Abstract: The present invention relates to a fiber having a core of crystal fiber doped with chromium and a glass cladding. The fiber has a gain bandwidth of more than 300 nm including 1.3 mm to 1.6 mm in optical communication, and can be used as light source, optical amplifier and tunable laser when being applied for optical fiber communication. The present invention also relates to a method of making the fiber. First, a chromium doped crystal fiber is grown by laser-heated pedestal growth (LHPG). Then, the crystal fiber is cladded with a glass cladding by codrawing laser-heated pedestal growth (CDLHPG). Because it is a high temperature manufacture process, the cladding manufactured by this method is denser than that by evaporation technique, and can endure relative high damage threshold power for the pumping light.

Abstract: An optical fiber end processing method includes the steps of: an optical fiber fixing step of fixing two parts of the optical fiber; a first heating step of heating a tip end side part of the optical fiber between two fixed parts fixed in the optical fiber fixing step, and melting the optical fiber of the tip end side heating part; a second heating step of heating a part on a base end side of the optical fiber between the fixed parts away from the tip end side heating part in a state that two parts of the optical fiber are fixed, and making the holes of the optical fiber disappear; and a removing step of removing the tip end side heating part after the second heating step.

Abstract: The method for fabricating an optical fiber comprises the steps of inserting a primary optical fiber preform (11) having a first primary axis (x1) and an outer surface (111) into an overcladding tube (12) having a second primary axis (x2) and an inner surface (120), so that said outer surface and inner surface define an interior space (15); holding the primary preform (11) in a centrally inserted position within the overcladding tube (12) with said first and second primary axes (x1, x2) in substantial alignment with each other; supplying overcladding grain (13) into the interior space (15) that is limited at the lower end of the overcladding tube (12) by means of a closure (125); generating a condition of reduced pressure within the interior space (15) that is limited at the upper end of the overcladding tube (12) by means of an adjoiner (3), which holds the primary optical fiber preform (11) and the overcladding tube (12) in position; and heating the unprocessed secondary preform (1), that consists of the pr

Abstract: A method and structure for terminating an optical fiber are disclosed that provide an optical fiber termination structure with a small volume and very low return loss, even when the termination is in close proximity to reflective surfaces. In one example embodiment, the optical fiber termination reduces reflections into the one or more cores to a return loss of ?70 dB or less regardless of the presence of surfaces proximate the optical fiber termination. At the same time, a length of the optical fiber termination is less than 5 mm and a largest transverse dimension of the optical fiber termination is less than 325 um. The optical fiber termination is useful in fiber sensing applications in general and is particularly effective for terminating a multi-core fiber used in a distributed shape sensing application.

Abstract: A method of manufacturing an optical fiber preform includes preparing from a first deposition tube a first rod that includes a central core and preparing from a second deposition tube a second rod that includes a buried trench. The method further includes fitting the second rod as a sleeve over the first rod. This disclosed method facilitates the manufacture of large-capacity fiber preforms using deposition benches having small and/or medium deposition capacity.

Abstract: The method for producing and processing a preform comprises a preliminary process phase, in which silica grain is supplied into the interior space of a silica tube having an open upper end and a closed lower end, in order to obtain an unprocessed preform, and includes a final process phase, in which the interior space of the silica tube is closed, a condition of reduced pressure is generated, the unprocessed preform is heated with a final process temperature in order to fuse the silica tube and the silica grain. According to the invention the silica grain entering the interior space is thermally treated during the preliminary process phase with an intermediate process temperature that lies under the melting point of the silica grain.

Abstract: Cylindrical optical components of quartz glass are known, which have an inner zone made of an inner zone glass, which extends in the direction of the longitudinal axis and is surrounded by a jacket zone made of a jacket zone glass, the average pt wall thickness thereof varying at least over a part of its length in the direction of the longitudinal axis of the component. The aim of the invention is to provide a method that allows a simple and cost-effective production of such an optical component from quartz glass.

Abstract: The method for fabricating an optical fiber comprises the steps of inserting a primary optical fiber preform (11) having a first primary axis (x1) and an outer surface (111) into an overcladding tube (12) having a second primary axis (x2) and an inner surface (120), so that said outer surface and inner surface define an interior space (15); holding the primary preform (11) in a centrally inserted position within the overcladding tube (12) with said first and second primary axes (x1, x2) in substantial alignment with each other; supplying overcladding grain (13) into the interior space (15) that is limited at the lower end of the overcladding tube (12) by means of a closure (125); generating a condition of reduced pressure within the interior space (15) that is limited at the upper end of the overcladding tube (12) by means of an adjoiner (3), which holds the primary optical fiber preform (11) and the overcladding tube (12) in position; and heating the unprocessed secondary preform (1), that consists of the pr

Abstract: The invention relates to a method for manufacturing a final optical fiber preform by overcladding, said method comprising the steps of providing a primary preform; positioning said primary preform within at least one tube, wherein the at least one tube partly covers the primary preform to create a zone to be overcladded, being an overclad zone, which overclad zone is located on the primary preform outside the at least one tube; injecting a gas into the annular space between the primary preform and the at least one tube under overpressure relative to the pressure outside the at least one tube; overcladding the primary preform in the overclad zone with an overcladding material using an overcladding device. The invention also relates to an apparatus for carrying out the method. The invention allows overcladding a primary preform at low cost while maximally limiting the incorporation of impurities into the silica overclad.

Abstract: This method for drawing a quartz glass optical component shortens the pulling process and minimizes loss of material. An end face of a quartz glass hollow cylinder forms a tapered end portion to an attachment piece of quartz glass having a bore. The inner bore of the hollow cylinder and the bore of the attachment piece are at least temporarily interconnected fluidically as a passage bore. A cleaning fluid is passed through the inner bore of the hollow cylinder and the passage bore. A core rod of quartz glass, which rests on a contact surface of the attachment piece, is inserted into the inner bore of the hollow cylinder, and the hollow cylinder is continuously supplied to a heating zone, heated therein so as to form a drawing bulb, and the component is continuously drawn therefrom.

Abstract: A double-clad optical fiber fabrication method including the steps of: preparing a crystal fiber, inserting the crystal fiber into a silica capillary, attaching a sapphire tube to the periphery of the silica capillary, and applying a laser beam to the sapphire tube to increase the temperature of the sapphire tube and to further fuse the silica capillary with thermal radiation to have the fused silica capillary be wrapped about the crystal fiber, thereby forming the desired double-clad optical fiber.

Abstract: An optical fiber, which has a zero-material dispersion wavelength equal to or greater than 2 ?m, and a high nonlinear susceptibility ?3 equal to or greater than 1×10?12 esu, and uses tellurite glass having sufficient thermal stability for processing into a low loss fiber, employs a PCF structure or HF structure having strong confinement into a core region. This enables light to propagate at a low loss. The size and geometry of air holes formed in the core region, and the spacing between adjacent air holes make it possible to control the zero dispersion wavelength within an optical telecommunication window (1.2-1.7 ?m), and to achieve large nonlinearity with a nonlinear coefficient ? equal to or greater than 500 W?1 km?1.

Abstract: The specification describes methods for the manufacture of very large optical fiber preforms wherein the core material is produced by MCVD. Previous limitations on preform size inherent in having the MCVD starting tube as part of the preform process are eliminated by removing the MCVD starting tube material from the collapsed MCVD rod by etching or mechanical grinding. Doped overcladding tubes are used to provide the outer segments of the refractive index profile thus making most effective use of the MCVD produced glass and allowing the production of significantly larger MCVD preforms than previously possible.

Abstract: Methods of forming an overclad portion of an optical fiber are described which include positioning a core cane member in an overclad tube to form a rod and tube assembly. Thereafter, glass soot pellets are positioned in the rod and tube assembly between the core cane member and an interior sidewall of the overclad tube. The rod and tube assembly is then redrawn under conditions effective to form the overclad tube and the glass soot pellets into a continuous, void-free glass layer surrounding the core cane member at a sintering time tsinter of at least 1800 seconds thereby forming an overclad portion of an optical fiber.

Abstract: In a technique for fabricating a birefringent optical fiber, a preform rod is fabricated having a longitudinal axis, an outer peripheral surface, and a selected refractive index variation. At least one longitudinal groove is cut into the preform rod through its outer peripheral surface, wherein the at least one longitudinal groove has a cross sectional area equal to that of a respective birefringence-inducing stress element to be loaded into the groove, such that when the stress element is loaded into the groove, a portion of the stress element protrudes outside of the circumference of the preform. A respective birefringence-inducing stress element is loaded into the at least one longitudinal groove. A preform assembly is created by positioning the loaded preform rod within an overcladding tube. The preform assembly is drawn into optical fiber.

Abstract: Optical fiber preforms can comprise a glass preform structure with an inner cavity. A powder can be placed within the inner cavity having an average primary particle size of less than about one micron. The powder can be in the form of an unagglomerated particles or a powder coating with a degree of agglomeration or hard fusing ranging from none to significant amounts as long as the primary particles are visible in a micrograph. Powders can be placed within a preform structure by forming a slurry with a dispersion of submicron/nanoscale particles within a cavity within the preform. In other embodiments, a powder coating is formed within a preform structure by depositing the powder coating directly from a reaction product stream. The formation of the powder coating can be formed within the reaction chamber or outside of the reaction chamber by flowing the product particle stream through a conduit leading to the preform structure. In additional embodiments, a powder coating is placed on an insert, e.g.

Abstract: The present invention is generally directed to a device comprising multiple specialty glass optical fibers that combines several different mid-infrared optical signals from multiple optical fibers into one signal in a single optical fiber. In addition, the present invention provides for a method of making the device.

Abstract: An optical fiber preform manufacturing method includes: supporting a drilling jig in a radial direction of a preform that is cylinder-shaped; moving the drilling jig in a longitudinal direction of the preform; and forming a plurality of slits each extending in the longitudinal direction and each directed from an outer side of the preform toward a center the preform, and a plurality of holes each extending in the longitudinal direction and each connecting with an end of one of the plurality of slits in a depth direction of the one of the plurality of slits.

Abstract: The production of an optical component from quartz glass by elongation of a coaxial arrangement of a core rod and a hollow cylinder is known. The arrangement is thus introduced into a heating zone, such that the lower end begins to partly soften and the component drawn from the softened part. According to the invention, a pseudo-continuous method for the formation of the restriction in the inner passage of the hollow cylinder on which the core rod is supported, is disclosed, whereby an upper hollow cylinder is fused end on with a lower hollow cylinder to form an axial composite cylinder, a core rod is introduced into the lower hollow cylinder and the axial cylinder composite partly softened and elongated to form the optical component.

Abstract: A method for manufacturing a photonic crystal fiber including arranging a spacer formed of two or more spacer parts in a support tube such that the inner wall surface of the support tube has a substantially regular polygonal cross-sectional shape which allows closest packing of a core rod and a plurality of capillaries or the capillaries only; and forming a preform by packing in a support tube the core rod for forming a solid core and the capillaries for forming a cladding, or by providing a core space for forming a hollow core in a support tube and packing in the support tube a plurality of capillaries for forming the cladding; and drawing the preform into a fiber under heating.

Abstract: An optical fiber preform is fabricated by inserting a number of core body pieces end-to-end inside a glass cylinder, wherein the pieces may have a cladding-to-core diameter (D/d) ratio within the range of one to four. The cylinder with the inserted core body pieces is mounted vertically on a furnace and heated so that the cylinder becomes elongated and its outside diameter collapses to form a core rod from which core rod sections with D/d ratios greater than five, can be cut. A soot overcladding is deposited on the circumference of a core rod section until the diameter of the deposited soot builds to a determined value. The core rod section with the deposited soot overcladding is consolidated to obtain a finished optical fiber preform. The preform preferably has a D/d ratio of about 15 or more, and an optical fiber may be drawn directly from the preform.

Abstract: A method of producing a large mode area optical preform includes selecting a preexisting rod and at least one preexisting outer tube. The rod and tube are selected so that a difference between respective indices of refraction is uniform and lies within the desired range, and a ratio between respective rod and tube diameters is within the desired range after the rod is inserted into the tube and both are thermally treated. The predetermined ranges are selected to provide mass production of a large mode area fiber with the desired physical and geometrical characteristics.

Abstract: A method for manufacturing a preform having a core and a multilayer clad, includes covering a circumference of a rod including at least the core and an inner clad layer with a first tube including at least a high viscosity clad layer, and unifying the rod and the first tube by heating and contracting the first tube.

Abstract: A multicore optical fibre includes a microstructured cladding material formed from a plurality of cladding elements arranged in an array and each cladding element comprising at least two different materials each having different refractive indices, and a plurality of core elements formed within interstitial regions between adjacent cladding elements. A fibre so formed may have a large number of cores per unit cross-sectional area as compared with prior art fibres, and thus allows the fibre to have relatively short distances between adjacent cores for a given required inter-core isolation. A fibre so formed has utility in many areas requiring high core density, such as inter-chip optical communication, or optical communication between circuit boards.

Abstract: Core rods or other glass components associated with optical fiber preforms are cleaned by loading them into a number of first sleeves, and partially obstructing entrance and exit ends of the sleeves to retain the components. The sleeves are contained inside a second sleeve so that the entrance ends of the first sleeves face an entrance end of the second sleeve. A fluid delivery system supplies cleaning fluids to the entrance end of the second sleeve, so that the fluids enter the first sleeves and contact exposed surfaces of the loaded components. The fluids leave the exit ends of the first sleeves and purge from an exit end of the second sleeve. Separators may be placed between the components in the first sleeves to enhance cleaning action and to cushion adjacent end faces of the components. Cleaned components may be unloaded from the first sleeves without risk of contamination.

Abstract: A fabrication method of an optical fiber using as a core material tellurite glass. The method includes a first process of molding a tellurite glass melt into a mold, the mold having a plurality of convex portions defining an inner wall, which portions run parallel to each other in a longitudinal direction in order to make a polygon columnar glass preform, and a second process of inserting the glass preform into a cylindrical jacket tube made of tellurite glass and carrying out fiber-drawing under pressure so as to maintain or enlarge air holes which are gaps generated between the glass preform and the jacket tube.

Abstract: The present invention provides a method for manufacturing an optical fiber comprising the steps of forming a glass body containing a core, preparing a glass tube which will form a cladding portion, inserting the glass body into the glass tube, and collapsing the glass tube with the glass body by heating, wherein the method comprises a step of processing the glass tube such that it has at least one end tapered to which a pull is to be applied. The method may further comprise the steps of cleaning the outer surface of the glass tube, choosing the outer diameter of the glass body and the inner diameter of the glass tube such that the difference between the two diameters is not lower than 1.0 mm but not higher than 10.

Abstract: A fiber optic connector assembly and method for venting gas inside in a fiber optic connector sub-assembly. The fiber optic connector assembly includes a connector sub-assembly including a ferrule and a ferrule holder having a passage extending therethrough. A stiffener tube having a tube body disposed about a portion of at least one optical fiber supports insertion of the optical fiber into the ferrule holder passage. The stiffener tube contains at least one opening in its tube body configured to vent gas trapped inside the stiffener tube during assembly. In this manner, the trapped gas does not form a gas pocket in the bonding agent, which could compromise bonding among the optical fiber, stiffener tube, and connector sub-assembly.

Abstract: A method for manufacturing an optical fiber includes the steps of covering an outer periphery of a first glass (11) having a first softening temperature and a non-axisymmetric structure by a second glass (12, 13) having a second softening temperature which is lower than the first softening temperature, heating the first and second glasses (11, 12, 13) for fusion together to thereby obtain an optical fiber preform; and drawing the preform to the optical fiber.

Abstract: In one embodiment, an apparatus includes an optical fiber made of a silica-based material. A proximal end portion of the optical fiber has an outer-layer portion. The proximal end portion can be included in at least a portion of a launch connector configured to receive electromagnetic radiation. The apparatus also includes a component that has a bore therethrough and can be made of a doped silica material. The bore can have an inner-layer portion heat-fused to the outer-layer portion of the optical fiber. The component can also have an index of refraction lower than an index of refraction associated with the outer-layer portion of the optical fiber.

Abstract: A method for manufacturing a polarization-maintaining optical fiber is provided. The method includes (a) making a fiber preform by providing in an over-cladding tube: a core rod having an inner core and a cladding surrounding the inner core; at least one stress-applying part (SAP) disposed adjacent to the core rod along an outer periphery of the cladding thereof and having a coefficient of thermal expansion different from that of the cladding; inner filler rods arranged along the outer periphery of the core rod at positions where the SAP is not disposed and having a coefficient of thermal expansion different from that of the SAP; and a plurality of outer filler rods arranged adjacent the over-cladding tube between the over-cladding tube and inner filler rods, SAP and core rod, and consisting of a same material as the over-cladding tube; and (b) drawing the fiber preform to obtain the optical fiber.

Abstract: One or more silica optical fibers (22), especially for use in downhole distributed temperature sensing and similar applications, are deployed in a corrosion resistant metal alloy control line (20) which is electrically insulated with, for example, EPDM. The insulation layer may be covered by a fluid resistant sealing layer (26), which may in turn be covered by a mechanical armor layer 28. The resultant composite optical fiber cable exhibits improved resistance to degradation of optical performance at elevated temperatures over about 100 deg. C.

Abstract: Apparatus and methods provide for cables with secured terminations. For some embodiments, a cable includes an inner tube surrounding an optical fiber, an aluminum tube surrounding the inner tube, and armor tubing surrounding the aluminum tube. The aluminum tube resists collapse of the inner tube at bends in the cable, inhibits or prevents hydrogen from reaching the fiber, and facilitates termination of the cable. For example, terminating the cable may include crimping the armor tubing to deform the aluminum tube into gripping engagement with an outside of the inner tube and an inside of the armor tubing. In some embodiments, a retention assembly secures the fiber relative to the inner tube and includes a retention tube secured to the inner tube and a packing sleeve squeezed into gripping engagement with the fiber by radial inward deformation of the retention tube where the packing sleeve is disposed in the retention tube.

Abstract: The present disclosure relates to a telecommunications cable having a jacket including a feature for allowing post-extrusion insertion of an optical fiber or other signal-transmitting member. The present disclosure also relates to a method for making a telecommunications cable having a jacket including a feature for allowing post-extrusion insertion of an optical fiber or other signal-transmitting member.

Abstract: A core rod is inserted into a cladding pipe, moisture in a space between the core rod and the cladding pipe is removed, and an optical fiber is drawn while the space is connected to a dry-gas atmosphere and/or being decompressed and while the core rod and the cladding pipe are being unified with each other. Alternatively, the core rod is inserted into the cladding pipe, and an optical fiber is drawn from one end while moisture on the surface of the core rod and the internal surface of the cladding pipe is being removed. Accordingly, a high quality optical fiber is manufactured with good productivity.

Abstract: Disclosed is an optical fiber cable that includes optical fibers and a deformable coupling element enclosed within a buffer tube. The coupling element is formed from a deformable yet substantially incompressible material and features a number of raised members projecting toward the optical fibers. The design of the coupling element layer permits coupling of the optical fibers to the buffer tube without the use of a compressive cushioning layer. This arrangement distributes the compressive force applied to discrete points along the outer perimeter of the optical fiber element.

Abstract: Disclosed is an optical fiber cable that includes optical fibers and a deformable coupling element enclosed within a buffer tube. The coupling element is formed from a deformable yet substantially incompressible material that is capable of releasably and intermittently coupling the optical fibers to the buffer tube in various orientations. The design of the coupling element layer permits coupling of the optical fibers to the buffer tube without the use of a compressive cushioning layer and yet permits localized movement the optical fibers relative to the buffer tube to account for disparate thermal expansion and to accommodate optical fiber placement.

Abstract: Low-loss large diameter optical waveguide attachment devices (i.e., pigtails) and methods and systems of making the same are provided. The optical waveguide attachment devices may include an optical fiber (or other type waveguide) embedded in a larger diameter carrier tube. According to some embodiments, multiple laser beams (from one or more laser) may be utilized to uniformly heat the circumference of the carrier tube. According to some embodiments a maria may be formed in one end of the capillary tube to facilitate optical waveguide insertion and/or provide strain relief.

Abstract: A core rod is inserted into a cladding pipe, moisture in a space between the core rod and the cladding pipe is removed, and an optical fiber is drawn while the space is connected to a dry-gas atmosphere and/or being decompressed and while the core rod and the cladding pipe are being unified with each other. Alternatively, the core rod is inserted into the cladding pipe, and an optical fiber is drawn from one end while moisture on the surface of the core rod and the internal surface of the cladding pipe is being removed. Accordingly, a high quality optical fiber is manufactured with good productivity.

Abstract: Embodiments of the invention include an optical fiber preform assembly and a method for making optical fiber using the preform assembly. The assembly includes a preform core rod, at least one overclad tube formed around the preform core rod, a handle attached to one end of the overclad tube, and a refractory material positioned in the overclad tube between the preform core rod and the handle. The refractory material reduces if not prevents movement of the preform core rod into the handle during the fiber draw process. Preferably, the refractory material is made of, e.g., magnesium oxide and/or aluminum oxide, and has a melting point, e.g., greater than approximately 2000 degrees Celsius. Embodiments of the invention also include a method for making optical fiber using this preform assembly.

Abstract: A method for forming a multicore fiber laser array includes inserting a plurality of rare-earth doped rods into a corresponding plurality of hollow capillaries, and arranging the resulting plurality of filled capillaries into a preform pattern. The plurality of filled capillaries are collapsed into an initial preform structure, wherein a portion of the material of the capillaries forms an initial inner cladding. The initial preform structure is inserted into a cylinder, wherein the cylinder and the initial preform structure are fused so as to form a final preform structure with a final inner cladding having an increased thickness with respect to the initial inner cladding. At least one flat surface is formed along the length of the final preform structure, and a fiber is simultaneously drawn from the final preform structure and a layer of outer cladding material.

Abstract: On the basis of a known process for the production of a preform for an optical fiber for optical data transmission technology, the productivity of the process for the production of complex refractive index profiles is to be improved by providing a quartz glass substrate tube which exhibits different doping in radial direction, introducing a core glass made of synthetic quartz glass into the substrate tube and covering the substrate tube with a jacket tube. A substrate tube suitable therefor is also being provided which tube requires less core glass material for the production of the preform, whether during the internal deposition or for the core glass rod in the rod-in-tube technique.

Abstract: The present invention provides a method for making a multicore large diameter optical waveguide having a cross-section of at least about 0.3 millimeters, two or more inner cores, a cladding surrounding the two or more inner cores, and one or more side holes for reducing the bulk modulus of compressibility and maintaining the anti-buckling strength of the large diameter optical waveguide. The method features the steps of: assembling a preform for drawing a multicore large diameter optical waveguide having a cross-section of at least about 0.3 millimeters, by providing an outer tube having a cross-section of at least about 0.3 millimeters and arranging two or more preform elements in relation to the outer tube; heating the preform; and drawing the large diameter optical waveguide from the heated preform. In one embodiment, the method also includes the step of arranging at least one inner tube inside the outer tube.

Abstract: An optical fiber preform comprises a central core portion having a maximal value Nc of refractive index in the center, and outside the central core portion, comprising at least a depressed portion having a minimal value Nd of refractive index, a ring portion having a maximal value Nr of refractive index and an outside cladding layer having a maximal value No of refractive index. The optical fiber preform satisfies a relation of Nc?Nr>No>Nd among the values of refractive index. A method of the optical fiber preform comprises fabricating a glass rod by inserting a rod containing at least the central core portion into a pipe containing at least the depressed portion and integrating them, fabricating a glass pipe having the ring portion, and fabricating a vitreous body by integrating the glass rod and the glass pipe by collapsing after inserting the glass rod into the glass pipe.

Abstract: A method of making an optical fibre including providing an increased diameter portion on a rod. The rod is assembled by positioning the rod in a tube such that an annular gap is defined between an outer surface of the rod and an inner surface of the tube, and such that the increased diameter portion of the rod engages the tube and supports the rod with respect to the tube, and supporting the rod and tube assembly by gripping the tube. At the lower end of the rod and tube assembly, portions of the tube are collapsed onto the rod such that the tube portions fuse to the rod forming collapsed portions of the rod and the tube assembly. The collapsed portions are drawn to form an optical fibre. The vertically oriented rod and tube assembly can also be collapsed to form an optical fibre preform.

Abstract: In the known method for producing an optical fiber, a coaxial arrangement comprising a core rod and an outer jacket tube is elongated, the coaxial arrangement being supplied in a vertical orientation to a heating zone and being softened therein zonewise, starting with the lower end thereof, and the optical fiber being withdraw downwards from the softened portion, whereby an annular gap existing between core rod and jacket tube is collapsed. Starting therefrom, in order to provided a method which makes it possible to produce optical fibers with a minimum curl and at low costs, the invention suggests that a quartz glass cylinder treated mechanically to its final dimension and having an outer diameter of at least 100 mm should be used as the jacket tube. An optical fiber obtained according to the method is characterized in that without the action of external forces it assumes a radius of curvature of at least 6 mm.

Abstract: Based on an intermediate 20A in which a cladding portion 22 is formed on the outer periphery of a core portion 21, a pair of holes 23 and 24 are provided parallel to the z axis on both sides of the core portion 21 within the cladding portion 22, and an intermediate 20 is thereby fabricated. In this intermediate 20, a width Ry in the y-axis direction is made smaller than a width Rx in the x-axis direction. Moreover, a cylindrical stress applying part 33 is inserted into a hole 23 of the intermediate 20, and a cylindrical stress applying part 34 is inserted into a hole 24 thereof. Thus, a preform 40 is formed. These materials are drawn and integrated together, and a polarization maintaining optical fiber is thereby manufactured.

Abstract: An object of the present invention is to provide an optical fiber manufacturing method and an optical fiber in which an increase in the transmission loss is suppressed by preventing hydroxyl group from entering near the core portion. This invention provides a method for manufacturing an optical fiber 10 including forming a glass pipe 16 by applying a ring portion 15 on the inner face of a starting pipe 14 as a starting material, inserting a glass rod 13 that becomes a central core portion 11 and a depressed portion 12 into the inside of the glass pipe 16, integrating the glass pipe 16 and the glass rod 13 by collapse to form a glass body 17, forming a preform 10a by providing a jacket portion 18 outside the glass body 17, and drawing the preform 10a, wherein the thickness of the starting pipe 14 is set in a range from 4 mm to 8 mm.

Abstract: Techniques are described for fabricating a preform from a soot body. In one described technique, a soot body is loaded into a substrate tube, and the position of the soot body is stabilized within the tube. The tube is then rotated around its longitudinal axis. Heat is applied from a heat source to the substrate tube at a first end of the soot body to cause the first end of the soot body to begin to sinter and to cause the substrate tube to begin to at least partially collapse around the sintered portion of the soot body. The heat source is then advanced along the substrate tube and the soot body to cause a progressive sintering of the soot body, and to cause a progressive, at least partial, collapse of the substrate tube around the sintered portion of the soot body.

Abstract: The invention relates to a method for manufacture of a quartz glass preform for an optical fibre consisting of the following steps: preparation of a hollow cylinder made of porous quartz glass which exhibits an inner layer with a doping substance which increases the refractive index of quartz glass and an outer layer surrounding the inner layer, with a lower refractive index, and collapse of the hollow cylinder characterised by collapse of the porous hollow cylinder onto a quartz glass rod containing the doping substance.