Abstract: A method for producing an optical multiple fiber unit wherein a multiplicity of optical fibers are fused together with each other and each optical fiber has a core made of pure silica glass and a cladding layer made of silica glass containing a dopant and disposed on the core, by bundling a multiplicity of preforms corresponding to the optical fibers and drawing the bundle at a high temperture using the optical fiber preforms, preforms having a three-layer construction wherein a support layer made of a silica glass having a drawable temperture of at least 1,800.degree. C. is further disposed on the cladding layer, and drawing the bundle of the preforms to give a multiple fiber wherein the support layer of each optical fiber has a thickness of 0.01 to 1 .mu.m, in order to produce a multiple fiber in which the cladding layer of each optical fiber has a sufficient thickness to fulfill the function as a cladding layer and which has an excellent image-transmitting capacity.

Abstract: A method of forming a fibre optic terminal assembly (17) comprising the steps of inserting fibres (8) into a duct (3) defined by a housing (1) comprising a sleeve portion (21) having an open end (10) and defining a tubular portion of the duct, the fibres being inserted such that the fibres are supported in a closely packed bundle throughout the tubular portion and project through the end of the sleeve portion, trimming the bundle to form an end face (11) thereof, and bonding the fibres to one another and to the housing thereby forming a terminal assembly. The fibres are bonded by applying heat locally to the end face to form a molten glass surface layer, allowing glass from the layer to flow between the fibres of the bundle and allowing the glass to cool such that the glass forms a matrix fusing the fibres to one another and to the housing.

Abstract: A method for fabricating a high efficiency optical coupler by matching the emerging light exit pupil from a coupler opening to the acceptance shape of a coupler optical fiber. An excimer laser forms the coupler opening in an optical fiber by removing cladding from the optical core surface. The coupler opening has an elliptical shape resulting in an emerging light exit cone and that exit cone matches an acceptance cone of a circular coupler optical fiber.

Abstract: A fiber optic coupler is formed by assembling a coupler preform having two concentric glass tubes having a gap between them. The shape and/or size of the inner tube relative to the shape and/or size of the outer tube is such that a plurality of output optical fibers can be equally spaced in the gap. An input optical fiber is disposed in an aperture in the inner tube. The input and output fibers extend through the midregion of the resultant coupler preform. The midregion is heated to collapse it about the fibers, and the central portion of the midregion is stretched to reduce the diameter over a predetermined length.

Abstract: Fusion-splicing polarization maintaining optical fibers includes the steps of: observing a polarization maintaining optical fiber containing stress applying members in a predetermined direction, using a core direct monitoring method to obtain a reference image; aligning the pair of polarization maintaining optical fibers to be fusion-spliced; automatically rotating the fibers while observing them with the core direct monitoring method until the images of the pair coincide with the reference image; and fusion splicing the pair together.

Abstract: The present invention is drawn to a method for forming a section in which a plurality of optical branch fibers are joined with each other. The branch fibers are connected with a single optical trunk fiber at the end faces thereof contacting each other. The configuration and area of the end face of the joined section of branch fibers are substantially identical to those of the end face of the trunk fiber. A die has a through-hole, for shaping the branch fibers, the sectional area and configuration of which are equal to those of the end face of the trunk fiber as taken perpendicular to the axis thereof. The branch fibers supplied to the heated die at a predetermined amount ratio are simultaneously drawn through the die. The ratio between amounts of respective branch fibers to be supplied to the die is set to correspond with a desired signal branching ratio of the optical coupler to be obtained.

Abstract: A fiber optic coupler is formed by providing a glass tube having a longitudinal aperture. Glass optical fibers, each having a core, cladding and coating are disposed within the longitudinal aperture, the fibers extending beyond each end of the tube. The coating is removed from that portion of the fibers in the midregion of the tube but remains on that portion of the fibers extending into the ends of the apertures. The aperture is formed by a plurality of flattened walls, the dimensions and orientations of which are such that the cross-section of the aperture in the central region of the tube is symmetrical with respect to a plane passing through the longitudinal axis of the tube. At any cross-section of the aperture that is adjacent the coated regions of the fibers, each fiber coating contacts two walls of the aperture. The fibers are held taut to effect a tension, and the midregion of the tube is heated, collapsed about the fibers, and drawn to reduce the diameter thereof over a predetermined length.

Abstract: In a method for the production of cylindrically symmetric bodies with given radial gradient of the material properties, for example of the refractive index, at least two rod-shaped molded bodies consisting of materials with different properties are joined in parallel and, following lowering of the viscosity of both materials, the bodies are twisted many times in a spiral around a longitudinal axis, such that a desired radial gradient of the material properties arises, where metallic, semiconducting, or insulating materials may be used, and the viscosity is varied through changing the temperature or adding or removing a solvent.

Abstract: An overclad fiber optic coupler is formed from a coupler preform including a glass tube having a longitudinal aperture. The aperture is formed of a plurality of similarly shaped side walls, each of which includes a longitudinally extending, inwardly projecting protrusions. The region between each two adjacent protrusions constitutes a corner region. Disposed within the aperture are at least a portion of each of a plurality of glass optical fibers, one fiber being situated in each corner region. The midregion of the tube is collapsed onto the fibers, the protrusions maintaining the fibers in their relative positions. At least a portion of the midregion is stretched to reduce the tube midregion diameter.

Abstract: A fiber optic coupler is formed by providing a glass tube having a longitudinal extending aperture. Protective coating is removed from a region of a first optical fiber intermediate the end. Protective coating is removed from an end region of at least one other optical fiber. The coated portion of the first fiber is threaded through the tube until the uncoated region is near the tube end. The uncoated region of the second fiber is placed adjacent that of the first fiber, and both uncoated regions are simultaneously fed into the tube aperture. The threading operation is continued until the uncoated regions extend through the midregion of the tube, the midregion is heated to collapse it about the fibers, and the central portion of the midregion is drawn to reduce the diameter along a predetermined length.

Abstract: Methods for bonding transparent materials to opaque materials. The materials to be bonded are placed in tightly abutting relation to one another, and an energetic laser pulse is directed through the transparent material until it melts a thin surface layer of the opaque material. The desired bond is formed when the melted layer solidifies. In alternative embodiments the transparent material is precoated with various mediator materials to facilitate the bonding process.

Abstract: An optical fiber splice and the method of forming it are described wherein a hollow cylindrical glass member is provided, the member having a bore along the longitudinal axis thereof. Fluid at a pressure in excess of ambient pressure is provided to the bore while the member is subjected to localized heating of the member to the softening point of the glass. In this manner, a bubble is formed within the member bore under the influence of said heating and pressure. For more uniform bubbles, the member may be rotated about its longitudinal axis while it is subjected to said fluid pressure and heating. The splice member is subsequently formed by severing the cylindrical member at the location of the bubbles. Optical fibers may be inserted into the ends of the splicing member and cemented in place.

Abstract: A method of fabricating a fused fibre optic coupler includes disposing two or more segments of optical fibre under longitudinal tension. The tensioned fibre segments are preheated to a temperature sufficient to soften the segments and thereby substantially relieve their tension by inelastic stretching of the segments. After the segments have cooled, the fibre segments are re-tensioned and then heated while in intimate side-by-side contact to a temperature sufficient to cause the fibre segments to fuse together.

Abstract: Two optical fibers are spliced together to form a single spliced optical fiber. The spliced region is uncontaminated by impurities, and has substantially no loss of optical transmission or mechanical strength as compared to the other regions of the fibers. Splicing is accomplished by removal of the buffer coating, if any, cleaving of the fibers to be spliced to form facing splicing surfaces, careful precleaning of the cleaved fibers in the region adjacent the splicing surfaces, aligning the fibers using optical transmission as the alignment criterion, fusing the fibers together by preheating the region to be spliced, fusing the region, postannealing the spliced region, carefully postcleaning the spliced region, and recoating the spliced region with a UV curable polymer buffer material, if desired. The heating of the fibers to accomplish the fusion is desirably accomplished by a laser such as a carbon dioxide laser.

Abstract: A method of forming an optical fiber joint between a pair of elongated optical fibers each of which has a longitudinal axis surrounded by a core and cladding having different refractive indices and forming a single-mode light-guiding region, the core and cladding of each fiber having non-circular transverse cross-sections defining two polarization-maintaining axes of birefringence transverse to the longitudinal axis of the fiber. Each of the fibers also has predetermined external flat reference surfaces for locating the core and cladding and the axes of birefringence within each fiber from the exterior geometry of the fiber.

Abstract: Disclosed is a method of fusion splicing single-mode optical fibers, in which an offset distance D, between the axes of the optical fibers subjected to fusion splicing, is measured when the axes of the cores of the optical fibers are aligned with one another. The arc discharge time, current and/or energy is determined according to the measured distance D.

Abstract: Disclosed is a method of manufacturing a preform for an asymmetric optical fiber which comprises the steps of (a) fixing plural transparent glass rods involving at least one core-mother rod functioning as the core in said optical fiber in parallel relationship, (b) depositing glass soot around an assembly of said plural parallel fixed glass rods, thereby providing a single porous cladding bearing the predetermined shape, and (c) vitrifying the porous cladding by thermal fusion, thereby providing the entirely integral transparent preform. The above method does not involve any process of perforating a drilled-pore which is needed inevitably in conventional method. Therefore, it is possible to obtain a long preform with high dimensional precision, and to fabricate the optical fiber with low transmission loss.

Abstract: A method of making an economical fiber coupler comprises providing a glass tube having first and second end portions and a midregion, and a longitudinal aperture extending therethrough. Two suitably prepared glass optical fibers, each having a core and cladding, are disposed within the longitudinal aperture, the fibers extending beyond each end thereof. The fibers are held taut to effect a tension therein, and they are glued to each end portion. The midregion of the member is heated, collapsed about the fibers, and drawn to reduce the diameter thereof.

Abstract: A fiber optic coupler is formed as follows. Glass optical fibers, each having a core, cladding and coating are disposed within the longitudinal aperture of a capillary tube, the fibers extending beyond each end thereof. The fibers are preferably held taut to effect a tension therein. The coating is removed from that portion of the fibers in the midregion of the tube by oxidation, depolymerization or the like. The coating remains on those portions of the fibers extending into the ends of the apertures to precisely orient the fibers within the tube. The midregion of the tube is heated, collapsed about the fibers, and drawn to reduce the diameter thereof.

Abstract: A fiber optic coupler is formed by providing a glass tube having a longitudinal aperture extending therethrough. Glass optical fibers, each having a core, cladding and coatng are disposed within the longitudinal aperture, the fibers extending beyond each end thereof. The coating is removed from that portion of the fibers in the midregion of the tube but remains on that portion of the fibers extending into the ends of the apertures. The aperture is formed by a plurality of flattened walls, the dimensions and orientations of which are such that the cross-section of the aperture in the central region of the tube is symmetrical with respect to a plane passing through the longitudinal axis of the tube. At any cross-section of the aperture that is adjacent the coated regions of the fibers, each fiber coating contacts two walls of the aperture.

Abstract: There is disclosed a method and apparatus for fixing a predetermined spacial orientation of exposed end portions of plurality of optical fibers included within a conductor unit; extending such exposed end portions between two terminal blocks for maintaining an axial tension therein; and scratching a surface of each of such end portions held in tension in a common transverse plane for causing each of such end portions to break and form a new end face. After such breaking, the spacial orientation of the remaining exposed end portions of the optical fibers is continued during the individual welding thereto of aligned end faces of a plurality of optical fibers of a second conductor unit.

Abstract: A pair of V-shaped slot blocks mounted movably on a base in both the X and Y directions and a microscope for observing the opposed state of optical fibers contained on the blocks, are provided in an apparatus for fusion splicing optical fibers. The microscope is mounted movably in the X and Y directions under a base, thereby observing the opposed states of the optical fibers from below.

Abstract: A method for producing reflectors in a continuous length of optical fiber is disclosed. The present process includes the steps of preparing the ends of two or more optical fibers, placing one or more of these fibers in a vacuum system and applying a metallic or dielectric coating to the fiber ends, and then fusing the prepared, coated ends of the fibers together until the reflectivity of the region reaches a desired value.

Abstract: Disclosed is a method of manufacturing a preform for an asymmetric optical fiber which comprises the steps of (a) fixing plural transparent glass rods involving at least one core-mother rod functioning as the core in said optical fiber in parallel relationship, (b) depositing glass soot around an assembly of said plural parallel fixed glass rods, thereby providing a single porous cladding bearing the predetermined shape, and (c) vitrifying the porous cladding by thermal fusion, thereby providing the entirely integral transparent preform. The above method does not involve any process of perforating a drilled-pore which is needed inevitably in conventional method. Therefore, it is possible to obtain a long preform with high dimensional precision, and to fabricate the optical fiber with low transmission loss.

Abstract: A method is disclosed in which the bare glass fibers are firmly soldered into a solder bath of the splicing device and, after being scored and broken, unsoldered again. To that end, the glass fibers are placed across the solder bath, the solder is heated, and the level of the molten solder is raised above the glass fibers by pressing a slide into the solder trough. The heat supply to the solder bath is subsequently cut off. After the solder has cooled, the glass fibers are firmly fixed therein. To release the fixed glass fibers, the solder is liquefied again. The device for carrying out the method consists essentially of a slotted guide bar, which serves to hold the glass fibers apart, and the solder bath. The latter is a copper block which is thermally insulated from the splicing device and has a projection at one end for attaching a soldering iron.

Abstract: A method for hermetically fastening a glass fiber within a tube, wherein the tube can be used with light wave guide components, the tube serving as a connecting part at the component. The method provides for a tube consisting of quartz, quartz glass or glass. The glass fiber is connected to the tube at a predetermined fastening location by means of heating the tube and collapsing the tube to hermetically connect the glass fiber to the tube through melting.

Abstract: A low loss fiber optic coupler is fabricated by forming a coupler preform having a plurality of spaced glass cores extending longitudinally through a matrix of glass having a refractive index lower than that of the cores. The preform is heated and stretched to form a glass rod which is then severed into a plurality of units. Heat is applied to the central region of each unit while the ends of the unit are pulled apart to elongate and taper inwardly the heated central region, whereby the cores of the unit are more closely spaced and are of smaller diameter at the central region than they are at the ends of the unit. The unit is then provided with a plurality of optical fibers, one of which extends from each of the cores at the endfaces of the unit. A preferred method of providing the optical fibers involves forming the coupler preform of a matrix glass that is easily dissolved in a solvent.

Abstract: A lightguide fiber (16), having predetermined losses, is fabricated from individual pieces (26) of fiber which are selected from an inventory thereof such that the median loss per unit length of pieces remains substantially the same after fiber fabrication. To fabricate the fiber, the inventory is first divided into a plurality of classes based on the following criteria: (1) whether each piece has a length above or below the average length of the pieces within the inventory. (2) whether each piece has a median loss per unit length above or below the median loss per unit length of the fiber to be fabricated, and (3) whether each piece has a variation in loss above or below a preselected value. Thereafter, the classes are successively examined, beginning with the first one, to determine whether any piece therein has transmission characteristics suitable for fabricating the fiber. If so, the piece is selected from the class.

Abstract: The method of this invention comprises first forming an assembly of a number N of cored glass fibers, separated by a number M of solid glass fibers. After a row of such alternated cored and solid glass fibers is assembled, a uniform pressure is applied to all sides of the assembly. All of the rectangular glass fibers are selected to have the same thermal properties, characterized especially by having the same softening temperature and the same coefficient of expansion. The entire assembly is inserted in an oven subject to a temperature sufficient to soften the glass and thus fuse the parts together. The assembly is cooled and the glass block is removed from the oven. The block can then be cut into thin nozzle wafers and finished to produce the desired jet nozzles. The method may use glass fibers made of two types of glass. The central portion of the fiber comprises a high-temperature glass, this portion surrounding the core.

Abstract: A low loss fiber optic coupler is fabricated by forming a coupler preform having a plurality of spaced glass cores extending longitudinally through a matrix of glass having a refractive index lower than that of the cores. The coupler preform is formed by inserting a plurality of coated optical fiber preform rods into an aperture extending axially through an elongated boule of relatively etchable matrix glass. The cladding portion of the rods, which is relatively etch-resistant, is coated with a layer of etchable glass. The coupler preform is heated and stretched to form a glass rod which is then severed into a plurality of units. Heat is applied to the central region of each unit, and the central region is elongated and tapered inwardly. When an end of the unit is immersed in acid, the matrix glass dissolves, thereby leaving the unit cores and surrounding etch-resistant cladding glass protruding from the newly formed endface of the unit.

Abstract: A method of preparing an optical device for alignment with a light beam emitter or receiver. The optical device is formed of a first glass that is resistant to dissolving in a given solvent. Extending through the device is an optical waveguide at least the cladding of which is soluble in the given solvent. At least one end of the device is immersed in the solvent to dissolve the end portion of the fiber and form a well. An optical fiber is inserted into the well where it is aligned with the fiber extending through the device.

Abstract: This invention is directed to a method for thermal pressing a glass-impregnated preform to create a composite body with a glass or glass-ceramic matrix. The method involves contacting the preform during pressing with members prepared from a material exhibiting significant impedance to heat flow in order to delay cooling of the preform during consolidation. The preferred preform consists of a stack of glass-impregnated plies having ceramic fibers and/or whiskers entrained therein.

Abstract: To enable sequential fusion splicing of the optical fibers of two lengths of optical fiber ribbon, the fusion splicer has, on each side of the fusion station, means for arranging the exposed end portions of the optical fibers of each ribbon, over a limited length between the position at which they are lightly clamped and the cut back end of the ribbon, to follow a curved path whose centers of curvature lie on a line extending transversely of the ribbon. Preferably, one of these means is an externally screw threaded rod which extends under and transversely of the optical fibers of one of the ribbons and in the grooves of which the optical fibers are arranged to lie. By unscrewing the rod, each lightly clamped optical fiber in turn drops from the rod and straightens so that its end to be fusion spliced protrudes beyond the ends of the other optical fibers of the ribbon. Fusion splicing of the pair of aligned optical fibers is then effected.

Abstract: A method of and an apparatus for coupling ends of first and second multicore coated optical fibers each having multiple optical fibers integrally covered with a coating. The method includes a clamping step of setting the first and second multicore coated optical fibers in first and second clamp members, respectively, a cutting step of cutting off exposed fiber ends of the first and second multicore coated optical fibers and a coupling step of coupling cut end faces of the optical fibers of the first and second multicore coated optical fibers such that the cutting step and the coupling step are performed without detaching the first and second multicore coated optical fibers from the first and second clamp members, respectively.

Abstract: In the interest of producing high-strength splice connections between silica-based glass fibers a method of using a tri-particle flow of gases for flame fusion is disclosed. An outer relatively high-velocity flow of oxygen surrounds an intermediate, lower-velocity flow of chlorine or oxygen which in turn surrounds a central flow of H.sub.2, D.sub.2, NH.sub.3, or ND.sub.3.Particularly high strengths are achieved when a central flow of hydrogen or deuterium and an intermediate flow of chlorine are used in such a fashion as to heat fiber ends to be spliced to temperatures of 500 degrees C. and beyond only after these ends have been enveloped by chlorine.

Abstract: A method of manufacturing a passive fiber optic component, in which two or more fibers are each bared at one end by removal of the outer coating of the fiber the bare portions of the fibers are etched to produce a cylindrical end portion which adjoins a conical portion. Subsequently, the fibers (1) are arranged with their etched portions in a capillary tube which is sealed at one end. The tube is then evacuated and is fused with the etched portions of the fibers to form a solid rod with a rotationally symmetric distribution of the end portions of the fibers. The fibers are etched to such a diameter that after fusion of the fibers with the tube, the fused fibers ends have a circular cross-section substantially equal to the cross-section of a single fiber core. An end face is formed on the rod by cleaving or by grinding, and by polishing to obtain a fused fiber head.

Abstract: In the interest of reducing the effect on tensile strength of flame processing of a silica-based optical fiber waveguide, such processing is by a method in which a significant flow of oxygen surrounds a flame produced by combustion of hydrogen, deuterium, ammonia, or deuterated ammonia. Flame processing may be for purposes such as, e.g., fiber drawing, fiber fusing for the sake of lateral coupling, refractive index modification by the diffusion of dopants, and fiber splicing in the manufacture of long lengths of fiber. Even though there is no use of chlorine, at least 80 percent of spliced fibers have a tensile strength greater than or equal to 500 kpsi (3.45 GPa) as is desirable in optical fiber cable manufacture.

Abstract: A method of achieving long-term stability in the transmission properties of high purity low-hydroxyl vitreous silica optical waveguide fibers having preexisting peroxy linkages disposed therein in which the peroxy linkages are exposed to deuterium molecules and the reaction between the deuterium molecules and the peroxy linkages to form deuteroxyl group is substantially enhanced by simultaneously or sequentially exposing the permeated fibers to a light source having an intensity of at least 10 Lambert Units and a wave length of from the short wave length absorption edge of vitreous silica up to about 650 nanometers until the absorption at 1.7 micrometers reaches saturation.

Abstract: There are disclosed an optical fiber junction device and a method of making the same. The method comprises the steps of providing a central inner pipe or rod of glass, arranging a plurality of optical fibers around the inner pipe or rod, and externally heating the optical fibers and the central inner pipe to form a thermally fused assembly having cores of a sectorial cross section. The inner pipe may include a tapered portion having a reduced diameter. The optical fibers may comprise optical fiber junction units each composed of a plurality of optical fibers.

Abstract: A method of making an optical fiber, comprising the steps of forming an optical preform having a core and a cladding with different refractive indices, the core being offset from the geometric center of the preform and having a non-circular cross-section defining two transverse orthogonal axes, the core having a longer transverse dimension along one of the orthogonal axes than along the other of the axes for guiding two fundamental modes, which, in combination with the different refractive indices, permits the de-coupling of waves polarized along the axes, the outer surface of the preform having a non-circular cross-section forming an indexing surface with a predetermined geometric relationship to the core and the orthogonal transverse axes so that the location of the core and the orientation of the axes can be ascertained from the geometry of the outer surface, and drawing an optical fiber from the preform with the drawing rate and the temperature of the preform being controlled to produce a fiber with a cro

Abstract: A chalcogenide glass rod and/or a fluoride glass rod are covered with a thermally shrinkable synthetic resin tube, the resulting assembly being heated under vacuum to produce a preform, and a thermally shrinkable synthetic resin tube with a plurality of said preforms formed in a bundle and inserted thereinto is drawn again under heating.

Abstract: A method of forming an optical shield for a laser catheter is disclosed in which a rod of light transmissive material is optically polished and inserted into a tube of similar material and fused and the distal end of the rod is cut and the assembly is optically polished at the distal end.

Abstract: A method for producing a bare fiber taper at a metallized fiber is disclosed and comprises the steps of softening and drawing in an arc of the fiber metallized by sputtering or vapor deposition. The softened metallized fiber thereby constricts and the metallized fiber becomes free of the metallization and, thus, bare over its entire circumference in the arising constriction as a consequence of the influence of the arc. The bare constriction produced in such fashion is parted and a tapering, bare end section thereby arising at one of the two metallized fiber halves produced by the parting can be employed as the bare fiber taper. A fiber taper with lens can be produced by fusing a lens to the bare end section.

Abstract: High-strength, low-loss splices of optical fiber can be produced by fusion splicing the fiber with a D.sub.2 -O.sub.2 flame. According to the invention, the deuterium concentration in the gas mixture used to produce the flame is at least 10% by volume of the reducing gas present in the mixture. Preferably, substantially all of the reducing gas in the mixture is deuterium, with oxygen the oxidizing gas species.

Abstract: A method of producing fiber reinforced glass composites of complex shapes (e.g. having curved portions such as cylindrical) is disclosed. A continuous length of fiber, such as silicon carbide, is passed through a slurry of glass powder and a carrier liquid containing a polymeric binder to impregnate the fiber. The impregnated fiber is next dried and woven into a predetermined structural shape. Plies of the woven fiber cut to near net shape may also be stacked into the desired shape. The thus laid fibers are hot pressed into a fiber reinforced glass matrix composite article having glass matrix distributed substantially uniformly therethrough and multiaxial strength in at least three mutually exclusive perpendicular directions.

Abstract: A method for fabricating an optical attenuator includes the following steps. Measuring the magnitude of optical loss imposed on an optical signal transmitted through first and second abutted optical fibers. Aligning the abutted ends of the first and second optical fibers for minimum distributed optical signal loss through both optical fibers, as measured at the far end of the second optical fiber. Heating the abutted ends of the first and second optical fibers into a plastic state. Physically distorting the optical fiber ends until the measured optical signal loss increases by a desired additional lumped optical loss value. Cooling the abutted ends of the first and second optical fibers to form a fusion splice imposing the desired additional lumped optical loss value between the ends of the first and second optical fibers.

Abstract: An advantageous method for fabricating an optical attenuator between the ends of two optical fibers uses the following steps. The axes of the cores of optical fiber ends are misaligned by an offset distance and then one of them is moved along its center axis until the ends of the fibers abut one another. Abutted ends of the optical fibers are melted. While the fiber ends are molten, surface tension aligns the axes of the cores of the optical fibers. Finally the abutted ends region of the optical fibers is cooled into a lumped optical attenuator.

Abstract: A process for producing an image fiber comprising drawing an image fiber preform consisting of a bundle of a plurality of optical fibers each of which is drawn from an optical fiber preform and consists of a core and a cladding, in which at least one of the optical fiber preform, the optical fiber, the image fiber preform and the image fiber is hydrogenated at a temperature higher than a room temperature, the image fiber produced having improved attenuation which is less increased when it is irradiated, particularly with gamma-ray.

Abstract: A method for forming an optical fiber from a single characteristic glass includes arraying hollow starter tubes about a central axis with each starter tube contacting its adjoining tubes along respective lines of contact to define a longitudinally extending opening about the central axis. The arrayed starter tubes are heated to cause them to fuse together along their lines of contact, and the fused starter tubes are inserted into a jacketing tube, preferably having the same physical and optical properties as the starter tubes. A pressure differential is established between the interior of the starter tubes and the tube-defined longitudinally extending opening. The tube assembly is heated to allow the established pressure differential to cause portions of the starter tubes to reform by moving toward and to the central axis to create a solid, void-free core and supporting webs. Other portions of the starter tubes expand toward and fuse to the interior surface of the jacketing tube.

Abstract: In a woven ceramic heat exchanger using the basic tube-in-shell design, each heat exchanger consisting of tube sheets and tube, is woven separately. Individual heat exchangers are assembled in cross-flow configuration. Each heat exchanger is woven from high temperature ceramic fiber, the warp is continuous from tube to tube sheet providing a smooth transition and unitized construction.