Papers by Keyword: Birefringence

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Authors: Yu Wei Sun, Yu Kun Bai
Abstract: A dual-core photonic crystal fiber (PCF) with high birefringence, short coupling length and broadband flat dispersion is proposed in the paper. The symmetry of the original symmetric structure composed of hexagonally distributed air holes is distorted by replacing the innermost 12 air holes with 6 elliptical air holes. The characteristics of the dual-core PCF such as birefringence, coupling length and chromatic dispersion are analyzed by tuning its structural parameters. The results demonstrated that the dual-core PCF exhibits simultaneously a birefringence of up to 10-2, a coupling length of 68.178 for the x-polarization and 74.825 for the y-polarization, and a broadband flat dispersion ranging from 1.1 to 1.6. The novel dual-core PCF may find applications in polarization-maintaining fibers and fiber-based polarization beam splitters/couplers with broadband flat dispersion.
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Authors: Jian Hui Zeng, Xu You Li, Wen Bin H
Abstract: A novel high-birefringent photonic crystal fiber (PCF) was proposed and analyzed by full-vector finite element method (FEM). The modal field and birefringence properties were investigated. All of air holes in proposed PCF are round, and their diameters are the same. It is greatly reduce the difficulty of fabrication. According to the results of numerical analysis, it can be observed that the mode birefringence of this novel PCF can be easily achieve the order of 10-3 at 1.55μm. This research provides effective theoretical method for the fabrication, development and construction of high-birefringence photonic crystal fiber.
185
Authors: Jong Sun Kim, Chul Jin Hwang, Kyung Hwan Yoon
Abstract: Recently, injection molded plastic optical products are widely used in many fields, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique to measure the birefringence in transparent injection-molded optical plastic parts using two methods as follows: (i) the two colored laser method, (ii) the R-G-B separation method of white light. The main idea of both methods came from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. The comparison between two methods is demonstrated for the same sample of which retardation is up to 850 nm.
187
Authors: M. Ramakrishna Nanachara Rao, P.V. Datta Prasad, V.G.K.M. Pisipati, D. Madhavi Latha
Abstract: Refractive indices measurements are carried out in four alkoxy benzylidene anilines viz., N-(p-n-methoxy and ethoxy benzaldehyde)-p-n-dodecyl and tetra decyl anilines, 1O.12, 1O.14, 2O.12 and 2O.14. First three compounds exhibit monovariant nematic phase while the last compound exhibits nematic and SmA phases with variable thermal ranges. The molecular polarizabilities are calculated from the refractive indices and the density using the well known internal field models by Vuks and Neugebauer. The molecular polarizability anisotropy is estimated from the Lippincott δ-function model as well as molecular vibrational methods. The order parameter is estimated using a) from the Haller’s extrapolation from molecular polarizabilities, b) from the scaling factors obtained from the equations by Vuks and Neugbeaur and c) directly from the birefringence - a method developed by Kuczynski et al without considering any internal field model to the liquid crystal molecule. The results evaluated from these methods are compared from one another and the limitations of the methods used are discussed.
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Authors: Hui Lan Liu, Ru Ya Li, Huai Yong Yu, Jun Jie Wang, Zhi Chao Jiao
Abstract: Resonance integrated optical gyroscope, Polarization-maintaining waveguide, Single-mode condition, Birefringence. Abstract. A polarization-maintaining (PM) waveguide used in Resonance Integrated Optical Gyro (RIOG) is theoretically proposed. Three essential factors determining the PM performance, which are the single-mode condition, birefringence and core index, are analyzed and optimized respectively. The single-mode rectangular waveguide is obtained by analyzing the propagation mode of the rectangular waveguide. A high birefringence waveguide design method is brought up according to the theory of geometrical birefringence, realized by changing the cross-sectional shape of the waveguide. The effect that the core index contributes to the birefringence is also discussed, and an optimal core index of the waveguide to reach maximal birefringence is determined in the condition of single-mode transmission. The high birefringence PM Waveguide with geometrical birefringence of 1.5×10-4 is obtained by theoretical analysis, the simulation results shows that the polarization cross-talk in RIOG is obviously improved.
156
Authors: Morten Kildemo, M.B. Mooney, P.V. Kelly, C. Sudre, G.M. Crean
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Authors: Wei Wang, Bo Yang, Hong Ru Song, Yue Fan
Abstract: A new type of photonic crystal fiber (PCF) with pentagonal air-core is proposed, which consists of octagonal air holes in the cladding. In addition, five elliptical air holes are embedded in the inner layer to enhance the birefringence characteristic. Characteristics of this PCF are analyzed by using of Finite Element Method (FEM). Numerical results show that this kind of PCF exhibits high birefringence with the level of 0.001 after optimization, which will find application in optical sensing systems.
586
Authors: Wei Wang, Bo Yang, Yue Fan, Hong Ru Song
Abstract: Aiming at the requirements of high performance of optical communication systems, a new type of photonic crystal fiber (PCF) is proposed. This kind of PCF consists of hexagonal air holes in the inner cladding and octagonal air holes in the others layers. Two big elliptical air holes are embedded to enhance the birefringence. Numeral results show that this kind of PCF exhibits high birefringence with the level of 10-3 and high nonlinearity with the level of 10-2m-1w-1. In addition, two zero dispersion points are obtained after optimization, which will find application in dispersion compensation PCFs.
326
Authors: Dong Hoon Kang, Chang Sun Hong, Chun Gon Kim
Abstract: Because of their good multiplexing capabilities, fiber Bragg grating (FBG) sensors are being studied more actively than any of other fiber optic sensors. The application fields of FBG sensors have been mainly focused on composite materials through embedding rather than through surface attachments. However, there are many limitations on the embedding of FBG sensors into composite materials because of the birefringence that is induced when FBG sensors are not embedded parallel to the reinforcing fibers. This study investigates the fabrication of FBG sensors that have various grating lengths, good multiplexing capabilities, better stability from birefringence, and ease in production. The signal characteristics of FBG sensors are also verified through the cure monitoring of two composite laminates.
152
Authors: George C. Wei
Abstract: The packing structure in green alumina bodies has been studied using thin sections of prefired bodies impregnated with refractive-index liquid examined with an automatic, polarizedlight microscope equipped with liquid-crystal adjustable quarter-wave plate and analyzer, and circularly polarized light. The combined intrinsic birefringence (caused by the anisotropy of the hexagonal symmetry of the alumina particles) and form birefringence (due to packing of the slightly elongated particles oriented in the green structure), can be quantified on a small scale. Birefringence values and slow-vibration directions are mapped for the anisotropic fine particles and agglomerates circumferentially or radially aligned in the structure. For some pre-sintered bodies, the interference pattern shows three radial dark brushes with relatively low birefringence, coming from the spider in the extruder. Slow-axis distribution shows random particle orientation in the spider region. The birefringence pattern often indicates a relatively high degree of circumferential alignment in the surface area where frictional force is present during forming. A uniform distribution of the birefringence represents a consistent green structure. The improved procedure for characterization of prefired body provides considerable insight to the optical crystallography of powder/particle arrangement in pre-sintered ceramic body and the relationship of the particle alignment with respect to flow and forming.
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