Abstract: The invention is a method of making an optical fiber or cane (600) that has optical properties that vary axially. Core glass (100) and clad glass (200) are fed into a furnace to form the cane or fiber. The velocities of the feeding of the clad and core are controlled so that the total combined mass per unit time is constant. The diameter of the core (604) varies along the length of the fiber or cane in accordance with the control of the velocities. The variance in the core diameter results in the variance of the axial optical properties of the fiber or cane.

Abstract: An optical fiber having optical characteristics that systematically vary along its length is made by inserting a plurality of cylindrical tablets into a cladding glass tube and overcladding the tube with particles of cladding glass. Each tablet contains a core region, and it optionally contains a layer of cladding glass Adjacent tablets are capable of forming optical fiber sections having different optical properties. Prior to consolidating the glass particles, chlorine flows through the tube and over the tablets. When the tube begins to sinter, the chlorine flow is stopped and the sintering particles generate an inwardly directed force that causes the tube to collapse inwardly onto the tablets which concurrently become fused to each other. The resultant draw blank can be drawn into a low loss optical fiber. This method is particularly useful for making dispersion managed single-mode optical fibers.

Abstract: The invention relates to apparatus for manufacturing an optical fiber preform from a tube of vitreous material, the apparatus comprising:

Abstract: The surface quality of halide, preferably fluoride, articles, e.g., articles used in the preparation of halide fibers is improved by cleaning the surface with an aqueous etchant and thereafter removing the etchant by washing the surface with methanol. The aqueous etchant is preferably a solution which contains hydrochloric acid and zirconium oxychloride.

Abstract: A method of making a segmented core optical waveguide preform for making fiber that is resistant to attenuation increases due to hydrogen and heat aging. A first core region comprising a silica glass rod containing at least a first dopant is inserted into a central opening of a second core region comprising silica soot containing a second dopant. The first core region and second core region are consolidated together to form a segmented core region and cladding is deposited on the outer surface of the segmented core region.

Abstract: An optical fiber having optical characteristics that vary along its length is made by assembling a plurality of cylindrical glass or soot tablets into or along a glass tablet alignment device, then fused into monolithic assembly. If desired, additional glass may be applied to the assembly before or after the fusing step. A vacuum is preferably applied during the fusing step. Each tablet preferably contains a core region, and it optionally contains a layer of cladding glass. Adjacent tablets are capable of forming optical fiber sections having different optical properties. Prior to consolidating the glass particles, chlorine preferably flows through or around the tablets and alignment device. The resultant draw blank can be drawn into a low loss optical fiber having short transition regions between adjacent areas of fiber. This method is particularly useful for making dispersion managed single-mode optical fibers.

Abstract: A singlemode optical fiber 700 having very low loss at 1385 nm, and a practical method for making same are disclosed. A core rod 20 is fabricated using vapor axial deposition to have a deposited cladding/core ratio (D/d) that is less than 7.5. The core rod is dehydrated in a chlorine- or fluorine-containing atmosphere at about 1200.degree. C. to reduce the amount of OH present to less than 0.8 parts per billion by weight, and then consolidated in a helium atmosphere at about 1500.degree. C. to convert the porous soot body into a glass. The consolidated core rod is elongated using an oxygen-hydrogen torch that creates a layer of OH ions on the surface of the rod that are largely removed by plasma etching. Finally, the core rod is installed in a glass tube 40 having a suitably low OH content. Thereafter, the tube is collapsed onto the rod to create a preform 60. Conventional methods are employed for drawing an optical fiber from the preform and applying one or more protective coatings 75, 76.

Abstract: A method for controlling a bore diameter of an optical fiber ferrule is disclosed. The diameter of the bore is controlled by collapsing the ferrule around a rod inserted in an over-sized bore formed therein. The diameter of the rod is selected to match the diameter of the optical fiber to be supported by the ferrule. Thus, after the rod is subsequently immersed in liquid nitrogen removed from the ferrule, the ferrule has a bore diameter which is defined by the diameter of the rod. Suitable materials for the ferrule and the rod include glass and metal, respectively.

Abstract: A large optical preform 303 is made by a modified chemical vapor deposition (MCVD) process by depositing successive layers of core and cladding materials onto the inside surface of a rotating glass tube 33 having a hydroxyl ion (OH.sup.-) level that is less than 0.5 parts per million (ppm) by weight. The tube is then collapsed inwardly to form a core rod 301 in which the deposited core material 31 has a diameter that is greater than about 5 millimeters and the deposited cladding material 32 has an outside diameter that is less than about 15 millimeters. A machine-vision system 140, 150, 160 monitors and controls the diameter of the glass tube by regulating the pressure within the tube. Moreover, the machine-vision system monitors and controls the straightness of the tube by varying its rotational speed according to angular position. After the core rod 301 is formed, it is plasma etched to remove contaminants, and then overclad with two glass jackets 34, 35 having a hydroxyl ion (OH.sup.

Abstract: The present invention relates to a single-mode optical fiber having a configuration which enables lowering of dispersion slope while securing a sufficient MFD. This single-mode optical fiber has a refractive index profile in which an indent with a sufficient width is provided at the center of its core region. In particular, this indent satisfies the following relationship:a.multidot.(.DELTA.n.sub.2 -.DELTA.n.sub.1)/(b.multidot..DELTA.n.sub.2).gtoreq.0.04when the first core portion in the single-mode optical fiber has a mean relative refractive index difference of .DELTA.n.sub.1 with respect to the cladding portion and an outer diameter of a while the second core portion has a mean relative refractive index difference of .DELTA.n.sub.2 with respect to the cladding portion and an outer diameter of b.

Abstract: A furnace minimizes the lowering of the quality of optical fibers, especially those lowerings of the quality that stems from variations of the conditions inside of the furnace. These variations can occur when a preform is connected to an auxiliary quartz rod of differing diameters. Also, the furnace has an inlet sleeve which minimizes fluctuations in flow speed of the inert gases and the pressures inside the furnace.

Abstract: A method for manufacturing a glass preform from a metal sulfide chalcogenide glass to which a large amount of light emitting substances can be added includes steps of etching a surface made of the chalcogenide glass or oxychalcogenide glass of disc shape core and clad forming glass starting materials by an etchant including an acid and a compound reacting with a hydrogen chalcogenide, and forming the core forming glass starting material and the clad forming glass starting material into a united body serving as a glass preform. In a method for manufacturing a single-mode glass fiber using a preform method by drawing the glass preform whose outer round surface is made of a chalcogenide glass or oxychalcogenide glass, the outer round surface of the glass preform is etched using an etchant including an acid and a compound reacting with a hydrogen chalcogenide and then drawn into the glass fiber.

Abstract: There are provided an optical fiber rod overcladding apparatus and method, and an optical fiber drawing method. In the preform rod overcladding method, a preform rod is clamped in a top chuck and leveled, and a glass tube is mounted in a bottom chuck and leveled. The preform rod is coaxially inserted into a glass tube. Then, the glass tube is preheated by the furnace and heated by the burner until the glass tube reaches a softening point. The preform rod is completely sealed in the glass tube by sucking air in a clearance between the preform rod and the glass tube by application of a negative vacuum pressure. Thus, a preform is completed.

Abstract: A process for producing a preform for a chalcogenide glass fiber which comprises inserting a cladding tube having contained therein a chalcogenide glass rod for core into a quartz tube having at its bottom a nozzle having an aperture smaller than the outer diameter of the cladding tube, locally heating the bottom of the quartz tube and pulling the cladding tube having contained the glass rod for core and a process for producing a chalcogenide glass fiber by heating and drawing the preform thus obtained, by which processes the devitrification of glass and the generation of bubbles in the core glass or at the core glass-cladding glass interface can be prevented and the adhesion between the core glass and the cladding glass can be improved. In particular, when the glass material for core does not contain Ge, a chalcogenide glass fiber having such a core-cladding structure that the transmission loss of the glass fiber when infrared light pass through the fiber is small and the mechanical strength is high.

Abstract: Disclosed is a method of making an optical fiber preform having at least one annular region of depressed refractive index. A tube of silica doped with fluorine and/or boron is overclad with silica soot. A core rod is inserted into the overclad tube and the resultant assembly is heated while chlorine flows between the tube and the core rod to clean the adjacent surfaces. When the soot sinters, the tube collapses onto and fuses to the rod. The resultant tubular structure is formed into an optical fiber which exhibits low attenuation as a result of the low seed count at the interface between the inner core and the region that is doped with fluorine and/or boron.

Abstract: A vertically disposed apparatus used to make core-clad optical fibers inces an inner elongated cylinder removably closed at the top and provided at the bottom with an inner exit port of a smaller diameter than the inner cylinder and an outer cylinder, disposed around the inner cylinder, removably closed at the top and provided at the bottom with an outer exit port of a smaller diameter than the outer cylinder. The inner exit port is of a smaller diameter than the outer exit port and is disposed directly above the outer exit port. The apparatus also includes a heater for heating the inner and outer cylinders and acces to the inner and the outer cylinders for individually pressurizing inner and outer cylinders.

Abstract: A cladding-pumped fiber structure, suitable for use as a laser, provides for efficient clad-to-core energy transfer. The outside interface of the pump-clad is constructed from a rod-shaped preform by local melt-displacement using an open flame.

Abstract: A quartz glass tube, produced by mechanically processing a natural/synthetic quartz glass mother material, having 50-300 mm.phi. in outer diameter, from. 1 to 7 in outer to inner diameter ratio, 10 mm or more in thickness and 2% or less in thickness error; a large-scale quartz glass preform integrally combining the large-sized quartz glass tube with a core glass rod for an optical fiber using a rod-in-tube technique; and a method for manufacturing a large-scale quartz glass preform performing the mechanical processing with a high precision machine, i.e., integrating a core rod for an optical fiber under a rod in process with a quartz glass tube, a tube diameter of which is controlled by heating, hot drawing or hot drawing with pressure by using a tool-free drawing method.

Abstract: A method for fabricating a large-sized primary treated quartz glass tube by perforating a cylindrical quartz glass mother material by a hot carbon drill press-in-process followed by etching and washing. The large-sized primary treated quartz glass tube is converted to a large-sized quartz glass preform by combining it with a core glass rod for an optical fiber. Another embodiment is a method for fabricating a large-sized quartz glass tube by heating, hot drawing or hot drawing under pressure using a tool-free drawing method under control of an inside pressure of the large-sized primary treated quartz glass tube at a temperature ranging from 1600.degree. C. to 3000.degree. C. to satisfy a specific equation.

Abstract: A solid or hollow cylindrical heat-resistant substrate having a tapered shape is rotated about its axis, the degree of tapering being essentially constant along the entire length. The substrate has an outer diameter in the range of 20 mm to 500 mm and a length in the range of 500 mm to 5,000 mm. A mother material body made of porous quartz glass is formed on the outer surface of the substrate by chemical deposition, and vitrified by heating while holding it vertically with the larger outer-diameter side of the heat-resistant substrate positioned downward. Alternatively the heat-resistant substrate is extracted from the mother material body and a heat-resistant tapered body with a taper similar to that of the substrate is inserted into the hole left after extraction in the central region of the mother material body. The mother material body is vitrified starting at the lower end with the larger outer-diameter side positioned downwardly.

Abstract: A method of making 1.times.2 or 2.times.2 overclad couplers, switches and the like such that the process is more reproducible and loss characteristics are improved. Such couplers are typically made by inserting the stripped portions of two active optical fibers into a tube, heating the tube midregion to collapse it onto the fibers and stretching the central portion of the collapsed midregion to achieve the desired coupling characteristics. The improvement involves the insertion of one or two spacer fibers into the tube bore along with the active fibers to take up empty space that had been present in tube bore and to prevent an active fiber from sagging and crossing over the other fiber when the tube is heated during the tube collapse step.

Abstract: Core/clad glass optical fiber preforms free of bubbles and soot at the coclad interface are fabricated by inserting a glass core rod into a cladding glass tube sized so that space remains between them, sealing the top and bottom of the tube onto the core rod to form a sealed space between them which is relatively soot free and under a vacuum and then hot isostatically pressing the sealed composite to collapse the tube onto the rod and also collapse bubbles in the glass. Soot formation is avoided or minimized by purging the space with inert gas while the bottom of the tube is collapsed onto the rod and by sealing the top under a dynamic vacuum and at the lowest possible temperature to avoid soot formation without cracking the glass. The space is vacuum outgassed before the second seal is made. Chalcogenide fiber drawn from a preform made in this fashion exhibits very low transmission losses.

Abstract: Disclosed is an optical fiber capable of preventing an increase in an optical loss from occurring during fabrication and extraction of a single mode fiber preform and enhancement of an optical transmission efficiency, a method of producing the same comprising the steps of forming a first quartz robe having a first thermal conductivity, said first quartz tube being used as a clad; depositing a core layer and a clad layer inside the first quartz robe to form a preliminary perform by heating of the fist quartz robe; forming a second quartz tube having a second thermal conductivity lower than the first thermal conductivity; and depositing the second quartz tube to said preliminary preform by heating to produce the optical fiber preform. On embodiment, uses N overclad layers having thermal conductivites K.sub.x such that K.sub.0 >K.sub.1 >K.sub.2 . . . >K.sub.N and coefficients of viscosity .mu..sub.0 <.mu..sub.1 <.mu..sub.2 . . . <.mu..sub.N.

Abstract: A method of manufacturing a preform for drawing into an optical fibre comprises positioning a rod within a sleeving tube therefor to form an assembly in which there is an annular space between the rod and tube, and collapsing the tube onto the rod to form a solid cross-section preform. The collapsing step comprises sealingly closing the annular space at one end of the assembly and applying suction to the annular space from the other end of the assembly. The annular space at the one end is sealingly closed by locating the end of the tube at the one end on an annular rib of the rod and fusing the tube end to the rib.

Abstract: A method and apparatus are provided for forming a glass preform which can be directly drawn into a single or multi-mode optical fiber. Single or multi-mode fibers drawn from the preforms described herein have high quality core-clad interfaces since the core and cladding materials are not exposed to crystallization temperatures upon the addition of the core material to cladding material.

Abstract: A method and apparatus are provided for drawing a self-aligned core fiber free of surface contamination and inserting the core fiber into a cladding material to make an optical fiber preform. Single or multi-mode optical fibers having high quality core-clad interfaces can be directly drawn from the preforms described herein.

Abstract: The surface quality of halide, preferably fluoride, articles, e.g. articles used in the preparation of halide fibres is improved by cleaning the surface with an aqueous etchant and thereafter removing the etchant by washing the surface with methanol. The aqueous etchant is preferably a solution which contains hydrochloric acid and zirconium oxychloride.

Abstract: In accordance with the invention, a plurality of elongated refractory bodies are laminated together by placing the bodies in close adjacency, exposing the adjacent bodies to a plasma torch heat source, and moving the bodies longitudinal past the torch at a nonzero average rate which includes a reciprocating (e.g., oscillatory) component to longitudinally spread the zone of heating. Where the bodies are a rod to be laminated within a hollow tube, it is advantageous to reduce the air pressure between the rod and tube, thereby eliminating potential contaminants and, at the same time, biasing the tube to collapse against the rod. This method is particularly useful in laminating overcladding tubes to core rods to form optical fiber preforms.

Abstract: Sol-gel processing of a silica glass body is facilitated by rapid drying. The body, having been heated to a temperature of about 200.degree. C. in a hermetically sealed vessel, is vented while reducing temperature. Termination of drying coincides with reduction to atmospheric pressure.

Abstract: Heating a wet colloidal gel body in an autoclave above its 1-atmosphere boiling point, under rigorously defined conditions, avoids shrinkage during subsequent drying. As a consequence, drying rates may be increased, and handling care becomes less critical.

Abstract: A method and apparatus are provided for forming a glass preform which can be directly drawn into a single or multi-mode optical fiber. Single or multi-mode fibers drawn from the preforms described herein have high quality core-clad interfaces since the core and cladding materials are not exposed to crystallization temperatures upon the addition of the core material to cladding material.

Abstract: In one embodiment, the present invention includes a method of increasing the attachment bond strength between a first and second object comprising respective first and second materials. Each of the first and second materials has a respective first coefficient of thermal expansion at an assembly temperature, and a second coefficient of thermal expansion at an operational temperature. The method has various steps (FIG. 4). An attachment surface of the first material is configured to be nonplanar (FIG. 3a, 36, 37). The second material is brought to a contact point with the attachment surface of the first material (FIG. 3b, 46). The first and second materials are heated at the contact point to the assembly temperature whereby at least one of the materials is caused to flow in response to the heat.

Abstract: A method of making a preform for an optical fiber, in which method a plurality of layers of fluoride glass are deposited inside a support tube (10); said layers (14) are deposited by laser ablation in a controlled atmosphere using a target (12) having the composition of said glass, which target is moved back-and-forth parallel to the axis of said tube, the temperature of the enclosure (1) in which said ablation is performed being not greater than the vitreous transition temperature Tg of said glass.

Abstract: The present invention provides a method of manufacturing an optical fiber preform having the steps of disposing a rod member made of a silica-based material within a cavity of a mold, followed by loading a molding material within the mold cavity, and applying pressure to the mold from the outside to form a porous layer on the surface of the rod member and, thus, to obtain a porous preform, wherein at least one end portion of the rod member extends outside the mold cavity in the step of applying pressure to the mold. The particular method permits manufacturing a high quality porous preform free from splits or cracks, making it possible to obtain a high quality optical fiber preform free from residual bubbles.

Abstract: In a method of manufacturing a cylindrical part from glass, especially but not exclusively fluorinated glass, a vertical cylindrical cavity is lined with a porous material and its inside dimensions are a few tens of microns greater than those of the part. A cylindrical pedestal constituting a support for the part slides in the cavity. An initial seed mass constituted from the glass is provided on the pedestal. The seed mass is heated until it melts and a gas is injected permanently into the porous material in order to maintain between them and the molten seed mass a layer of gas a few tens of microns thick to prevent any contact. The molten seed mass is fed continuously from the top of the cavity with the powder constituents of the glass and the pedestal is lowered as the cylindrical part is formed from the seed mass.

Abstract: A method for producing an optical fibre which has been treated with titanium dioxide to improve its corrosion resistance includes stretching an assembly consisting of an outer sleeve having engaged therein a bar which is partially or entirely made of synthetic silica. When treating said fibre, the outside of the coupling sleeve is coated, prior to assembling the components, with a deposit of vitrified synthetic silica containing titanium dioxide.

Abstract: A low loss fiber optic coupler of the type wherein a plurality of single-mode optical fibers are fused together along a portion of the lengths thereof to form a coupling region. Each fiber includes a core and a cladding, the lowest refractive index of the fiber claddings being n.sub.2. Each of the output fibers of the coupler further includes a surface region of refractive index n.sub.4 that inhibits the coupling of light to lossy composite modes, n.sub.4 being lower than n.sub.2.