Showing papers on "Hard-clad silica optical fiber published in 1983"

Beam-propagation analysis of loss in bent optical waveguides and fibers

Abstract: We demonstrate that the beam-propagation method can be used to calculate accurately both the pure bending loss and the transition loss of bent single-mode optical waveguides and fibers. Our results allow us to establish the accuracy of several commonly used theories of bending loss and to investigate the degree to which theories of step-index monomode fiber losses can be used to predict the losses of graded-index monomode fibers.

Optical fiber assembly with cladding light scattering means

Abstract: In an optical fiber assembly, an optical fiber having a core and a cladding is covered with a protecting film. The film is removed in a predetermined region extending from the end face of the optical fiber along the optical fiber, and the cladding is exposed. The surface of the exposed cladding is formed with a rough surface, and a laser beam which is transmitted to the cladding is scattered externally from the rough surface. The optical fiber is mounted on the hollow holder, and the rough surface of the cladding is disposed in the holder. The beam component scattered externally from the rough surface is absorbed by the light absorbing layer on the inner surface of the holder.

Optical fiber assembly and process for preparing same

Abstract: An optical fiber assembly comprising at least two plastic optical fibers and an embedding material, said plastic optical fibers being arranged substantially in parallel to each other and embedded in said embedding material, wherein each plastic optical fiber comprises a core of polymer having a refractive index, n 1 , and a cladding of a polymer having a refractive index, n 2 , wherein the refractive indices n 1 and n 2 satisfy the following relationship [I] n.sub.1 -n.sub.2 >0.01 [I] The optical fiber assembly is prepared by extruding from a spinneret a plurality of optical fibers having a core-cladding structure and an embedding material of a polymer in three layers of core, cladding and embedding material, according to a melt-spinning method; arranging the optical fibers in parallel to each other before solidification thereof; and bonding the optical fibers together through the embedding material.

Coupling monomode optical fiber having a tapered end portion

Abstract: A monomode optical transmission fiber with a tapered end portion. A lens is arranged on the end portion. The lens has a refractive index higher than that of the fiber core. Such a fiber has a substantially better coupling efficiency from a diode laser into the fiber core. The lens can be formed by immersing the tapered end portion of the fiber in a transparent liquid material. The drop formed on the end portion of the fiber after withdrawal from the liquid solidifies into a lens.

Method of and device for drawing an optical fiber from a solid preform consisting substantially of SiO2 and doped SiO2

Abstract: Optical fibres are drawn from a solid preform which consists substantially of SiO2 and doped SiO2. After leaving the heating zone, the fiber is guided through a space having a laminar gas flow to restrict the temperature drop across the fiber so that no extra stresses are incorporated in the fiber upon cooling. A device for performing this method comprises a quartz pipe through which the fiber is guided and in which a laminar gas flow is maintained.

Method for optical fiber fabrication including deuterium/hydrogen exchange

Abstract: A method for manufacturing silica-based optical fiber, and for manufacturing optical fiber preforms, the method comprising deuterium/hydrogen exchange in the silica-based material carried out subsequent to formation of the silica.

Optical fiber communication cables and method and apparatus for assembling same

Abstract: An individually armoured fiber optic core assembly (10) having a diameter not greater than 0.050" (1.72 mm) is provided as well as a process for making same. A fiber optic core (11) comprising a fiber optic element (12) and a surrounding protective layer (13) is encased within a drawn metal sheath (14) having a generally longitudinally extending seam (15). The ratio of the outside diameter of the fiber optic core (11) to the inside diameter of the metal sheath (14) is at least about 0.6:1. The fiber is formed by drawing metal strip (32') through a die (36) and simultaneously laying the core into the sheath as it is formed by the die. Optionally the sheath can be sealed by a line of solder applied along the length of the seam. Fiber optic cables comprising a plurality of individual fibers according to the invention are also described.

Method of making polarization preserving optical fiber

Abstract: A single-mode optical waveguide is constructed in a manner such that the core thereof is subjected to a stress-induced birefringence A single-mode optical fiber preform is formed by a CVD process A pair of longitudinally extending holes is formed on opposite sides of the core, spaced slighty therefrom A stress rod having a TCE different from that of the cladding portion of the preform is inserted into each hole The space between the holes and the rods is evacuated The resultant composite structure is drawn into an optical fiber A similar method is used to form a fiber having multiple light conducting cores, this method differing in that the rods which are inserted into the holes are formed of a glass having a refractive index greater than that of the cladding portion of the preform

Fabrication of single-mode fiber-type polarizer.

Abstract: A simple and novel fabrication technique for a fiber-type polarizer has been developed, and the polarization characteristics of the polarizer have been investigated. The polarizer is formed from a single-mode fiber composed of a concentric core and a silica cladding having a B(2)O(3)-doped silica portion. The cladding is etched off asymmetrically by utilizing the etching-speed difference between pure silica and B(2)O(3)-doped silica in 49% HF. The Al film is subsequently evaporated onto the etched portion. The extinction ratios of polarizers with various buffer-layer thicknesses were measured at two wavelengths, lambda = 1.15 pm and lambda = 1.29 microm. The maximum measured extinction ratio was 37 dB at lambda = 1.29 microm for a 4-cm-long polarizer.

Precise positioning of optical fibers

Abstract: Before splicing optical fibers (10) having cladding (12) and core (14) of differing refractive index, have their cores (14) axially aligned. The fiber ends (18, 20) are held apart with the fibers approximately coaxial. The fiber end surfaces (18, 20) are then illuminated and reflected light is monitored. Since reflectivity is a function of refractive index, the position of the core (14) in the reflectivity profile of each surface can be readily identified. The fiber ends (18, 20) can then be manoeuvred transverse of the fiber axes to bring the fiber core centers into registration with a datum line. The fiber ends are then brought close together for splicing. Previously, fibers having nominally identical outside diameters were aligned simply by pressing them into a common V groove (24), the optical transmission efficiency then depending on fiber/core concentricity. Alternatively, light was injected into the far end of one fiber, monitored at the far end of the other fiber, and the fibers at their near end manipulated to maximize monitored optical power. The present invention provides an easier and cheaper method of ensuring core alignment especially for monomode fibers.

Exposed core optical fibers, and method of making same

Abstract: The invention provides a method for making an optical fiber with a uniformly thin section of cladding. A preform having a core and at least one cladding layer is first made. The preform is prepared by cutting the preform so that the core is close to the surface of the preform. An optical fiber is pulled from the cut preform so the core is close to the surface of the optical fiber. The fiber may have cladding further removed by etching. A material selective etch may be used to make a protruding core fiber. Etching may be done on the preform before pulling the fiber.

Method of manufacturing a fiber-optical coupling element

Abstract: A method of manufacturing a fiber-optical coupling element by fusion of two monomode fibers. The fiber cores are made of a core glass, the American softening temperature of which is at least 80° C. higher than that of the cladding glass. The fibers are heated to a temperature between 520° and 560° C. By the method, fibers can be fused to form a coupling element without undesirable deformation of the fiber cores.

Low-loss single polarization fibers

Abstract: Low-loss single polarization fibers that maintain a state of linear polarization well are proposed. This fiber is composed of four regions: the concentric circular GeO2- and/or P2O5-doped core and pure silica clad regions for constructing the low-loss waveguide, and the B2O3-doped elliptical-jacket and the silica outer support regions for introducing the large nonsymmetric stress in the core. Theoretical and experimental studies on the coupling length of the two fundamental modes of orthogonal polarization and transmission loss have been carried out. An extinction ratio of less than −33 dB at 1-km fiber length and a loss of <0.8 dB/km at 1.5 μm were achieved.

Signal coupler for buffered optical fibers

Abstract: A signal coupler for buffered optical fibers comprises a soft, transparent, polymeric rod against which the fiber is pressed by a rigid "key" having regularly spaced protrusions which induce periodic microbending of the fiber. An optical signal passing down the fiber may be coupled into the polymeric rod by the key pressing the fiber into the rod, and the signal extracted from the end of the rod. A similar process may be used to inject an optical signal into the fiber. The coupler may be used either as a termination for a fiber or as part of a non-destructive tap. The induced attenuation and the intensity of the extracted signal may be varied by varying the pressure on the key.

Reduction of Impurities in Fluoride Glass Optical Fiber

Abstract: A sublimation purification technique was developed for fluoride fiber materials, ZrF4, BaF2, GdF3, and AlF3 Using these purified materials and a "build-in casting" method, the low-transmission-loss of 85 dB/km at 212 µm was o btained, which is the lowest loss in an infrared ray transmitting fluoride glass fiber The impurity level of the fiber was estimated as below 05 ppm by loss-factor analysis

Coated optical fiber cable structure which prevents longitudinal cracks

Abstract: There is disclosed a coated optical fiber having a buffer layer around the outer periphery of an optical fiber. A curable resin reinforced coated layer made of reinforced fiber materials is disposed around the outer periphery of the buffer layer and a heatcurable resin is impregnated to the materials and cured. A curable resin layer having no fiber material is interposed between the buffer layer and the reinforced coated layer. The reinforced layer includes therein a multiplicity of elongated fiber materials.

Treatment of glass for optical fiber

Abstract: PURPOSE:To improve the radiation resistance of quartz glass for an optical fiber by exposing the glass to an atmosphere contg. hydrogen to bond hydrogen only to defects in the glass and to introduce a proper number of OH groups. CONSTITUTION:Glass for an optical fiber such as a molded body of quartz glass soot forming a porous glass base material for an optical fiber, a molded body of quartz glass forming a transparent glass base material for an optical fiber or a molded body of glass forming an optical fiber is exposed to an atmosphere contg. hydrogen to bond hydrogen only to defects in the glass and to introduce the irreducible minimum number of OH groups required. Thus, an optical fiber enduring a radiation environment is obtd.

Method for fabricating an optical fiber cable

Abstract: There is disclosed a method for fabricating an undersea communications cable containing optical fibers. The cable is fabricated so that fiber optical loss characteristics vary only slightly with changes in strain in the cable. During fabrication an adhesive bonds the cable core containing the optical fibers to a layer of steel wire for preventing creep therebetween.

Coating material for optical communication glass fibers and fibers made therefrom

Abstract: A silicone coating material of a vinyl containing polyorganosiloxane, a polyorganohydrogensiloxane, a platinum catalyst, and an amorphous silica powder with a primary particle size of less than 0.2 μm is used to make optical communication glass fiber which has a cross-sectional structure of glass fiber core, a layer of the cured silicone coating material, and the exterior of the silicone coating material being covered with a thermoplastic resin material. The optical communication glass fiber made in this manner has a peelable coating such that the silicone coating material can be stripped from the glass fiber core.

Optical fibers with plastic core and polymer cladding

Abstract: Described are optical fibers having a core of plastic material, such as polystyrene, and a polymer covering of vinyl acetate or a fluorine-containing derivative of vinyl acetate, and a process for producing the same by drawing a bar of the same materials.

Ruggedized grated optical fiber

Abstract: A ruggedized grated optical fiber is described. The gratings in the fiber permit its use as a reflector or an interferometer when pairs of gratings having the same reflectance characteristics are spaced along the optical fiber. The ruggedized fiber comprises an optical fiber having the outer cladding removed down to an inner sheathing wherein a portion of the inner sheathing is further removed to expose the core wherein evanescent waves are encountered. The gratings are formed in this core. Surrounding the gratings and connected to the inner sheathing are two semi-tubular sections which are affixed to the inner sheathing and hermetically sealed around the gratings.

Reinforced optical fiber cable with glass or silica core

Abstract: A reinforced optical fiber cable comprises (i) an optical filamentary material with a glass or silica core and a lower index of refraction sheath, (ii) a reinforcement comprising at least two polymeric fibers having an elastic modulus above 10,000,000 psi, said fibers being held under tension .[.separate from one another.]. .Iadd.around the sheath .Iaddend.and positioned substantially parallel to the longitudinal axis of the core with substantially zero twist and (iii) a jacket which holds the reinforcement under tension.

Optical fibers having a fluoride glass cladding and method of making

Abstract: Fluoride glass cladded optical fibers are produced by rotationally casting a fluoride glass cladding tube, introducing core glass melt therein to form a preform, and drawing the preform into a fiber. Disclosed are methods whereby the process may be adopted to the production of multimode, stepped index profile waveguides, single mode waveguides, and waveguides having parabolic index profiles.

Optical cable element

Abstract: An optical cable element having a core and one or more optical fibers. The optical fibers may be provided with a separate secondary coating. The optical fiber or the secondary coating is connected to the core by a permanently elastic adhesive.

Optical multiple fiber

Abstract: An optical multiple fiber comprising a multiplicity of optical fibers which are fused together with each other, each optical fiber comprising a core made of pure silica glass and a cladding layer disposed on the core and made of a dopant-containing silica glass, characterized in that the thickness of the cladding layer satisfies the following equation (I): 2 D.sub.1 ≧T.sub.1 ≧1.0 μm. (I) wheren T1 is the thickness of the cladding layer in μm. and D1 is the outer diameter of the core in μm., in order to improve the image-transmitting capacity of the multiple fiber, including the sharpness and brightness of transmitted image.

Process for manufacturing glass fiber optical waveguides

Abstract: In the manufacture of optical fiber having a core of a core material and a cladding of a cladding material by drawing the fiber from an optical glass preform, the preform is manufactured by reacting a first plurality of initial reactants in their vapor state to obtan core material particles, by producing a coherent core body from the core material particles, by reacting a second plurality of initial reactants in their vapor state to obtain cladding material particles, by providing a coherent porous cladding on the core body from the cladding material particles, and by sintering the resulting composite body to convert the same into the preform. The core body can either be sintered before combining the same with the porous cladding material, or it may remain in its initial porous state until the sintering of the composite body. The core body may be produced by compressing the core material particles, either in a rigid mold by applying axial pressure in the radially inward directions to the flexible mold and through the same to the material confined therein. A similar approach can also be used with respect to the formation of the cladding body, except that the core body will now be centrically arranged in the mold cavity and hence the cladding body will be compressed around the same. However, the core body or the cladding body can also be produced from a firm body of the respective material, by being shaped from such firm body.

Optical fiber with embedded metal layer

Abstract: Selected portions of the interior surface of a substrate tube, or of the cladding or core layers deposited on the interior surface of the substrate tube, are treated by one or more process steps such as shaping, diffusing, leaching, or depositing. Patterning processes such as photolithography and lift-off are employed to define the selected portions. The resulting core and/or cladding layers of the fiber can be made to have a variety of geometric shapes and composition profiles useful, for example, in realizing birefringent fibers and multiple-core fibers. Also described is the similar treating of metal layers and the incorporation of such layers into the fiber.

Large bandwidth optical fibers

Abstract: Multimode optical fibers are described comprising a cylindrical core with a radius a o exhibiting an index of refraction n o surrounded by a cladding having an outer radius a in which the index of refraction varies continually from the core to the periphery from a value of n 1 to a lower value n e . Between the core and cladding there is a step change Δn in their respective indices of refraction whose value is a function of the ratio a o /a. Such fibers have both slight attenuation and slight dispersion and can be manufactured using processes similar to those used in making step-index optical fibers.

Studies on high-tensile proof tests of optical fibers

Abstract: By conducting high-tensile proof tests on optical fibers in order to eliminate weak points such as cracks or flaws, fiber strength is improved, but fiber length becomes shorter because of fiber breakage during proof tests. When the application is for submarine optical-fiber on cables, the upper limit of proof-test strain is determined based on theoretical and experimental studies on fiber strength and fiber length after proof tests.

Laser sizing method and apparatus for fiber optic buffers

Abstract: A system for machining and sizing optical fibers is described herein. The system uses a laser beam to machine oversized regions of a buffer material surrounding an optical fiber to create a coated optical fiber having a substantially uniform maximum outer dimension that is within a desired tolerance specification. The machining of the buffer material to size the optical fiber is accomplished by generating at least one laser beam transverse to the buffer material, rotating the beam or beams about an axis coaxial with the optical axis of the optical fiber, and moving the fiber past the rotating laser beam or beams. The rotating laser beam or beams vaporize any excess or oversized regions of buffer material and substantially provide the optical fiber with the desired outer dimension or diameter.