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Optical fiber magnetic field sensor based on birefringence in liquid core optical waveguide
摘要： An optical fiber magnetic field sensor based on the birefringence of magnetic fluid is proposed by filling the magnetic fluid into a hollow-core waveguide. The birefringence characteristics of magnetic fluids with different concentrations tuned by magnetic field were investigated under different magnetic fields when the filled hollow-core waveguide is placed in a Sagnac loop. As the magnetic field increases, the internal chain-like structure of the magnetic fluid increases, resulting in changes in birefringence. The experimental results show that the device has a highly linear response to the variation of magnetic field intensity in the range of 0–300 Oe with the maximum sensitivity of 29.2 pm/Oe and resolution of 0.68 Oe. The proposed magnetic field sensor has such advantages as ease of fabrication, simple structure, low cost and it is expected to find potential applications in the magnetic field measurement with high accuracy, optical fiber gyroscopes, magneto-optic modulators and so on. Due to the external field tunability, the device also provides a promising technology for microfluidics research.
关键词： Birefringence,Optofluidic in fiber,Magnetooptic effects,Optical fiber devices
更新于2025-11-28 14:24:03
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Fiber optic birefringence enhanced accelerometer based on polarized modal interferometer
摘要： An inline fiber optic birefringence enhanced accelerometer (FOBEA) which applies one polarizer and a ten-meter high birefringence fiber wrapped on a transducer cylinder is proposed. Birefringence of polarized modes in panda polarization maintaining fiber (PMF) is enhanced by fiber coating and cylinders of different parameters. Accelerometers with copper cylinder (FOBEA-1) and polyurethane cylinder (FOBEA-2) are fabricated, the tested average sensitivities are 1.06rad/g (20-3800 Hz) and 16.97 rad/g (20-2000 Hz). The experimental results show the birefringence gain of FOBEA-1 is in good consistent with theoretical calculation of 1.07 and an additional birefringence gain of FOBEA-2 is 5.52 because the polyurethane cylinder works as fiber coating with the thickness of 1.21 mm. Temperature crosstalk is also investigated.
关键词： Polarized modal interferometer,Fiber optic accelerometer,Sensitivity,Transducer cylinder,Birefringence gain
更新于2025-11-28 14:23:57
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From colloidal CdSe quantum dots to microscale optically anisotropic supercrystals through bottom-up self-assembly
摘要： The development of fabrication techniques for novel nanostructured materials is one of the key tasks of modern materials science. One pathway to successfully complete this task is the bottom-up assembly of colloidal nanoparticles into ordered superstructures, possessing both the properties of individual nanoparticles and further novel properties resulting from their interactions. However, nanoparticle self-assembly depends on a variety of parameters, which makes the precise control of this process a complicated problem. Here, the time course of quantum dot (QD) self-assembly into ordered superstructures has been analyzed, along with the evolution of their morphological and optical properties. QD self-assembly occurs through two distinct stages (homo- and hetero-geneous), leading to the formation of supercrystals with a layered morphology. Analysis of the optical properties throughout the superstructures’ growth has shown that the absorption and photoluminescence (PL) bands are blue shifted, retaining almost the same PL lifetimes as in the initial QD solution. The supercrystals formed possess a further unique optical property caused by their layered morphology; namely, a four-fold symmetry characterized by strong birefringence. Such supercrystals may be used for the fabrication of microscale optical paths with high extinction coefficients and specific polarization properties for novel optoelectronic devices.
关键词： optical anisotropy,nanostructured materials,birefringence,self-assembly,quantum dots,supercrystals
更新于2025-11-21 11:08:12
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An optical test to unveil twisting of birefringent crystals in spherulites
摘要： Helical conformations and structures are frequently observed in materials. The presence of helices at points of the unit cell of a crystal, on a larger size scale in the crystalline lattice or even in the microscopic structure of crystals, affects the chemico-physical properties of a solid and, hence, also interactions with light. Here, attention has been drawn to the geometrical properties of helices produced by a hypothetical torque of a transparent crystal, and optical properties of twisted crystals easily observed by a polarizing microscope have been discussed. Radially grown spherulites are obtained by most substances crystallized from melt. The circular optical arrangement of behaviour of larger dimensions of spherulites, allows investigations otherwise hardly feasible on separate crystals. According to the torsional analysis of elongated bodies and the birefringence theory, information on the existence of helically shaped crystals can be deduced, as hereinafter explained, from the microscopic appearance and birefringence pattern of spherulites. Indeed, twisting decreases the birefringence throughout an elongated crystal and, therefore, also the birefringence of spherulites formed by twisted radial crystals is reduced.
关键词： optical microscopy,microstructure,helical deformation,birefringence,crystals,banding
更新于2025-10-24 16:38:51
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Orientation-Dependent THz Response of <i>m</i> -Plane Sapphire Substrate by Polarization-Sensitive THz Time Domain Spectroscopy
摘要： The dielectric response of m-plane sapphire (m-sapphire) substrates in the terahertz (THz) frequency is investigated using polarized-sensitive femto-second THz time-domain spectroscopy. We examined the transmitted THz time-domain waveforms with respect to the parallel-polarized THz field by rotating phi angle of m-sapphire substrates. The THz amplitude significantly decreased at the azimuth angle of 0°, 90°, and 180° with roughly equal amplitudes and no propagation time delay. The time delay of 480 fs in the THz pulse oscillations was observed between the azimuth angle of 45° and 90°, possibly due to the birefringence of nonpolar m-sapphire substrate. Strong THz field absorptions around ～1 THz frequency at azimuth angles of every 90° could be attributed to low-frequency phonon modes.
关键词： Sapphire,Birefringence,Time-Domain Spectroscopy,THz
更新于2025-09-23 15:23:52
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On investigations of refractive indices and birefringence of fiber using duplicate and non-duplicate micro-interferograms of double refracting interferometer
摘要： The formula of refractive index of fiber considering the refraction has been reviewed. This formula is used to investigate the effect of refraction on the accuracy of refractive index calculations with different simulated micro-interferograms of duplicate interference fringes with different fringe shifts order. Also a more accurate formula to calculate the birefringence from the non-duplicate interference fringes has been derived and tested to calculate the birefringence of simulated and experiment micro-interferogram. The presented micro-interferograms were automatically analyzed and the contour lines of the bright fringes were determined using Fourier transform technique. A prepared software program takes the contour line of the fringes and automatically calculate the refractive index, the radius, and the birefringence of fiber. A good result was obtained in case of using immersion liquid matches between the parallel and perpendicular refractive indices of fiber.
关键词： image analysis,refractive index profile,interferometry,birefringence of fiber
更新于2025-09-23 15:23:52
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Interferometric investigation of the opto-mechanical and structural properties of iPP/TiO <sub/>2</sub> nanocomposite fibers
摘要： Fibers that missing specific features and functionalities could be innovated and functionalised via nano additives, in particular metal oxides. Titanium oxide (TiO2) nanoparticles have been added to isotactic polypropylene (iPP) to form iPP/TiO2 nanocomposite fibers. Three samples of iPP/TiO2 fibers were extruded at three extrusion speeds 25, 50, and 78 m/min were considered in this study. Mach–Zehnder interferometer was used to assess the changes in the opto-mechanical and geometrical parameters of iPP/TiO2 nanocomposite fibers along the fiber axis. The mechanical drawing device along with Mach–Zehnder interferometer was utilized to stretch the filaments to different draw ratios. The effect of mechanical cold drawing and extrusion speed on the optical and physical characteristics of iPP/TiO2 nanocomposite fibers were determined along the fiber axis. The optical and physical variation along the nanocomposite samples were characterized by measuring their refractive indices, birefringence, refractive index profile along the fiber axis. The diffraction of He–Ne laser beam was used to define the variation of the fiber diameter along the fiber axis through their cross-sectional area and shape. A sample of uniform diameter from neat iPP fibers was used as reference material for studying the variation of the iPP/TiO2 fiber diameter along the fiber axis. As result, the iPP/TiO2 nanocomposite fibers exhibited nonuniform diameters. The dispersion of TiO2 particles in nanocomposite fibers influences the properties' consistency along and across the fiber.
关键词： cold drawing,nanocomposites,birefringence,interferometry,polypropylene fibers
更新于2025-09-23 15:23:52
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A nonlinear photonic crystal fiber for liquid sensing application with high birefringence and low confinement loss
摘要： This paper presents a nonlinear Photonic Crystal Fiber (PCF) based sensor to detect liquid analytes. An extensive analysis has been presented at wide range of wavelength (0.6 μm?1.6 μm) in order to investigate the impact of some design parameters. The numerical investigation has been done using the full vector Finite Element Method (FEM). The proposed model provides an outstanding nonlinear coefficient value with high birefringence, high sensitivity, and low confinement loss. The designed model can be used in sensing and bio-sensing research and their applications.
关键词： Effective Area,Sensitivity,Nonlinearity,Confinement loss,Photonic Crystal Fiber,Birefringence
更新于2025-09-23 15:23:52
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Photoelastic birefringence of copolymers with non-planar structure
摘要： We demonstrate the utility of nonplanar building blocks to tune the polymer photoelastic birefringence and obtain near zero and negative photoelastic coefficients. Photoelastic properties of two novel random copolymers systems: 2-vinlypyridene (2VP)-hydroxyadmantyl methacrylate (HAMA) and vinyl pyrrollidone (VP)-isobornylacrylate (iBOA) were investigated at a function of comonomer composition. Photoelastic coefficient of the copolymers could be facilely tuned by changing the copolymer composition. In particular, we show that negative stress optic coefficient could be obtained from VP - iBOA copolymers and near zero stress optic coefficient could be obtained from 2VP -HAMA copolymers. In addition, we investigate the effect of addition of triethylene glycol (TEG) as a plasticizer on the photoelastic properties for the 2VP-HAMA copolymers. We found that addition of TEG led to a reduction in both the polymer Tg and photoelastic coefficient. Our study indicates that bulky non-planar side groups in the polymer backbone tend to induce negative photoelastic birefringence and can be utilized as important building blocks for the design of optical polymers.
关键词： Optical polymers,Photoelasticity,Birefringence
更新于2025-09-23 15:23:52
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Simultaneously achieving a large negative dispersion and a high birefringence over Er and Tm dual gain bands in a square lattice photonic crystal fiber
摘要： We proposed a novel photonic crystal fiber composed of a double-cladding square lattice that could be used in dual-band, Er and Tm optical gain bands, simultaneously supporting a large negative dispersion and a high birefringence. We theoretically investigated the light guiding property through the proposed PCF by using a vectorial finite element method (FEM) with a perfectly matched layer (PML). By optimizing the structural parameters, we obtained an ultra-large negative dispersion of -20,186ps/(nm?km) and a very high birefringence of 9.27 ×10-3 at the wavelength of 1.55μm in the Er gain band and a very large negative dispersion of -8,067ps/(nm?km) and a high birefringence of 1.0 ×10-3 at the wavelength of 1.87μm in the Tm band. We further discussed the roles of waveguide parameters on the chromatic dispersion, its slope, and the birefringence of the fiber as well as the mode field diameter. The proposed fiber could be directly applied for dual-band dispersion and polarization control in fiber laser cavities as well as optical communications and sensors in the dual bands.
关键词： Thulium band,Erbium band,Negative dispersion,High birefringence,Photonic crystal fiber
更新于2025-09-23 15:22:29