znacznym stopniu od oddziaływania międzycząsteczkowego. Do takich własności można odnieść krzepnięcie i parowanie olejków. Ostatnie zjawisko wpływa prawdopodobnie w dużym stopniu na natężenie zapachu każdego olejku, który jest ważny w odpowiednich zastosowaniach praktycznych. W związku z tym wyniki badań zależności temperaturowych gęstości r(T) i współczynnika załamania n(T) olejków roślinnych mogą być pomocne w oszacowaniu stopnia oddziaływania międzycząsteczkowego i odpowiednich możliwości ewentualnych zastosowań praktycznych. W niniejszej pracy przedstawiono wyniki badań zależności temperaturowych w zakresie 20-60°C współczynnika załamania nD(T) i gęstości r(T) trzech olejków roślinnych: z pomarańczy, cytryny i grejpfruta. Do pomiarów bezwzględnego współczynnika załamania nD olejków na długości fali świetlnej lD = 589 nm wykorzystano standardowy refraktometr Abbe. Gęstość olejków ρ w temperaturze pokojowej była otrzymana poprzez mierzenie masy m określonej objętości V olejku i następujące obliczenie według wzoru definiującego ρ = m/V. Pomiary zależności temperaturowych współczynnika załamania n(T) i objętości olejków V(T) o określonej masie m wykonano przy pomocy 6-litrowego wodnego termostatu przepływowego typu “PolyScience model 912”. Otrzymane zależności wykorzystano do obliczenia charakterystycznych wielkości refrakcji właściwej i oddziaływania międzycząsteczkowego w olejkach według modelu pola efektywnego zaproponowanego we wcześniejszych pracach autorów (Andriyevsky, B., et al. 2009, Andriyevsky, B., et al. 2010). Na bazie przeprowadzonych badań densymetrycznych i refraktometrycznych olejków roślinnych z pomarańczy, cytryny i grejpfruta w zakresie temperatur 20-60°C sformułowano następujące wnioski.- Zależności temperaturowe gęstości ρ(T) i podatności elektrycznej cD(T) trzech olejków aproksymują się zadowalająco wielomianem pierwszego rzędu, ρ(T)=a+bT, z ujemnymi wartościami współczynników b.-Właściwości optyczne refrakcyjne olejków cytrynowego i grejpfrutowego są zbliżone w porównaniu do właściwości olejku pomarańczy.- Wiązania międzycząsteczkowe w olejkach z cytryny i grejpfruta mogą być słabsze niż w olejku z pomarańczy.

EN

Refractive index n of an optically transparent material is an important its parameter, which depends on the electronic structure of the corresponding substance. In the case of plant oils, consisting of the relatively weak interacting particles, there are properties that however depend greatly on the intermolecular interaction. These properties are the oils coagulation and vaporization. The last phenomenon influences probably greatly the odor intensity of each oil, which can be significant for certain applications. Therefore, results of the temperature dependences of density p(T) and refractive index n(T) of plant oils can be helpful for estimation of the degree of intermolecular interaction and corresponding possibilities of practical applications of oils. In the present paper, the results of study of the temperature dependences of refractive index nD(T) and density p(T) in the range of 20-60 degrees C have been presented for three plant oils obtained from orange, lemon and grapefruit. For measurements of the absolute refractive index nD of oils at the wavelength lambda(D) = 589 nm a standard Abbe refractometer was used. The oil's density p at ambient temperature was obtained by the measurement of the corresponding mass m and volume V, p = m/V. Measurements of the temperature dependences of refractive index n(T) and volume V(T) of the known mass of oil m were performed using the 6-liters water thermostat "PolyScience model 912". The dependences obtained have been used for calculation of the characteristic values of specific refraction and intermolecular interaction of the oils according to the model of the effective electric field proposed in the former publications of the authors (Andriyevsky, B., et al. 2009, Andriyevsky, B., et al. 2010). The following conclusions have been formulated on the basis of investigations of the orange, lemon and grapefruit plant oils done in the temperature range of 20-60 degrees C. 1. The temperature dependences of density p(T) and electric susceptibility X-D(T) are fitted satisfactorily by the first order polynomial, p(T) = a + bT, with negative coefficients b. 2. Refractive properties of the lemon and grapefruit oils are close in comparison to the analogous values for the orange oil. 3. Intermolecular bonds in the lemon and grapefruit oils can be weaker in comparison to the orange oil.

14

Wpływ temperatury na wartość współczynnika załamania w rdzeniu światłowodu jednomodowego

Torbus S. A.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 3

158--163

PL

W artykule omówiono budowę włókna światłowodowego, zdefiniowano profil współczynnika załamania w rdzeniu światłowodu oraz określono wpływ temperatury na wartość współczynnika załamania szkła optycznego. Korzystając z opracowanego w środowisku MathCAD modelu matematycznego światłowodu telekomunikacyjnego, określono wpływ temperatury na wartość współczynnika w jego rdzeniu, w zależności od długości fali świetlnej, stężenia molowego domieszki GeO2 oraz różnicy termicznej zmiany polaryzowalności i termicznej rozszerzalności objętościowej. Sformułowano wnioski dotyczące wpływu rozpatrywanych czynników na czułość temperaturową szkła optycznego o strukturze SiO2–GeO2 oraz przydatności tychże szkieł do realizacji polarymetrycznych czujników natężenia prądu wykorzystujących magnetooptyczne zjawisko Faradaya oraz rozłożonych czujników temperatury wykorzystujących wymuszone rozproszenie Rayleigha.

EN

The article discussed the construction of optical fiber, the definition of refractive index profile in the fiber’s coreand the influence of temperature on the refractive index of optical glass. Using the mathematical model of the single mode fiber, which was realized in an MathCAD application, the effect of temperature on the value of refractive index in their core, depending on the wavelength of the light, the molar concentration of GeO2 dopant and the difference between the thermal changes of polarizability and the thermal volumetric expansion were has been determined. Conclusions regarding the impact of the factors considered on the temperature sensitivity of optical glass structure SiO2–GeO2 and of the use of these glasses for the implementation of polarimetric current sensors used Faraday effect and distributed temperature sensors using simulated Rayleigh scattering have been formulated.

15

Determination of CdSxSe1-x thick films optical properties from reflection spectra

Tivanov M., Kaputskaya I., Patryn A., Saad A., Survilo L., Ostretsov E.

Przegląd Elektrotechniczny

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2016

|

R. 92, nr 9

88--90

EN

A method for determining the band gap value and the refractive index near the absorption edge from reflection spectra was tested for CdSxSe1-x films prepared using the screen-printing and sintering technique.

PL

Przeanalizowano metodę wyznaczenia szerokości przerwy energetycznej i współczynnika załamania z pomiarów widma współczynnika odbicie warstw CdSxSe1-x otrzymanych metodami sitodruku i konsolidacji termicznej (sintering technique).

16

Five-wavelength laser microrefractometer

Bodurov I, Yovcheva T, Sainov S

Optica Applicata

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2015

|

Vol. 45, nr 2

199--204

EN

Corresponding author: In this paper, the design and testing of a five-wavelength laser microrefractometer are presented. Five semiconductor lasers are used for the spectral region of 405–1320 nm. The presented device is based on the critical angle method. In this case, the critical angle of total internal reflection is determined with the help of a CCD camera detecting the disappearance of the diffraction pattern, created by a metal diffraction grating. The samples of a thin liquid layer (< 10 μm) are placed between a flint-glass prism and a chromium diffraction grating. The refractive indices of two matching liquid products of Cargille Laboratories are investigated for the approbation of the presented device. The measured values of the refractive indices are used for the dispersion curves construction. The obtained values of the refractive indices are compared with the catalog data given by the manufacturer.

17

Absorption coefficient along a propagated ultra-short laser pulse in the air based on Kramers–Kronig relations

Malekshahi M, Naghavi K

Optica Applicata

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2015

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Vol. 45, nr 4

501--512

EN

In this manuscript, some effects such as nonlinear Kerr, stimulated Raman, and plasma generation effects lead to obtaining the nonlinear refraction index of the air along an intense ultra-short laser pulse based on one-dimensional propagation analysis. The variations in the pulse frequency by the self-phase modulation effect are investigated for achieving the functionality of the refractive index to the frequency. The mentioned functionality allows implementing Kramers–Kronig relations to measure the absorption coefficient. Results indicate that the front of the laser pulse faces a high rate of the energy loss whereas the back of the pulse experiences a gain. The implementation of Kramers–Kronig relations for a theoretical calculation of absorption coefficient variation along a laser pulse propagating in the air in which we have simultaneously taken into account the three above-mentioned effects distinguishes our work from other studies.

18

Aqueous Solution and Computed Gas Phase Properties of Meclofenamic Acid Sodium Salt

Kharat S.J.

International Letters of Chemistry, Physics and Astronomy

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2015

|

Vol. 41

124--131

EN

Paper reports densities, ultrasonic velocities, and refractive indices of aqueous solutions of meclofenamic acid sodium salt (Na-MCF). Densities, ultrasonic velocities, and refractive indices have been measured at (298.15, 303.15, 308.15, and 313.15) K and at atmospheric pressure. Limiting molar volume and limiting molar isentropic compressibility have been calculated. DFT method has been used for computation of dipole moment, free energy, hydration free energy, and HOMO and LUMO energies of Na-MCF. Gas phase properties have been computed by the use of G09 W Software.

19

Study of optical parameters of two fluorinated isothiocyanato nematic liquid crystals exhibiting high birefringence

Devi T. K., Choudhury B., Bhattacharjee A., Dabrowski R.

Opto-Electronics Review

|

2014

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Vol. 22, No. 1

24-30

EN

Optical studies have been carried out on two fluorinated isothiocyanato nematic liquid crystal (LC) compounds 4'-butylcyclohexyl-3, 5-difluoro-4-isothiocyanatobiphenyl and 4'-pentylcyclohexyl-3, 5-difluoro-4- isothiocynatobiphenyl. Transition temperatures of the two samples were confirmed using a polarizing microscope. The two LC compounds were found to exhibit fairly high clearing temperatures. Measurements of refractive indices of the two compounds were done by using thin prism method with He-Ne laser beam of wavelength 630 nm. Birefringence of the two LC compounds was calculated from the measured refractive indices. Both the compounds are found to display fairly high values of birefringence. Validation of a modified four-parameter model, based on Vuks equation describing the temperature dependence of refractive indices of the two liquid crystals, is also presented in this paper. The model is validated by fitting the experimentally measured values of refractive indices, birefringence and average refractive indices of the two nematic LCs with the theoretical values. In this paper, the calculation of order parameters of the LCs is presented by using two methods: direct extrapolation method based solely on the birefringence data and by using modified Vuks method based on Haller’s extrapolation. As observed from the obtained results, this procedure of calculating order parameter gives very reasonable results.

20

Optyczne i strukturalne badania szkieł tellurowych z układu TeO2–WO3–PbO modyfikowanych tlenkami lutetu i lantanu

Burtan B., Grelowska I., Wasylak J., Reben M.

Materiały Ceramiczne

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2014

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T. 66, nr 1

27--31

PL

W artykule przedstawiono badania dotyczące wpływu tlenków lutetu i lantanu na właściwości fizykochemiczne szkieł tellurowych z układu TeO2–WO3–PbO. Przebieg przemian fazowych, zachodzących podczas ogrzewania szkieł, badano przy pomocy metody DTA, XRD oraz SEM. Przy pomocy spektroskopii MIR oraz Ramana określono wpływ modyfikatorów w postaci lantanu i lutetu na strukturę szkieł tellurowych. Na podstawie badań optycznych transmisji i odbicia potwierdzono wysoką przepuszczalność szkieł zwłaszcza w środkowej podczerwieni. Przy pomocy badań elipsometrycznych stwierdzono, że modyfikatory w postaci jonów Lu3+ i La3+ obniżają wartość współczynnika załamania światła.

EN

The goal of this work was to investigate the influence of lanthanum and lutetium oxides on physicochemical properties of the TeO2-WO3-PbO glass matrix. Differential thermal analysis DTA, XRD, SEM measurements have been considered in terms of the La2O3 and Lu2O3 addition. Raman and MIR spectroscopy was used for characterization of glasses. The Raman spectra of the glasses were interpreted in terms of the structural transformations produced by the modifiers. The reflectance, transmittance and ellipsometric measurements have been done. Decreasing of the refractive index of the base glass with the Lu3+ and La3+ ion doping has been found.