Abstract: A machine accesses a stored dataset comprising, for each of multiple optical fiber preforms, a plurality of images of each optical fiber preform coupled with an indication of a number of fiber kilometers lost due to diameter upset of a cable built using optical fiber drawn from the optical fiber preform. Each image represents a portion of the optical fiber preform. The machine preprocesses the stored dataset to generate a training dataset. The machine trains, using the training dataset, a convolutional neural network (CNN) to predict diameter upset performance of an optical fiber preform based on visual information representing the optical fiber preform. The CNN comprises an input layer, a plurality of hidden layers, and an output layer. Each of the input layer and the plurality of hidden layers comprises a plurality of artificial neurons. The machine provides an output representing the trained CNN.

Abstract: A multicore fiber includes: n pieces of first core regions in a circular shape with a radius r1 that are arranged about points P11 to P1n, and that has a first core portion and a first cladding portion; a second core region in a circular shape with a radius R1 that is arranged about the point a1, and that has a second core portion and a second cladding portion; and a cladding region that is formed on an outer circumferences of the first core region and the second core region. Further, abutting surfaces that are flat surfaces abutting on each other are formed in portions on the outer circumferences of the first core region and the second core region.

Abstract: An optical fiber preform production method includes: inserting at least one glass rod into at least one through-hole that penetrates a cladding glass body that is a cladding of an optical fiber; integrating a dummy rod by either integrating a solid dummy silica rod with a first end of the cladding glass body by heating the first end to close a first opening of the through-hole that opens in the first end, or forming a base end seal that closes the first opening in the first end and integrating the solid dummy silica rod with the base end; and closing a second opening of the through-hole that opens in a second end of the cladding glass body by heating and deforming the second end.

Abstract: An apparatus for producing large glass preforms with minimal clad to-core waveguide distortion from a glass body having a weight, an outer surface, core rods, and a cladding surrounding and separated from the core rods by a gap. The apparatus includes collars affixed to the top and bottom of the cladding; a spacer upon which the core rods rest; a first unit holding and supporting both the bottom collar and the spacer; a second unit holding and supporting the top collar; and a frame defining a heating zone having a heating element to heat the glass body. The weight of the glass body above and below the molten glass in the heating zone is supported by the first and second units without contacting the outer surface of the glass body.

Abstract: According to embodiments, a method of making a microstructured glass article includes bundling M bare optical fibers in a fiber bundle, wherein M is an integer greater than 100. Thereafter, the fiber bundle may be inserted in a cavity of a soot preform. The soot preform may have a density of less than or equal to 1.5 g/cm3 and comprise silica-based glass soot. The soot preform and inserted fiber bundle may then be consolidated to form a microstructured glass article preform. The microstructured glass article preform may then be drawn into the microstructured glass article comprising M core elements embedded in a cladding matrix.

Abstract: A side fire optical fiber tip is provided for use in high power laser applications having outputs of greater than or equal to 50 Watts. A predetermined length of an output tip on the distal end of the optical fiber is formed with an optical fiber core and cladding layer of preselected thickness wherein the cladding to core diameter ratio is at least as great as 1.2. A side fire surface is formed on the distal end of the core/clad output end. Over this optical fiber output end, a pure silica capillary tube is fused to the predetermined length of exposed cladding where the outermost cladding is also pure silica to reduce thermal mismatch during the fusion process. By having the refractive index at the fusing interface matched, and bubbles or gaps eliminated or prevented, it is possible to substantially eliminate Fresnel reflection losses at this interface.

Abstract: There is provided a method for producing a multicore optical fiber while depressurizing holes in a common cladding tube. A production method for a multicore optical fiber includes a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an end-face working step of digging the common cladding tube from the second end to a predetermined depth to forming a third end, a connection step of connecting a glass tube to the second end, an insertion step of inserting core rods into the holes to the third end, a sealing step of sealing the first end, and a drawing step of spinning the multicore optical fiber while depressurizing the holes through the glass tube and combining the common cladding tube and the core rods from the first end.

Abstract: There is provided a method for producing a multicore optical fiber while reducing the mass of a glass block to be connected to a common cladding tube. A production method for a multicore optical fiber includes in order, a preform forming step of forming a common cladding tube having a plurality of holes extending between a first end and a second end, an insertion step of inserting core rods in the holes in a state in which end portions of the core rods are recessed from the first end, a heat shrinkage step of reducing a diameter of the first end by heating, a sealing step of sealing the holes by connecting a glass block to the first end, and a drawing step of depressurizing insides of the holes from the second end and performing spinning from the first end while combining the common cladding tube and the core rods.

Abstract: In one general aspect, a system for determining a motion of an object includes a laser system configured to generate range and velocity measurements of a plurality of points on the object and a processor. The processor is configured to determine, from the range and velocity measurements of the plurality of points on the object, a rotation of the object. In some aspects, the processor is also configured to determine, from the range and velocity measurements of the plurality of points on the object and the rotation of the object, a distance moved by the object between a first time and a second time.

Abstract: Methods for producing glass components and obtainted glass component, e.g. optical fiber preform. A method includes providing a cladding tube (110) with a longitudinal axis including a first and a second bore separated by a chamfered region (114); inserting a spacer (120) into the first bore; inserting a rod (130) into the first bore (116); moving the spacer (120) into the chamfered section (114), causing the spacer (120) to rotate within the chamfered region (114); and rotating the cladding tube (110) into a vertical orientation, whereby the spacer (120) is prevented from entering the second bore (118) and supports the rod (130). Each portion of the chamfered region has a height perpendicular to the longitudinal axis greater than the height of the second bore.

Abstract: An optical fiber package is described comprising a light transmitting core having a core diameter, a coating layer surrounding the core, and wherein the amount of chlorine in the light transmitting core region is homogeneous and comprises at least 3000 ppm. The fiber package is such that the optical fiber core exhibits a reduction in the hydrogen induced attenuation losses. A method for fabricating the optical fiber package is also disclosed.

Abstract: A method of forming an optical fiber includes the steps of forming a silica-based soot blank with at least one silica-based soot core cane at least partially embedded in the soot blank. The soot blank with the soot core cane positioned therein is consolidated to form a preform. The preform is then drawn to form an optical fiber. The soot core cane preferably has an average bulk density within 10% of the bulk density of the soot blank, and more preferably within 5% of the bulk density of the soot blank.

Abstract: Tapered core fibers are produced using tapered core rods that can be etched or ground so that a fiber cladding has a constant diameter. The tapered core can be an actively doped core, or a passive core. One or more sleeving tubes can be collapsed onto a tapered core rod and exterior portions of the collapsed sleeving tubes can be ground to provide a constant cladding diameter in a fiber drawn from the preform.

Abstract: Multi-core optical fiber ribbons and methods for making multi-core optical fiber ribbons are described herein. In one embodiment, a multi-core optical fiber ribbon includes at least two core members formed from silica-based glass and oriented in parallel with one another in a single plane. Adjacent core members have a center-to-center spacing ?15 microns and a cross-talk between adjacent core members is ??25 dB. In this embodiment each core member is single-moded with an index of refraction nc, and a core diameter dc. In an alternative embodiment, each core member is multi-moded and the center-to-center spacing between adjacent core members is ?25 microns. A single cladding layer is formed from silica-based glass and surrounds and is in direct contact with the core members. The single cladding layer is substantially rectangular in cross section with a thickness ?400 microns and an index of refraction ncl<nc.

Abstract: An apparatus used for the fabrication of fiberoptic waveguides utilizing a novel melting and resolidifying apparatus and method while under microgravity conditions is disclosed. In one embodiment, the optical fiber core has a lower melting point than the cladding and the core is melted and resolidified under microgravity conditions. The molten lower melting point core is thus contained by the higher melting point cladding while under microgravity conditions.

Abstract: A method of manufacturing an optical fiber preform includes: producing a core rod having a core rod diameter; inserting the core rod into a glass fluorine-doped intermediate cladding tube so as to form a core assembly, the intermediate cladding tube having an inner diameter and an outer diameter, wherein the inner diameter is larger than the core rod diameter, the radial difference between the inner diameter and the core rod diameter defining an annular gap; and applying a negative pressure inside the annular gap; and forming a core preform by heating the core assembly to collapse the intermediate cladding tube around the core rod while maintaining the negative pressure, wherein heating includes moving a heater outside the intermediate cladding tube and along an axial direction of the same, and forming an overcladding region surrounding the core preform so as to form an optical fiber preform.

Abstract: A method of manufacturing an optical fiber preform or an optical fiber is provided. The method includes the steps of: (a) providing a glass tube and a glass core rod; (b) inserting the glass core rod into the glass tube to form an assembled body; (c) heating the assembled body to cause the glass tube to collapse on and adhere to the glass core rod; and (d) treating an interface gap between the glass core rod and the glass tube during heating of at least a portion of the assembled body. Treating of the interface gap involves: (i) establishing a vacuum pressure in the interface gap, (ii) increasing a pressure of the interface gap by a treatment gas through the interface gap for a predetermined time, and (iii) re-establishing a vacuum pressure in the interface gap after the predetermined time has elapsed.

Abstract: The present invention relates to a double cladding crystal fiber and manufacturing method thereof, in which growing an YAG or a sapphire into a single crystal fiber by LHPG method, placing the single crystal fiber into a glass capillary for inner cladding, placing the single crystal fiber together with the glass capillary for inner cladding into a glass capillary for outer cladding in unison, heating the glass capillary for inner cladding and outer cladding by the LHPG method to attach to the outside of the single crystal fiber, and thus growing into a double cladding crystal fiber. When the present invention is applied to high power laser, by using the cladding pumping scheme, the high power pumping laser is coupled to the inner cladding layer, so the problems of heat dissipation and the efficiency impairment due to energy transfer up-conversion of high power laser are mitigated.

Abstract: Light-coupling apparatus and methods for light-diffusing optical fibers are disclosed. The light-coupling apparatus includes a light-diffusing fiber bundle having an end section made up of tightly packed cores by removing the claddings. The spaces between the cores are filled with a material having a refractive index equal to or less than that of the cores. A light-emitting diode light source can be butt-coupled to the bundled-core end of the light-diffusing fiber bundle or can be coupled thereto via a reflective concentrator. A method of forming a flat and smooth end on a cleaved fiber that has a rough end is also disclosed.

Abstract: Manufacturing an optical fiber by using an outside vapor deposition technique for making a substrate, applying one or more layers to the substrate using a radial pressing technique to form a soot blank, sintering the soot blank in the presence of a gaseous refractive index-modifying dopant, and drawing the sintered soot blank, provides a more efficient and cost effective process for generating complex refractive index profiles.

Abstract: A multicore fiber 1 includes a plurality of cores 3 disposed at predetermined intervals and surrounded by a cladding 5. The multicore fiber 1 also includes a marker 7 formed apart from the cores 3. The refractive index of the marker 7 is different from those of the cores 3 and the cladding 5. For example, the marker 7 may be made of a material having lower refractive index than that of the cladding 5. In this case, for example, the cores 3 may be made of germanium-doped quartz. The cladding 5 may be made of pure quartz. The marker 7 may be made of fluorine-doped quartz. Further, the marker 7 may be an empty hole.

Abstract: A method for manufacturing an optical fiber preform that includes preparing a glass cylinder with inner and outer surfaces forming at least part of a cladding portion are repeatedly polished, and a glass core rod that includes a core portion having a higher refractive index than the cladding portion; and inserting the core rod into the glass cylinder and heating the glass cylinder and core rod to form a single body. The repeated polishing of the inner surface of the glass cylinder includes passing pure water that does not contain a cutting fluid over the inner surface for at least the final polishing. The polishing is preferably performed using a polishing cloth to which are affixed diamond abrasive grains. The glass core rod and the glass cylinder are preferably formed of composite quartz glass.

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 one embodiment, an apparatus may include an optical fiber that may have a surface non-normal to a longitudinal axis of a distal end portion of the optical fiber. The surface may define a portion of an interface configured to redirect electromagnetic radiation propagated from within the optical fiber and incident on the interface to a direction offset from the longitudinal axis. The apparatus may also include a doped silica cap that may be fused to the optical fiber such that the surface of the optical fiber may be disposed within a cavity defined by the doped silica cap.

Abstract: An apparatus for mixing a vaporized precursor with a gas for producing silica particles is provided. The apparatus includes a mixer housing, a precursor delivery chamber having an output in communication with the mixer housing for delivering a vaporized precursor in the mixer housing, and an oxidizing gas delivery chamber having an output in communication with the mixer housing for delivering an oxidizing gas to be mixed with the vaporized precursor. The apparatus further includes a flashback member disposed within the mixer housing and between the output of the precursor delivery chamber and the output of the oxidizing gas delivery chamber. The flashback member is located at a minimum distance from the output of the oxidizing gas delivery chamber defined by Lminimum (cm)=0.453 U (Re)?0.5567, wherein U is the flow rate in cm/sec of precursor and Re is the flow Reynolds number. The flashback member may include a tapered surface on at least one side to reduce recirculation of vaporized gas.

Abstract: The present disclosure is directed to optical fibers having glass buffers. As such, some embodiments comprise an optical fiber having a core, a cladding, and a glass buffer. For some embodiments, the glass buffer has an index of refraction that is greater than the index of refraction of the cladding.

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: A method of assembling a preform for a bend-insensitive multimode optical fiber (BIMMF), includes providing a multimode core rod, a glass overclad tube, and a trench tube of down-doped quartz glass with a depressed refractive index sufficient to obtain a desired trench depth in a refractive index (RI) profile of a drawn fiber. The core rod is placed inside the trench tube, and the trench tube and the core rod are placed inside the overclad tube to define the preform. A top end of the trench tube is formed to contact an adjacent part of either the core rod or the overclad tube so that the trench tube is suspended to hang from the adjacent part when the preform is vertically oriented, and a bottom end of the trench tube is restrained from sinking into a lower portion of the preform when the preform is heated to collapse.

Abstract: A method of manufacturing an optical fiber preform or an optical fiber is provided. The method includes the steps of: (a) providing a glass tube and a glass core rod; (b) inserting the glass core rod into the glass tube to form an assembled body; (c) heating the assembled body to cause the glass tube to collapse on and adhere to the glass core rod; and (d) treating an interface gap between the glass core rod and the glass tube during heating of at least a portion of the assembled body. Treating of the interface gap involves: (i) establishing a vacuum pressure in the interface gap, (ii) increasing a pressure of the interface gap by a treatment gas through the interface gap for a predetermined time, and (iii) re-establishing a vacuum pressure in the interface gap after the predetermined time has elapsed.

Abstract: Methods to fabricate an optical preform for draw into Polarization Maintaining (PM) or Polarizing (PZ) optical fiber are provided. The methods involve assembly of pre-shaped and pieced together bulk glass elements into preforms (“assembled preforms”) for simultaneous fusing and drawing into optical fiber. These preforms form a stress-induced birefringent optical core when drawn to fiber.

Abstract: In a method of cleaning a fiber cap of a laser probe tip, a glass fiber comprising a cap body having an internal cavity and an opening to the cavity at a proximal end is provided. A particulate collecting member is also provided. An electrical charge is applied to the particulate collecting member. A distal end of the particulate collecting member is then inserted through the opening and into the cavity of the fiber cap. Particles located within the cavity are attracted to the particulate collecting member. The attracted particles attach to the particulate collecting member. The particulate collecting member is then removed from the cavity.

Abstract: A method of manufacturing an optical fibre preform includes: producing a core rod having a core rod diameter; inserting the core rod into a glass fluorine-doped intermediate cladding tube so as to form a core assembly, the intermediate cladding tube having an inner diameter and an outer diameter, wherein the inner diameter is larger than the core rod diameter, the radial difference between the inner diameter and the core rod diameter defining an annular gap; and applying a negative pressure inside the annular gap; and forming a core preform by heating the core assembly to collapse the intermediate cladding tube around the core rod while maintaining the negative pressure, wherein heating includes moving a heater outside the intermediate cladding tube and along an axial direction of the same, and forming an overcladding region surrounding the core preform so as to form an optical fibre preform.

Abstract: Methods for making a preform for a large diameter optical waveguide such as a cane waveguide are disclosed. The method includes inserting a preform into a glass tube to serve as cladding that provides a thickened preform, simultaneously fusing and stretching the thickened preform, sectioning the stretched and still thickened preform and repeating the procedure if necessary to provide an even further thickened preform. The drawing apparatus can be configured to work with the preform disposed either horizontally or vertically and usually includes a graphite resistance furnace. Typically, the drawing apparatus is an upper portion of a draw tower used for drawing an optical fiber from an optical fiber preform. The draw tower includes a tractor pulling mechanism that can adjust to grip a wide range of diameters.

Abstract: Provided is a method for manufacturing an optical fiber that is inserted into an insertion portion of an endoscope and guides light, wherein inside an upright fiber drawing furnace, inside a hollow clad tube including a clad glass having a viscosity ?1 of 5.0<Log ?1<7.0 at a temperature at which a viscosity ?2 of a core glass becomes Log ?2=3.5, the core glass in a fluidized state runs down by gravity, whereby the core glass and the clad glass are integrated.

Abstract: Various embodiments include photonic bandgap fibers (PBGF). Some PBGF embodiments have a hollow core (HC) and may have a square lattice (SQL). In various embodiments, SQL PBGF can have a cladding region including 2-10 layers of air-holes. In various embodiments, an HC SQL PBGF can be configured to provide a relative wavelength transmission window ??/?c larger than about 0.35 and a minimum transmission loss in a range from about 70 dB/km to about 0.1 dB/km. In some embodiments, the HC SQL PBGF can be a polarization maintaining fiber. Methods of fabricating PBGF are also disclosed along with some examples of fabricated fibers. Various applications of PBGF are also described.

Abstract: A method and an apparatus for making an optical fiber preform comprising the steps of (i) depositing a plurality of rods are deposited into an inner cavity of an apparatus; (ii) depositing particulate glass material in the inner cavity between the rods and the inner wall; and (iii) applying pressure against the particulate glass material to pressurize the particulate glass material against the plurality of rods.

Abstract: In one embodiment, an apparatus may include an optical fiber that may have a surface non-normal to a longitudinal axis of a distal end portion of the optical fiber. The surface may define a portion of an interface configured to redirect electromagnetic radiation propagated from within the optical fiber and incident on the interface to a direction offset from the longitudinal axis. The apparatus may also include a doped silica cap that may be fused to the optical fiber such that the surface of the optical fiber may be disposed within a cavity defined by the doped silica cap.

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: Method for manufacturing optical fibers, comprising cutting mirror-symmetrical grooves (2, 3) on a preform rod (1) which is inserted into a tube (4) of optical material; fusing the perform rod and the tube in a nonworking area; pulling the fused perform rod and tube into a perform which has longitudinal channels defined by the grooves (2, 3) and the tube (4); cutting the perform (5) into segments; etching the longitudinal channels; sealing segment end(s), assembling segments with a capillary tube and tubular process holder; joining the segment and capillary tube on a side opposite to the tubular process holder; drawing the perform segment into an optical fiber, and applying a protective strengthening coating on the drawn optical fiber. As a result, an optical fiber is produced, which has birefringent properties influenced by dimensions of the mirror-symmetrical grooves and the etching step.

Abstract: A deterministic methodology is provided for designing optical fibers that support field-flattened, ring-like higher order modes. The effective and group indices of its modes can be tuned by adjusting the widths of the guide's field-flattened layers or the average index of certain groups of layers. The approach outlined here provides a path to designing fibers that simultaneously have large mode areas and large separations between the propagation constants of its modes.

Abstract: Described are multi-tube fabrication techniques for making an optical fiber that is relatively insensitive to bend loss and alleviates the problem of catastrophic bend loss comprises a core region and a cladding region configured to support and guide the propagation of light in a fundamental transverse mode. The cladding region includes (i) an outer cladding region, (ii) an annular pedestal (or ring) region, (iii) an annular inner trench region, and (iv) an annular outer trench region. The pedestal region and the outer cladding region each have a refractive index relatively close to that of the outer cladding region. In order to suppress HOMs the pedestal region is configured to resonantly couple at least one (unwanted) transverse mode of the core region (other than the fundamental mode) to at least one transverse mode of the pedestal region.

Abstract: Methods to fabricate an optical preform for draw into Polarization Maintaining (PM) or Polarizing (PZ) optical fiber are provided. The methods involve assembly of pre-shaped and pieced together bulk glass elements into preforms (“assembled preforms”) for simultaneous fusing and drawing into optical fiber. These preforms form a stress-induced birefringent optical core when drawn to fiber.

Abstract: Various embodiments include photonic bandgap fibers (PBGF). Some PBGF embodiments have a hollow core (HC) and may have a square lattice (SQL). In various embodiments, SQL PBGF can have a cladding region including 2-10 layers of air-holes. In various embodiments, an HC SQL PBGF can be configured to provide a relative wavelength transmission window ??/?c larger than about 0.35 and a minimum transmission loss in a range from about 70 dB/km to about 0.1 dB/km. In some embodiments, the HC SQL PBGF can be a polarization maintaining fiber. Methods of fabricating PBGF are also disclosed along with some examples of fabricated fibers. Various applications of PBGF are also described.

Abstract: A method is provided for forming an optical fiber amplifier. The method comprises providing a composite preform having a gain material core that includes one or more acoustic velocity varying dopants to provide a longitudinally varying acoustic velocity profile along the gain material core to suppress Stimulated Brillouin Scattering (SBS) effects by raising the SBS threshold and drawing the composite preform to form the optical fiber amplifier.

Abstract: A method for producing an optical fiber preform according to the present invention includes a collapse step of collapsing a silica-based glass tube by heating with a heat source continuously traversed in the longitudinal direction of the glass tube to form a first glass rod to be formed into a core part or part of a core part of an optical fiber, the glass tube having an inner surface doped with an alkali metal, in which the glass tube has a maximum alkali metal concentration of 500 to 20,000 atomic ppm, a maximum chlorine concentration of 0 to 1000 atomic ppm, and a maximum fluorine concentration of 0 to 10,000 atomic ppm, and in which in the collapse step, the maximum temperature of the outer surface of the glass tube is 2000° C. to 2250° C., and the traverse speed of the heat source is 30 mm/min to 100 mm/min.

Abstract: A method for manufacturing an optical fiber preform that includes preparing a glass cylinder with inner and outer surfaces forming at least part of a cladding portion are repeatedly polished, and a glass core rod that includes a core portion having a higher refractive index than the cladding portion; and inserting the core rod into the glass cylinder and heating the glass cylinder and core rod to form a single body. The repeated polishing of the inner surface of the glass cylinder includes passing pure water that does not contain a cutting fluid over the inner surface for at least the final polishing. The polishing is preferably performed using a polishing cloth to which are affixed diamond abrasive grains. The glass core rod and the glass cylinder are preferably formed of composite quartz glass.

Abstract: An optical fiber that is relatively insensitive to bend loss and alleviates the problem of catastrophic bend loss comprises a core region and a cladding region configured to support and guide the propagation of light in a fundamental transverse mode. The cladding region includes (i) an outer cladding region, (ii) an annular pedestal (or ring) region, (iii) an annular inner trench region, and (iv) an annular outer trench region. The pedestal region and the outer cladding region each have a refractive index relatively close to that of the outer cladding region. In order to suppress HOMs the pedestal region is configured to resonantly couple at least one (unwanted) transverse mode of the core region (other than the fundamental mode) to at least one transverse mode of the pedestal region. In a preferred embodiment, the fiber is configured so that, at a signal wavelength of approximately 1550 nm, its bend loss is no more than about 0.1 dB/turn at bend radius of 5 mm and is no more than about 0.

Abstract: Core rod sections useable for production of finished optical fiber preforms are fabricated by inserting one or more core body pieces axially end-to-end inside a glass cylinder, thereby defining joints between adjacent ones of the inserted pieces. The cylinder is mounted with the contained core body pieces in the region of a furnace. The glass cylinder and core body pieces are heated together in the furnace, thereby elongating the cylinder and the core body pieces contained in the cylinder, and the cylinder collapses to form a finished core rod. Core rod sections are cut from the finished core rod at positions that coincide with the joints between the core body pieces. One or more of the cut core rod sections are useable for the production of optical fiber preforms.

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: In a conventional method for the production of an optical component made from quartz glass, a coaxial arrangement with a core rod, surrounded by a quartz glass envelope tube comprising an evacuable inner drilling, is introduced in the vertical direction into a heating zone, softened therein by sections and, with formation of a drawing bulb, elongated to give the quartz glass component. According to the invention, a simple and cheap method based on the above, permitting the production of high-grade optical components by elongation of a coaxial arrangement of core rod and an enveloping tube with great economy, may be achieved, whereby a core rod is used, comprising at least two separate core rods arranged one above the other in the inner drilling and the weight of an upper core rod section is taken by a mounting or support region of the enveloping tube, provided above the drawing bulb.