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1

Imaging polarimeter with high-accuracy measuring principles in crystal optics

Shopa Mykola, Kobyakov Serhiy, Shopa Yaroslav

Opto-Electronics Review

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2022

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Vol. 30, No. 3

art. no. e141948

EN

An imaging polarimeter based on the principles of high-accuracy polarimetry well known in crystal optics is proposed. The application of scientific digital cameras for performance light measurements leads to precise data on polarizers quality, i.e., maps of extinction ratio and transmission axis. Processing of numerous images, acquired at various settings in the polarizer-sample-analyser system, allows to determine the two-dimensional distribution of the phase retardation of birefringent plates. Several results of imaging polarimetry experiments on birefringent plates demonstrate the impact of multiple light reflections on the measured phase retardation values. Experimental data for LiNbO₃ and SiO₂ crystal plates have been presented, demonstrating the capabilities of the proposed type of imaging polarimeter in the crystal optics studies. This technique also allows the measurement of the eigen wave ellipticities, associated with the optical activity of crystals.

2

Polarization properties of nematic liquid crystal cell with tapered optical fiber

Marć Paweł, Stasiewicz K., Korec J., Jaroszewicz L. R., Kula P.

Opto-Electronics Review

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2019

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Vol. 27, No. 4

321--328

EN

In the paper, an extended analysis of the polarization properties of a liquid crystal cell with a biconically tapered single-mode telecommunication optical fiber was presented. These properties are a result of a sample geometry and used LC materials. They were analyzed by using two theoretical models based on the matrix decomposition methods, i.e., polar and singular-value one. By measuring Mueller matrices, information about losses, depolarization, dichroism and birefringence was obtained. In the experiment two types of tested samples filled with well-known 6CHBT and E7 liquid crystals were prepared and all optical parameters were shown as the voltage dependence. The tested samples have dichroic properties and for both models calculated PDL is similar and it increases from 2.6 to 6.6 dB for E7 and from 0.4 to 2.7 dB for 6CHBT with voltage changes within the range of 40 – 190 V. Optical losses simultaneously decrease from 30 dB to 27 dB and from 36 dB to 28 dB, respectively. The birefringence properties cannot be directly comparable due to differences between both applied models but voltage fluctuations of these parameters are not significant. These results confirm expected dichroic properties of designed device and complete knowledge about its working principles. Moreover, presented analysis validates usefulness of the singular-value decomposition model applied to dichroic optical fiber elements.

3

Ultrahigh nonlinear polarization maintaining dispersion compensating photonic crystal fiber

Ghunawat Ashish Kumar, Cherif Rim, Singh Ghanshyam

Optica Applicata

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2019

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Vol. 49, nr 1

51--63

EN

This work describes the suitability of a nano-dimension slot with low index material in the core region to achieve a highly nonlinear, polarization maintaining and dispersion compensating photonic crystal fiber. Our design is composed of a spiral shaped photonic crystal fiber with an elliptical slot made of silicon nanocrystals in the core region. The simulated results show that high nonlinear coefficients at the 1.55 μm wavelength for quasi-TE mode and quasi-TM mode are found to be equal to 1348 and 638 W–1m–1, respectively. The proposed design offers high birefringence up to 0.2503 and large negative dispersion value –1228 ps/nm/km. The proposed fiber has immense potential for realization of all-optical signal processing devices/networks and sensing applications while maintaining its polarization.

4

Tuning transfer function of fiber-optic Fabry–Pérot interferometer via introduction of birefringence in the cavity

Hirsch Marzena, Wierzba Paweł, Jędrzejewska-Szczerska Małgorzata

Optica Applicata

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2019

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Vol. 49, nr 2

241--248

EN

The study investigates the impact of birefringence exhibited by the cavity material of a fiber-optic Fabry–Pérot interferometer on its transfer function. The theoretical approach to analyze the effect of birefringence in the cavity of a plane Fabry–Pérot interferometer is described. The case of high- and low-finesse interferometer is investigated. It is shown that introduction of a birefringent medium of optimized parameters can be used to increase the density of interference fringes in certain wavelength range – the feature can be used either for reduction of the cavity length in an interferometric sensor or operation with sources of narrower spectral characteristics.

5

Numerical analysis of dual-core photonic crystal fiber based temperature and pressure sensor for oceanic applications

Jegadeesan Subramani, Dhamodaran Muneeswaran, Sri Shanmugapriya Swaminathan

Optica Applicata

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2019

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Vol. 49, nr 2

249--264

EN

In this paper, a microstructured optical fiber with dual core was proposed which is known as photonic crystal fiber. Specific optical properties of a dual-core photonic crystal fiber were used to obtain high birefringence, small beat length, flattened dispersion, for different values of structural parameters varied over a wide range of wavelength and analyzed for application such as temperature and pressure sensors. The sensitivity of the temperature sensor is calculated as 20 pm/°C for 6 cm fiber, the sensitivity of the pressure sensor for a range from 0 to 1000 kPa is calculated as –10.5 nm/MPa.

6

Locally-induced permanent birefringence by polymer-stabilization of liquid crystal in cells and photonic crystal fibers

Chychłowski M. S., Ertman S., Rutkowska K., Strzeżysz O., Dąbrowski R., Woliński T. R.

Opto-Electronics Review

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2018

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Vol. 26, No. 3

242--246

EN

The aim of this work was to induce permanent birefringence both in typical liquid crystal cells and photonic crystal fibers (PCFs) by photo-polymerization. For this purpose three different liquid crystalline materials, namely E7, 5CB, and 6CHBT were combined with a mixture of RM257 monomer and a UV sensitive initiator with the percentage weight less than 10%. Due to the photo-polymerization process it was possible to achieve polymer-stabilized liquid crystal orientation inside LC cells and micro-sizedcylindrical glass tubes. In particular, periodic change in spatial molecular orientation was achieved by selective photo-polymerization. Successful results obtained in these simple geometries allowed for the experimental procedure to be repeated in PCFs leading to locally-induced permanent birefringence in PCFs.

7

Dispersion of fluorescent dye in the nematic liquid crystal : enhanced photoluminescence and high birefringence

Pathak G., Agrahari K., Roy A., Srivastava A., Strzezysz O., Garbat K., Manohar R.

Opto-Electronics Review

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2018

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Vol. 26, No. 4

317--324

EN

In the present investigation optical, electro-optical and dielectric properties have been measured for nematic liquid crystal (NLC) material 1550C which is consisted of 4’-(trans, trans-4-alkylbicyclohexyl) carbonates and 4’-(4-(trans,trans-4-alkyl)-4-cyanobicyclohexane, dispersed with fluorescent dye (Benzo 2,1,3 Thiadiazole) in two different concentrations. Photoluminescence has been enhanced for dye dispersed system which is the key finding of this investigation. UV absorbance study has also been performed and found to be increased for composite system. Enhanced birefringence after dispersion of dye into pure NLC is also a prominent result of this investigation. Relative permittivity, threshold voltage and dielectric anisotropy have also been measured and found to be increased. The outcome of the present work may be very useful in the construction of liquid crystal displays (LCDs).

8

Analysis of birefringence property of three different nematic liquid crystals dispersed with TiO₂ nanoparticles

Pathak G., Katiyar R., Agrahari K., Srivastava A., Dabrowski R., Garbat K., Manohar R.

Opto-Electronics Review

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2018

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Vol. 26, No. 1

11--18

EN

In the present work TiO₂ nanoparticles (NPs) have been dispersed into three different nematic liquid crystals (2020, 1823A and 1550C) in different concentration. The value of the birefringence (Δn) has been calculated by the transmitted intensity method at a 632.8 nm wavelength. NLC 2020 used in the present study is a high birefringent material (Δn = 0.44), NLC 1550C is a low birefringent material (Δn = 0.067) and NLC 1823A is a mid birefringent material (Δn = 0.14). An increased value of birefringence has been found after dispersion of TiO₂ NPs in all three NLCs but this increment depends upon the concentration of the dopant material, temperature range and chemical character of the mixtures. It is suggested that this LC materials can be applicable in making of phase shifters, compensators and many more photonic devices.

9

2D-Mueller-matrix tomography of optically anisotropic polycrystalline networks of biological tissues histological sections

Trifonyuk L., Baranowski W., Ushenko V., Olarc O., Dubolazov A., Ushenko Yu., Bodnar B., Vanchulyak O., Kushnerik L., Sakhnovskiy M.

Opto-Electronics Review

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2018

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Vol. 26, No. 3

252--259

EN

A new technique of Mueller-matrix mapping of the birefringent structure of biological preparations of human organs tissues is suggested. The algorithms of reconstruction of average values and magnitude of fluctuations of the phase (birefringence) and amplitude (dichroism) of optically anisotropic structure of myocardium and connective tissue component of the vaginal wall histological section are proposed.The magnitudes and ranges of changes in the statistical moments of the 1st-4th order that characterize the distribution of average values and magnitude of fluctuations of birefringence and dichroism of the myocardium and connective tissue of the vaginal tissues histological sections were determined. Joint studies of distributions of the characteristics of phase and amplitude of the anisotropy of myocardium and connective tissue component of the vaginal wall tissues of different states were performed. The cases of various necrotic changes in the myocardium and pathological conditions of the vagina wall (prolapse of the genitals) are examined. Balanced accuracy of the method of Mueller-matrix polarization-phase and diffuse tomography of optically anisotropic polycrystalline networks in the differentiation of necrotic and pathological changes in human organs is determined.

10

Sensitivity and dynamic phase response to thermal radiation of a polarization-maintaining fiber

Kyselak M., Dvorak F., Maschke J., Vlcek C.

Optica Applicata

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2018

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Vol. 48, nr 2

249--261

EN

This paper deals with the phase shift development between two polarization modes in birefringent fiber, caused by body heat transfer of different temperatures. The aim is to analyze sensitivity and dynamic behaviors, which are significant when optical fiber is used as a sensor of temperature field disturbance. The analysis is based on the values measured during thermal exposure of a section of type PANDA birefringent optical fiber to heat emitted by an exposure body of chosen temperature, placed at a defined distance. The effect of heat transfer through conduction and convection is suppressed by shielding with plastic wraps. The analyzed results, the Stokes parameters and subsequent phase shift, are measured by the polarimeter. The paper follows up on previously published measurement results.

11

Design and Analysis of Single Mode Photonic Crystal Fibers with Zero Dispersion and Ultra Low Loss

Kumar P., Tripathy A., Roy J. S.

International Journal of Electronics and Telecommunications

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2018

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Vol. 64, No. 4

541--546

EN

PCFs (Photonic Crystal Fibers) with ‘T’ – shaped core have been proposed in this paper. ‘T’ –shaped core PCF structures have been analyzed using two different background materials: silica and lead silicate. A total of 360° rotation at an interval of 90° has been introduced in the design of PCF structures. PCF structures A, B, C and D with rotation of 0°, 90°, 180° and 270° have silica as wafer. Similarly PCF structures E, F, G and H with similar rotation have lead silicate as background material. Numerical investigations shows structures ‘D’, ‘F’, ‘G’ and ‘H’ to have anomalous dispersion. PCF structures ‘F’, ‘G’, and ‘H’ have reported birefringence of the order of 10⁻². Besides, other PCF structures report birefringence of the order of 10⁻³. Ultra low confinement loss has been observed in all the investigated PCF structures. Moreover, splice loss observed by the structure is very low. Large mode area has been shown by all the designed PCF structures.

12

Dual-wavelength laser polarimeter and its performance capabilities

Shopa Y., Shopa M., Ftomyn N.

Opto-Electronics Review

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2017

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Vol. 25, No. 1

6--9

EN

A dual-wavelength optical polarimetric approach has been proposed as a means of elimination of the systematic errors and estimation of the optical anisotropy parameters for a single DKDP crystal. Our HAUP-related polarimeter uses two semiconductor lasers with the neighbouring wavelengths of 635 nm and 650 nm. Based on the temperature dependence analysis of small characteristic azimuths of light polarization with respect to the axis of the sample, we found the parameters of imperfections of polarization system. We acquired eigen waves ellipticities in a DKDP crystal and found perpendicular to the optic axis value of the optical rotatory power. Our results correlate positively with previously measured data for KDP crystals.

13

Phase response of polarization-maintaining optical fiber to temperature changes

Kyselak M., Dvorak F., Maschke J., Vlcek C.

Optica Applicata

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2017

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Vol. 47, nr 4

635--649

EN

This paper deals with the phase shift development in the polarization-maintaining fiber owing to different temperatures of an applied defined body, where both polarization axes are excited. A variation of the Stokes parameters induced by the phase shift is expressed by the Jones matrix and a depiction on the observable Poincaré sphere. The temperature response of polarization-maintaining fiber and the effects of heat transfer on the phase shift variation of polarization-maintaining fiber were described theoretically. The time dependence of the phase shift development and its direction of rotation on the observable Poincaré sphere was measured and presented graphically. In addition, different response measures for higher and lower temperatures compared with the ambient temperature were experimentally evaluated.

14

Investigation on optical, electrical and etching properties of 2-aminopyridinium 4-aminobenzoate: A phase matchable organic single crystal for optoelectronic device applications

Chandra L., Chandrasekaran J., Perumal K., Babu B., Jayaramakrishnan V.

Materials Science Poland

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2017

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Vol. 35, No. 1

126--134

EN

NLO active 2-aminopyridinium 4-aminobenzoate (APAB) single crystals were successfully grown by the standard slow evaporation technique. The crystallinity of the grown crystals was analyzed through X-ray diffraction (XRD) measurements. Fourier transform infrared (FT-IR) spectroscopic studies were also performed for the identification of different modes present in the compound. The UV-Vis absorption and transmittance spectra were recorded for the grown crystal and the optical band gap was calculated. Birefringence and etching studies were also carried out. The dielectric study showed that the dielectric constant decreased with an increase in frequency. The photoconductivity study revealed its positive photoconducting nature. Theoretical HOMO LUMO investigations were also made for the crystal. The relative SHG efficiency of the material was investigated by the Kurtz and Perry powder technique. The phase matching property of the crystal was studied through the SHG dependence of average particle sizes.

15

Soft glass spiral photonic crystal fiber for large nonlinearity and high birefringence

Revathi S, Inabathini S, Sandeep R

Optica Applicata

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2015

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Vol. 45, nr 1

15--24

EN

This paper presents a soft glass spiral photonic crystal fiber with circular air holes for achieving high birefringence, large nonlinearity and large negative dispersion. The material used here for designing the fiber is soft glass (SF-57). A central defect air hole is being introduced in the core for achieving high birefringence and for different ellipticity ratios the effect of various optical properties of a photonic crystal fiber are studied. The structure proposed has a high birefringence in the order of 10–2, high nonlinearity of 5828 W–1km–1 and high negative dispersion of –1546.6 ps/nm•km at 0.850 μm. A numerical approach based on the finite element method is used for the design and simulation of the structure. Due to the optimization in the cladding air holes, the fiber can be used as polarization maintaining fibers, in dispersion compensation and other nonlinear applications.

16

Measurement of pressure sensitivity of modal birefringence of birefringent optical fibers using a Sagnac interferometer

Kaczmarek C., Wójcik W.

Optica Applicata

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2015

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Vol. 45, nr 1

5—14

EN

The paper presents a method of measuring the sensitivity of modal birefringence to pressure in birefringent optical fibers, based on a Sagnac interferometer with a birefringent fiber. In this method, the pressure sensitivity of modal birefringence of the optical fiber is determined on the basis of the measurement of the pressure sensitivity of the Sagnac interferometer including the fiber being measured, and the measurement of the group modal birefringence of that fiber, which is also performed by using the Sagnac interferometer. Utilizing the above method, measurements were performed of the pressure sensitivity of modal birefringence of birefringent optical fibers: a photonic crystal fiber and a bow-tie fiber, in the wavelength range 1460–1600 nm. Presented are the results of these measurements and their comparison with the results obtained by using different methods for the same types of fibers.

17

UV-Induced Anisotropy in CdBr2-CdBr2: Cu Nanostructures

El-Naggar A. M., Albassam A. A., Oźga K., Szota M., Kityk I. V.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3A

2029--2032

EN

We have found an occurrence of anisotropy in the nanostructure CdBr2-CdBr2: Cu nanocrystalline films. The film thickness was varied from 4 nm up to 80 nm. The films were prepared by successive deposition of the novel layers onto the basic nanocrystals. The detection of anisotropy was performed by occurrence of anisotropy in the polarized light at 633 nm He-Ne laser wavelength. The occurrence of anisotropy was substantially dependent on the film thickness and the photoinduced power density. Possible mechanisms of the observed phenomena are discussed.

PL

Wykryto pojawienie się anizotropii w nanostrukturalnych warstwach nanokrystalicznych CdBr2-CdBr2: Cu. Grubość warstwy zmieniano w zakresie od 4 nm do 80 nm. Nanostrukturalne warstwy otrzymano poprzez kolejne osadzanie na nowych warstwach na podstawie nanokrystalitów. Detekcję anizotropii wykonano w spolaryzowanym świetle lasera gazowego He-Ne o długości fali 633 nm. Anizotropia optyczna występująca w warstwach w znacznym stopniu zależy od grubości warstwy i gęstości mocy indukowanej światłem. Omówiono możliwe mechanizmy obserwowanego zjawiska.

18

Zjawiska piezooptyczne i elastooptyczne w fotonicznych kompozytach polimerowych

Lesiak P.

Prace Naukowe Politechniki Warszawskiej. Fizyka

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2014

|

z. 57

3-105

PL

W pracy przedstawiono zwięzłą analizę zarówno numeryczną, jak i eksperymentalną, zjawisk piezooptycznych i elastooptycznych w fotonicznych kompozytach polimerowych. Do analizy wymienionych zjawisk użyto mikrostrukturalnych światłowodów polimerowych, co w bardzo przejrzysty sposób uwidoczniło odkształcenia, jakie pojawiają się w kompozycie polimerowym w momencie laminacji. Eksperyment ten ułatwił w znacznym stopniu analizę numeryczna wpływu jaki wywiera na dowolny światłowód skurcz polimeryzacyjny oraz umożliwił ocenę stopnia wpływu zjawiska elastooptycznego na mikrostrukturalny światłowód polimerowy, a przez to rozróżnienie go od zjawiska piezooptycznego. Przeprowadzona analiza otrzymanych wyników wykazała, że znaczenie ma takie orientacja głównych osi światłowodu względem włókien zbrojenia. W zależności od orientacji światłowodu w fo-tonicznym kompozycie polimerowym, zjawiska piezooptyczne lub elastooptyczne mogą wzmocnić lub osłabić wpływ skurczu polimeryzacyjnego. Dodatkowo istnieje możliwość zmiany charakterystyki włókna światłowodowego- wzmocnienie lub osłabienie czułości światłowodu na wybrany czynnik zewnętrzny. W pracy wykazano również, że wpływ temperatury na zmianę naprężeń we włóknie światłowodowym ma swoje główne źródło w zjawisku zwanym rozszerzalnością, cieplną i dotyczy głównie deformacji kompozytu polimerowego. Analizowane problemy związane z laminacją, włókien światłowodowych mogą zostać rozwiązane poprzez zastosowanie miękkiej warstwy lakieru pokrywającego światłowód. Zebrana wiedza została wykorzystana do zaprojektowania hybrydowego czujnika światłowodowego do równoczesnego pomiaru naprężeń i temperatury w kompozycie polimerowym.

EN

In this work, both numerical and experimental results of piezooptic and elastooptic phenomena in photonic polymer composites are presented. This new material consists of a polymer composite and a polymer highly birefringent (HB) microstructured fiber. The polymer fiber can easily reveal deformations occurring in the material during the lamination process. The experimental results obtained can facilitate and separate the numerical analysis of both piezooptic and elastooptic phenomena. Additionally, this work shows that thermal expansion of the composite material is the main reason for the observed changes in stress distribution within the optical fiber during the heating process. Furthermore. the piezooptic and elastooptic phenomena in the optical fibers strongly depend on the angular orientation of the fiber within the composite material. Depending on the orientation of the fiber, stress sensitivity can be either increased or decreased under external perturbation. Polymer HB microstructured fibers embedded in the composite material should be surrounded by an additional soft buffer coating. This additional coating of optical fibers can absorb all adverse stress that appears during the manufacturing process of phot nic polymer composites. The numerical calculations and experimental results presented in this work give the possibility to create a new hybrid sensor by combining two types or polarimetric sensors that are based on a side-hole fiber and an HB photonic crystal fiber (PCF). Both sensors are strain sensitive but only one of them (HB PCF) is temperature insensitive. This combination gives us the possibility to measure strain independently from ambient temperature. The proposed hybrid configuration can be effectively used for more reliable strain and temperature measurements and can be implemented in a wide range of sensing applications.

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

|

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

Experimental and Numerical Simulation Study of an Air drawing Model of Polyethylene Terephthalate (PET) Polymer and Model of Air Jet Flow Field in the Spunbonding Nonwoven Process

Bo Z

Fibres & Textiles in Eastern Europe

|

2014

|

Vol. 22, no. 1 (103)

89--96

EN

An air drawing model of polyethylene terephthalate (PET) polymer and one of the air jet flow field in the spunbonding process are established. The air jet flow field model is solved and simulated by means of the finite difference method. Numerical simulation computation results of the distributions of air velocity match quite well with the experimental data. The air drawing model of the polymer is solved with the help of distributions of air velocity measured by Particle Image Velocimetry. The model’s predictions of filament fiber diameters, crystallinities and birefringences coincide well with the experimental data. Therefore it can be concluded that a higher initial air temperature can yield finer filament fiber diameter, and a higher initial air velocity can produce a finer fiber diameter as well. The experimental results show that the agreement between the results and experimental data is much better, which verifies the reliability of these models. Also they reveal great prospects for this work in the field of the computer assisted design (CAD) of the spunbonding process.

PL

Opracowano model przepływu powietrza nadmuchiwanego przy wytwarzaniu włóknin spunbonded z PET. Model pola przepływowego powietrza wydmuchiwanego z dyszy został rozwiązany i zasymulowany za pomocą metody skończonych różnic. Wyniki numerycznej symulacji rozkładu prędkości powietrza zgadzają się z wynikami eksperymentalnymi mierzonymi za pomocą analizy obrazu cząstek. Przewidziane w wyniku analizy modelu średnice włókien, krystaliczność i dwójłomność zgadzają się z wynikami doświadczalnymi. Dlatego można wnioskować, że wyższa temperatura początkowa może prowadzić do cieńszych włókien, podobnie jak wyższa prędkość początkowa. Jak wynika z przeprowadzonej analizy, sposób rozwiązania tego zagadnienia może być pomocny przy projektowaniu procesu otrzymywania włóknin w systemie spunbonded.