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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. [ABSTRACT FROM AUTHOR]

Abstract The surface polarization scattering is investigated in terms of the coherence matrix for the electric field scattered from a birefringent material with a random interface between its surface and air. The relationship between the statistical properties of the scattered light at the scattering surface and the micro-structure of the anisotropic media has been explored for the first time to understand the underlying mechanism of the surface scattering phenomena for the electric field with random states of polarization. [ABSTRACT FROM AUTHOR]

A birefringent reconfigurable metasurface at visible wavelengths was obtained by combining an Au nanograting metasurface, which shows very high birefringence characteristics in visible light, and a microelectromechanical system actuator. The system was based on the electrostatic out-of-plane motion of the nanograting and it was developed by microfabrication. The modulation of retardation was achieved at a wavelength of 633 nm by up to 25.3° (from 21.5° to 46.8°) by applying a voltage in the range of 0–200 V. [ABSTRACT FROM AUTHOR]

The paper presents a proposal on a new concept of opto-mechanic oscillatory system applying an optic birefringent crystal and a laser. Additionally to the crystal and the laser, the system uses an optic modulator maintaining mechanic torsion oscillations in the system. The principle of the system operation is described using traditional theory of optic waves in crystals and also applying the corpuscular approach based on the concept of energy and momentum of photons. We prove that operation of the system is most efficient in case of optic crystals demonstrating strong birefringence. [ABSTRACT FROM AUTHOR]

Light field near‐to‐eye display (LFNED) achieves lightweight device and solves accommodation‐convergence conflict. However, low spatial resolution of LFNED brings users bad immersive experience. In this paper, the new method proposed using birefringent plate to enhance image resolution. In results, our method apparently improves resolution in LFNED. [ABSTRACT FROM AUTHOR]

The near‐eye display for augmented display using a birefringent crystal has been proposed for providing the accommodation. Since the birefringent crystal has unique optical property that the refractive index is modulated according to the polarization state, it can be used for accommodative head‐mounted display for augmented reality by making multiple image planes. We describe the two near‐eye display systems using birefringent crystal and analyze the interpolation method between multiple image planes. [ABSTRACT FROM AUTHOR]

The synthetic protocols for symmetrical/unsymmetrical 3,6-disubstituted 1,1,2,2-tetrafluorocyclohexane molecules were successfully established for the first time. Some of thus obtained tetrafluorinated cyclohexanes underwent recrystallization to afford trans -configured products preferentially. One of the unsymmetrical trans -disubstituted tetrafluorocyclohexanes, trans -1-ethyl-2,2,3,3-tetrafluoro-4-[4-( trans -4- n -propylcyclohex-1-yl)phenyl]cyclohexane, was found to possess a low birefringence Δ n (0.073) and a large negative dielectric anisotropy Δ ε (–9.4) in a binary mixture system, which were very prominent as characteristics of LC molecules in VA-mode driving LC displays. [ABSTRACT FROM AUTHOR]

In this work, highly birefringent large mode area (LMA) photonic crystal fiber (PCF) structure for interferometric sensor applications is proposed. The effective mode area, birefringence and the sensitivity coefficient of the proposed PCF structure by employing the full vectorial finite element method (FV-FEM) have been thoroughly investigated. The numerical results have shown that proposed structure simultaneously offers high birefringence of order 10, adequately LMA and high sensitivity for various liquid analytes by employing the elliptical liquid core holes. [ABSTRACT FROM AUTHOR]

Optical activity is investigated in a chiral medium by employing the four level cascade atomic model, in which the optical responses of the atomic medium are studied with Kerr nonlinearity. Light entering into a chiral medium splits into circular birefringent beams. The angle of divergence between the circular birefringent beams and the polarization states of the two light beams is manipulated with Kerr nonlinearity. In the stationary chiral medium the angle of divergence between the circular birefringent beams is calculated to be 1.3 radian. Furthermore, circular birefringence is optically controlled in a spinning chiral medium, where the maximum rotary photon drag angle for left (right) circularly polarized beam is ±1.1 (±1.5) microradian. The change in the angle of divergence between circular birefringent beams by rotary photon drag is calculated to be 0.4 microradian. The numerical results may help to understand image designing, image coding, discovery of photonic crystals and optical sensing technology. [ABSTRACT FROM AUTHOR]

It is shown for glass with the composition (molar content) 40PO, 55ZnO, 4AgO, and 1GaO that a femtosecond laser beam can form simultaneously in glass luminescent nanoparticles of silver and micron-size birefringent regions, whose properties depend on the polarization and intensity of the laser beam. [ABSTRACT FROM AUTHOR]

A strong and broadband negative group delay (NGD) is demonstrated in a circular waveguide with an asymmetric cross-shaped slotted structure in the millimeter-wave region. For an input of 45° linear polarization (relative to the orientation of the cross-shaped slots), the NGD fractional bandwidth is as high as 3.57%, in which the optimal group advancement obtained is nearly 24 times greater than the delay traveling with the speed of light in vacuum. This further indicates a very high fractional advancement of 12.10%. In addition, the NGD can be controlled by adjusting the polarization azimuthal angle of the incident pulse. The observed tunable NGD effect is attributed to the destructive cross interference between the two polarization eigenstates, which effectively reduces the released field energy at the observed polarization channel. A general theory is provided with excellent agreement in the experimental and simulation results. [ABSTRACT FROM PUBLISHER]

ABSTRACT Poly(trimethylene terephthalate) (PTT), a highly birefringent aromatic polyester, has been utilized to understand the mechanisms of crystal assembly into diversified types of banded spherulites. PTT exhibits three main types of banded spherulites (i.e., concentric, single-spiral, and double-spiral) co-existing in sample films melt-crystallized at 165 °C, regardless of sample thickness. The three types differ in their banding structures, interference color distributions, and nuclei geometries (S-shape, Z-shape, or dot-shape). Core diameter, band spacing ratio, and height difference (Δ z) around the core are the three key parameters of different banding patterns in PTT spherulites. Formation mechanism for three types of banded spherulites has been interpreted, and found to be highly correlated with the initial geometry shapes of their nuclei. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1207-1216 [ABSTRACT FROM AUTHOR]

This article presents the simulation, fabrication, and experimental characterization of a surface plasmonic resonance (SPR) sensor integrated with an acoustic sensing compatible substrate. The SPR sensor is designed to work in the visible region with gold nanodisc arrays fabricated on LiNbO3, which is both piezoelectric and birefringent. A linear relationship between resonance wavelength and varying liquid refractive indices were observed in experiments, and a sensitivity of 165 nm/refractive index unit was obtained. Polarization effects of the birefringent property of the Y-cut LiNbO3 substrate have been investigated, which can also be applied to X-cut LiNbO3. Our study demonstrates the feasibility of an SPR sensor device utilizing a birefringent substrate, which has acoustic wave compatibility and can pave the way toward much more robust and flexible biosensing devices. [ABSTRACT FROM AUTHOR]

Both cylindrical scatterers and birefringent media may contribute to the anisotropy of tissue, where anisotropy can be characterized using polarization techniques. Our previous studies have shown that a layer of well-aligned cylindrical scatterers displays anisotropic properties similar to those of a piece of birefringent media, whose equivalent extraordinary axis is along the axial direction of the cylinders. We focused on a sample consisting of two layers of anisotropic media, with each layer having a different orientation; the characteristics of this sample were representative of the properties of multilayer fibrous tissues. Using a Mueller matrix decomposition method, we examined in detail how the total retardance and the equivalent extraordinary axis of the bilayered sample varied with changes in the retardance of the two layers and the direction of the extraordinary axis. The results of this study showed that, in such bilayer samples, a layer of well-aligned cylindrical scatterers generated a retardance that behaved exactly like the retardance generated by a piece of birefringent media. The simulated results were also confirmed by the results of experiments using aligned glass fibers. [ABSTRACT FROM AUTHOR]

We propose a unique optical system for measuring the retardation of birefringent films using a pair of liquid crystal (LC) gratings; that is, the examined birefringent films are inserted between two LC gratings. Because the LC grating functions as a polarization beam splitter for circularly polarized light, the proposed system is optically equivalent to the measurement system using a pair of two circular polarizers. First, the polarization splitting performance of the LC grating is discussed. It is found that a sufficiently high voltage (such that the retardation is less than a half wavelength) has to be applied for the almost pure circularly polarized diffracted light. Next, the measurement of the retardation of a homogeneous LC cell as an examined birefringent film was demonstrated using the proposed method. The proposed method is revealed to have the same measurement performance as that of the conventional method using a pair of linear polarizers and has an advantage that there is no need for the optic axis of the test birefringent specimen to be set at a specific angle. [ABSTRACT FROM AUTHOR]

Self-assembled nanostructures created by femtosecond laser irradiation are demonstrated in alkalifree aluminoborosilicate glass. The growth of the induced retardance associated with the nanograting formation is three orders of magnitude slower than in silica glass and is observed only within a narrow range of pulse energies. However, the strength of retardance asymptotically approaches the value typically measured in pure silica glass, which is attractive for practical applications. A similar intensity threshold for nanograting formation of about 1 TW/cm² is observed for all glasses studied. The radially polarized vortex beam micro-converter designed as a space-variant quarter-wave retarder for the near-infrared spectral range is imprinted in commercial Schott AF32 glass. [ABSTRACT FROM AUTHOR]

An analysis into the phase matching condition of four-wave-mixing in highly birefringent photonic crystal fiber is presented to yield twelve independent processes combining the nonlinear terms with those of linear terms. The pump wavelength, power and pump pulse incident angles effects on the anti-Stokes frequency shifts are analyzed. The results show that the incident polarization angles along the slow-axis of the PCF, anti-Stokes wavelength is shorter than the case of along the fast-axis. In the case of a divided pump polarization, the frequency shifts decrease gradually with the increase of the incident angles. The pump wavelength is much more important factor in the phase-matched processes, but not sensitive to change of power. Experimental results link power, incident angles and phase-matched wavelengths are presented. Experiments demonstrate that the variation of the pump pulse parameters results in the anti-Stokes lines generation at 550 and 620 nm, which is in good agreement with the theoretical analysis. Furthermore, there exists the polarization-, power-independent anti-Stokes emissions. [ABSTRACT FROM AUTHOR]

We report properties of zero birefringent xZnO-(67-x)SnO-(33-y)P2O5-yB2O3 glasses, within 18.5 ≤ x ≤ 22 and y = 0, 3, and 10 mol. %. These compositions of boro-phosphate glasses provide both zero photoelastic constant (PEC) and improved water durability. x = 19 and y = 3 compositions show minimum PEC of -0.002 x 10-12 Pa-1, which can contribute to candidate material for fiber current sensor devise without lead. The structures of zero photoelastic glasses were investigated by Raman scattering and nuclear magnetic resonance spectroscopies. Compositions of zero PEC glasses are explained by the empirical model proposed by Zwanziger et al. [Chem. Mater. 19, 286-290 (2007)]. [ABSTRACT FROM AUTHOR]

Sutures are used widely in the medical community for wound closure. Traditional sutures have a smooth surface and secure a wound by means of a knot tied at either end, which tensions the suture and holds the wound closed. However, biomechanical testing of traditional sutures has demonstrated that the knot is the most common site of failure due to a decrease in the tensile strength. In an effort to minimize knot failure of monofilament sutures, barbed sutures have been developed that obviate the need for knots during wound closure. In this study, the photoelastic coating method was employed to perform a comparative measurement of the stresses induced in the wound region for barbed versus monofilament sutures under wound flexure. Because of the difficulty in using actual sutured wounds, a wound analog model was employed made of a special foam material commonly used by surgeons for practicing wound closure skills. An examination of the changes that occurred in the incision line fringe numbers during flexure of the wound analog model was then used as an in vitro measurement of the effectiveness of barbed versus monofilament sutures in retaining simulated wound closure stress magnitude and distribution. [ABSTRACT FROM AUTHOR]

ABSTRACT Polymer dispersions containing crystalline nanocellulose have been used as birefringent inks. When printed onto dark paper, the letters are darker than the background if viewed without polarizers, while they are brighter than the background if viewed with crossed polarizers. This type of contrast inversion can have applications in security printing and optical authentication. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41063. [ABSTRACT FROM AUTHOR]

Novel birefringent liquid crystal polymer homeotropic films have been coated on semiconductor solar cells to improve the effective incident sunlight angles. The liquid crystal polymer precursor, based on reactive mesogens, is fluidic and flows like liquid. It would distribute uniformly on the solar cell sample surface by any traditional coating technique. The birefringence for light, due to the liquid crystal retardation properties, manipulated the optical length and the deflection of incident light, thus allowed an increase in the energy conversion efficiency. The expensive sunlight tracking systems could be avoided. The processing parameters can be tuned such as different mesogen concentrations and plate speeds of spin-coating. The results showed that the solar cell conversion efficiency was improved from 14.56% to 14.85% at an incident sunlight angle of 15°. It was further improved from 13.40% to 13.81% when the angle was 30°. The interesting angular dependency on solar cell efficiency enhancement has been evaluated. [ABSTRACT FROM AUTHOR]

We theoretically investigate a 25GHz multichannel filter based on ring cavity birefringent optical interleaver for dense wavelength division multiplexing (DWDM) transmission systems. The simulation tool used in this work is the Advanced System Analysis Program (ASAP) optical modeling software. We improve the dispersion performance by employing λ/6 and λ/4 wave plates as birefringent compensators for interleavers. The new structure exhibits a high performance with nearly zero ripple, a channel isolation greater than 102 dB, and a passband utilization of 86% within the C-band. The research results illustrate that our modified scheme can improve the dispersion of more than 76.6% in comparison with the previous studies of optical interleaver with birefringent crystal and ring cavity structures. [ABSTRACT FROM AUTHOR]

Abstract: We study the intensity point spread function (IPSF) of a uniaxial birefringent lens sandwiched between two linear polarizers under broadband illumination having flat-top spectral profile. The optic axis of the birefringent crystal is perpendicular to the lens axis. For monochromatic input illumination, a low-power birefringent lens offers enhanced resolution under parallel-polarizers configuration and apodization under crossed-polarizers configuration with a single focus as well. At a relatively high value of birefringence parameter, the proposed system behaves as a double-focus lens. The present communication uses a novel technique to study the effect of polychromatic illumination on the imaging characteristics of birefringent lenses. The studies reveal that the imaging characteristics of the low-power birefrigent lens does not deteriorate considerably under polychromatic illumination. However, for a polychromatic beam with large bandwidth, the imaging behavior of the system having high birefringence parameter deviates appreciably from that under strictly monochromatic illumination. The said system even loses its inherent bi-focal nature due to depolarization of polarized polychromatic light upon passage through the birefringent crystal. [Copyright &y& Elsevier]

The study investigates a case of a low‐coherence fiber‐optic Fabry–Pérot interferometer with a nanocrystalline diamond (NCD) mirror. The method of achieving double density of interference fringes is proposed by the application of birefringent material in the cavity of the interferometer. It can be used to reduce sample volume in comparison to conventional interferometers. The use of a biocompatible diamond mirror makes it specifically well suited for application in biosensing. The fabrication process and surface characterization of the nitrogen‐doped NCD and boron‐doped NCD films are described. The results of numerical modeling and experimental measurements are discussed. The application of boron‐doped diamond and nitrogen‐doped diamond films as a mirror in a fiber‐optic Fabry–Pérot interferometer is presented. This enables performing biomedical measurements. The birefringent material is introduced into sensor cavity which allows us to reduce the sample volume for measurements. This could be useful in case of biological samples. [ABSTRACT FROM AUTHOR]

In this paper, we propose and fabricate a kind of zigzag birefringent reflective metamaterial, the surface of which is a 1D rough surface. It can realize both multiple absorption and broadband polarization conversion at different frequency ranges of microwave. This metamaterial is made of a ring-shaped metal piece that is deposited on one side of a piece of grounded zigzag dielectric substrate. The absorptivities are 99.4% and 97.3% at 3.32 and 6.87 GHz respectively, and the polarization conversion ratio is more than 90% from 8.43 to 11.55 GHz, when the incident wave illuminates the sample with different polarization angles. A bifunctional device based on this metamaterial can act as either an absorber or a polarizer. This work is of significance to study the electromagnetic properties of rough surface metamaterials and provides an encouraging example in metamaterial design for combining different functions into one device. [ABSTRACT FROM AUTHOR]