Surface Analysis and Treatment of Extruded Fluoride Phosphate Glass Preforms for Optical Fiber Fabrication

Fabrication of fluoride phosphate glass optical fibers using the extrusion method for preform fabrication has been studied using the commercial Schott N‐FK51A glass. The extrusion step was found to create a surface layer of differing composition from the bulk glass material, leading to defects drawn down onto the optical fiber surface during fiber fabrication, resulting in high loss and fragile fibers. Similar phenomena have also been observed in other fluoride‐based glasses. Removal of this surface layer from preforms prior to fiber drawing was shown to improve optical fiber loss from >5 dB/m to 0.5–1.0 dB/m. The removal of this surface layer is therefore necessary to produce low‐loss fluoride phosphate optical fibers.     

Fabrication of Arsenic Sulfide Optical Fiber with Low Hydrogen Impurities

Arsenic sulfide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of tellurium tetrachloride (TeCl₄) to the glass. During melting, the chlorine from TeCl₄ reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to produce optical fibers with significantly reduced loss due to hydrogen sulfide impurity content (1.5 dB/m).     

Fabrication of Arsenic Selenide Optical Fiber with Low Hydrogen Impurities

Arsenic selenide glass optical fibers typically possess extrinsic absorption bands in the infrared wavelength region associated with residual hydrogen and oxygen related impurities, despite using purified precursors. We report a purification process based on the addition of 0.1 wt% tellurium tetrachloride (TeCl₄) to the glass. During melting, the chlorine from TeCl₄ reacts with the hydrogen impurities to produce volatile products (e.g., HCl) that can be removed by subsequent dynamic distillation. The processing conditions have been modified accordingly to give very low H–Se impurity content. Consequently, the H–Se absorption band centered at 4.57 μm has been reduced from tens of dB/m to 0.2 dB/m.     

Reversible Optical Density Changes in Composite Layers

Selected phototropic Ag-halide-containing glasses were heat-treated and then centrifuged at high temperatures to eliminate the phase-separated carriers of phototropy. Analyses of the sediment showed, in addition to Ag and halide ions, at least one additional component. On the basis of the results of the analyses, such ternary systems and similar related compositions were vapor-deposited onto substrates. The resulting layers, 150 to 570 nm thick, were studied for phototropism. The best phototropic properties were achieved in the eutectic area of the ternary system Ag-Br-Cu.     

Optimization of Compressed Ceramics Fiber Insulating Layers

Compressed thin layers of ceramic fiber insulation are used as high temperature insulating layers as well as mechanical support for catalyst coated ceramic monoliths in automotive emission control devices.Minimization of energy losses,choice of material and thickness of compressed insulating layer are based on knowledge of their thermal physical properties.Currently,consistent measurements of materials in a compressed state, as they would be in emission control applications,are absent due to the absence of suitable methods for such tests.A test method was developed for measurement of the thermal conductivity of compressed thin fiber layers.This paper summarizes the results of thermal conductivity and diffusivity measurements of 27 compressed fiber alumina- silica- vermiculite materials in the range of 200- 950 ℃.Thermal physical properties as a function of temperature,density / mechanical pressure,thickness and composition of insulating layers are presented.The whole set of experimental data is generalized on 3D surface plots and described by polynomial functions.The possible heat transfer mechanisms governing apparent thermal conductivity of pressed insulation layers are discussed.     

Measurement of Gas Transport through Fiber Preforms and Densified Composites for Chemical Vapor Infiltration

Gas transport via pressure-driven permeation or via concentration-driven diffusion is a key step in the chemical vapor infiltration (CVI) process. This paper describes methods for the measurement of these properties for CVI preforms and partially infiltrated composites. Results are presented for Nicalon-fiber cloth layup preforms and composites, Nextel-fiber braid preforms and composites, and a Nicalon-fiber three-dimensional (3-D) weave composite. The permeability of Nicalon cloth layup preforms is strongly dependent on the packing density over the range of 29-40 vol% but is only weakly dependent on the orientation of the alternating cloth layers. The specimen-to-specimen variation is high (standard deviation of 20%), which reflects the statistical nature of the interlayer separation and alignment. This variability also affects the results for the partially densified specimens, where the permeability values for specimens of similar density can be very different. Trends in the diffusion factor results are similar to those for permeability, which reflects the fact that both transport parameters are dependent on the structure of the same pore network, although in somewhat different ways. The permeability of Nextel braid preforms is dependent on the thread count and the weight for cloths with similar construction and packing density. The gas permeability of the finer wave (6.3 tows/cm (16 tows/in.)) is approximately one-half that of the coarser weave (3.5 tows/cm (9 tows/in.)). Results are reported for a small number of infiltrated composites with Nextel fiber reinforcement. Attempts to mount a Nicalon-fiber 3-D weave preform specimen have been unsuccessful. Results for a small number of composite specimens with 3-D weave reinforcement are reported.     

Fabrication of Fine YAG-Particulate-Dispersed Alumina Fiber

This paper involves novel fabrication processes for polycrystalline α-Al₂O₃-matrix composite fibers that contain nanosized yttrium aluminum garnet (YAG) particles. Dense α-Al₂O₃/YAG nanocomposite fibers with a fine and homogeneous microstructure can be successfully fabricated via a modified sol-gel process and α-Al₂O₃ seed-particle addition. YAG nanoparticles have been homogeneously dispersed within Al₂O₃-matrix grains as well as at grain boundaries. Effects of α-Al₂O₃ seed particles and YAG nanodispersions on crystallization and microstructure development of nanocomposite fibers are discussed.     

Effect of Fiber Drawing Tension on Optical and Mechanical Properties of Optical Fiber Waveguides

Based on experimental results, the effects of fiber drawing tension on both optical and mechanical properties of optical fibers are discussed. Lower drawing tensions (i.e. > 0.05 N (5 g)) were found to be desirable for fabricating uniform high-strength fibers, whereas higher drawing tensions (i.e. > 0.5 N (50 g)) were better for low-loss fibers having a large silica core.     

塑料光纤的研制

采用四氟烷基醇为主要单体,合成聚甲基丙烯酸四氟烷基酯,并以此作为光纤鞘材,以聚甲基丙烯酸甲酯(PMMA)为芯材,制成PMMA/含氟树脂型塑料光纤。还介绍了该光纤的主要性能     

Materials Development of Optical Fiber

Traditionally, new materials are developed in response to the requirements of an emerging device technology. In the optical fiber case, development of glass as a transmission medium came as the culmination of a century-long quest for improved broadband telecommunications, a search that established the superiority of light signals transmitted through glass over electronic signals transmitted by wire.     

Fatigue Weakening of Optical Fiber

The weakening of optical fiber under static strain was measured in water and as a funetion of time in air. The weakening did not fit the crack-growth model of fatigue nor did it follow the same path in air and water. However, the size of the H₂O/D₂O isotope effect suggested that fatigue could still result from a silica-water reaction.     

Use of Electrophoretic Impregnation and Vacuum Bagging to Impregnate SiC Powder into SiC Fiber Preforms

Techniques based on vacuum bagging (VB) and electrophoretic impregnation (EPI) have been investigated for the impregnation of SiC powder into layered Nicalon SiC fabric preforms. The aim was to produce preimpregnated samples for subsequent chemical vapor infiltration (CVI) with reduced intertow porosity that arises from the construction of the fabric layers while leaving unblocked the intratow porosity that is so indispensable for a successful infiltration. Because the goal was simply to learn about the ability to impregnate the samples, no interphase coating was applied to the fibers as would normally be used when producing SiC_f/SiC composites. While the VB process generally yielded much stronger preforms, depending on the pressure used and the powder particle size, it resulted in powder becoming located in the intratow rather than the intertow porosity. In contrast, provided an appropriate electrode arrangement was used, EPI offered the potential for a more controlled impregnation process with the powder primarily found in the intertow porosity; however, the preforms were very weak and delaminated easily. The combination of the two processes resulted in a very successful approach, with greater uniformity of particle infiltration and higher green strengths, while largely avoiding impregnating the intratow porosity.     

塑料光导纤维研究进展

塑料光导纤维（ＰＯＦ）具有模量低、直径大、柔韧性好等优点,已经在当今信息社会获得广泛应用。介绍了塑料光导纤维的优点、性能及研究进展,并展望其发展方向。     

冗余光纤环网在玻璃生产中的应用

介绍了玻璃生产线应用的一种全新的总线网络形式———冗余光纤环网。首先建设光纤骨干网路,然后将现场信号转变为光信号接入该网路,最后传输至DCS系统处理。这种设计大大简化了目前繁琐的控制方式及通讯方式,具有速度快、容量大、不易受电磁干扰、可靠性高等特点。     

Fabrication of Thin Oriented Organic Layers and Micropatterns by Zone Casting

Zone casting—a special solution processing method for obtaining highly ordered continuous layers of soluble organic materials—can also be applied for fabricating patterned layers. In this method, solution is continuously supplied onto a substrate that is withdrawn at a controlled rate, and the solvent evaporates from the surface of a meniscus formed between a flat nozzle and the substrate. Due to the gradient of a solute concentration, its solidification proceeds within the narrow zone localized in the meniscus. In this way solute molecules can be self-assembled at surfaces into different anisotropic nanostructures (columns, rods, lamellae, or microcrystals) uniaxially aligned parallel to the substrate. Under some conditions various phenomena like dewetting, fingering instability, stick-slip motion, etc., come into play, leading to various periodic perturbations in the film deposition. Examples of continuous and patterned layers of different materials such as low molecular weight (semi)conductors, chromophores, discotic molecules, and block copolymers, which can successfully be processed using this technique, are shown. Typical layers obtained through this method are shown to have good properties as active layers in field effect transistors.     

Fabrication of Low-Temperature Co-Fired Ceramics Micro-Fluidic Devices Using Sacrificial Carbon Layers

Ease of fabrication and design flexibility are two attractive features of low-temperature co-fired ceramics (LTCC) technology for fabrication of complex micro-fluidic devices. Such structures are designed and processed using different shaping methods, the extent and complexity of which depends on the final device specifications (dimensions, and mechanical and functional properties). In this work, we propose a sacrificial layer method based on carbon-black paste, which burns out during the LTCC firing stage. The article will summarize the preparation of the paste, influence of processing conditions on the final dimensions, and demonstrate the mechanically integrated structures obtained using this technique. Some of these are membranes of various diameters (7–12 mm) with a thickness of 40 μm and a variety of internal spacing (15–60 μm), free-hanging thick-film resistor bridges on LTCC for heating micro-volumes. The main methods of the study will be thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and dilatometry in addition to electronic instruments for device characterization.     

光纤连接器制备技术的进展

从光纤连接器的发展历程,光纤连接器套管的结构、加工技术,材料体系及其性能特点,论述了光纤连接器的研究、制备技术现状及发展趋势.     

微型光纤光谱仪在材料老化研究中的应用

本文简要介绍了颜色测量的理论基础和交叉Czerny—Turner式分光结构光纤光谱仪的工作原理;概述了光谱仪在老化含能材料中的应用。利用微型光纤光谱仪对材料在老化过程中的表面颜色变化进行定量化分析,得到的结果表明：微型光纤光谱仪可为含能材料的老化研究提供更客观和科学的依据。     

Fabrication of Titanium Carbide-Alumina Composites by Combustion Synthesis and Subsequent Dynamic Consolidation

Dispersed-phase composites of TiC-Al₂O₃ were fabricated from low-cost reactants by external ignition of powder compacts followed by dynamic consolidation of the hot products using explosives. Near full densification was achieved using shock pressures as low as 1 GPa. Care must be taken to allow for the escape of evoled gases during exothermic reaction, and rapid cooling of the consolidated composite must be avoided to prevent cracking.     

光纤通信中光孤波间相互作用研究综述

光孤子通信系统是一种数字通信系统,由于光孤子具有保形传输的特性,人们自然会想到通过减小相邻孤子间距的办法来达到增加通信系统容量的目的。因此,研究孤子间互作用及其抑制方法,对通信系统容量的提高,具有极大的理论参考与实用价值。