Abstract: Systems and methods described herein provide a thermally compensated waveguide structure having a thermal index profile configured to correct thermal aberrations caused by temperature gradients in a fast axis direction and/or correct other forms of distortions in an output beam generated by the waveguide structure. The waveguide structure includes a core region, one or more cladding, and one or more heat sinks. A geometry of these portions with respect to each other can provide a cold refractive index profile such that a cold refractive index value of a portion of the core region is less than a cold refractive index value of at least one of the one or more cladding regions. Responsive to thermal compensation, the cold refractive index profile is modified, through addition of a thermal index profile, to form a hot index profile having attributes including good overlap of the fundamental mode with the gain profile and mode clean-up through gain discrimination against higher order modes.

Abstract: Provided is a method for producing an optical fiber preform including a dehydration step and a sintering step. In the dehydration step, a porous glass base material is provided to a furnace core tube of a dehydration-sintering furnace, and the porous glass base material is dehydrated using a dehydration agent added with an argon gas. In the sintering step, the porous glass base material dehydrated in the dehydration step is sintered. Further, in the dehydration step, a temperature of the porous glass base material begins to be increased in a condition such that a high heat conductivity gas, having a heat conductivity higher than a heat conductivity of the argon gas, is remaining inside the porous glass base material.

Abstract: A muffle tube inspection method inspects a muffle tube used for dehydrating and sintering a silica glass-based optical fiber preform, the muffle tube includes a sintering furnace provided with a furnace body covering a heater disposed around a periphery of the muffle tube. The method detects a crack generated at the muffle tube by measuring a pressure inside the furnace body while varying a pressure inside the muffle tube.

Abstract: A method of making optical fibers that includes controlled cooling to produce fibers having a low concentration of non-bridging oxygen defects and low sensitivity to hydrogen. The method may include heating a fiber preform above its softening point, drawing a fiber from the heated preform and passing the fiber through two treatment stages. The fiber may enter the first treatment stage at a temperature between 1500° C. and 1700° C., may exit the first treatment stage at a temperature between 1200° C. and 1400° C., and may experience a cooling rate less than 5000° C./s in the first treatment stage. The fiber may enter the second treatment stage downstream from the first treatment stage at a temperature between 1200° C. and 1400° C., may exit the second treatment stage at a temperature between 1000° C. and 1150° C., and may experience a cooling rate between 5000° C./s and 12,000° C./s in the second treatment stage.

Abstract: A method of manufacturing an optical fiber base material includes: forming a porous glass base material by depositing glass particles; providing a synthetic quartz glass vessel at least partly made of quartz glass which contains aluminum equal to or less than 0.01 ppm; introducing dehydration reaction gas and inert gas into the vessel; heating a portion made of quartz glass which contains aluminum equal to or less than 0.01 ppm in the vessel that contains the dehydration reaction gas and the inert gas; and inserting the porous glass base material into the heated vessel to dehydrate and sinter the porous glass base material.

Abstract: Provided is a method of manufacturing an optical fiber base material having at least four layer including a core, a first cladding, a second cladding containing fluorine, and a third cladding. The manufacturing method comprises preparing a starting base material that includes the core and the first cladding; forming a porous intermediate glass base material by supplying glass raw material and oxygen to a high-frequency induction thermal plasma torch to synthesize glass fine particles that are then deposited on a surface of the starting base material; forming an intermediate glass base material that includes the core, the first cladding, and the second cladding containing fluorine, by heating and vitrifying the porous intermediate glass base material in an atmosphere containing fluorine; and providing the third cladding on the outer surface of the intermediate glass base material.

Abstract: A porous layer is formed by depositing a silica glass particle around a core rod. The porous layer is dehydrated. The dehydrated porous layer is sintered under a decreased pressure until the dehydrated porous layer becomes a translucent glass layer containing a closed pore. The translucent glass layer is vitrified under an ambient atmosphere including an inert gas other than a helium gas.

Abstract: The present invention relates to a method for manufacturing a primary preform for optical fibers, using an internal vapor deposition process, wherein a gas flow of doped undoped glass-forming gases is supplied to the interior of a hollow substrate tube having a supply side and a discharge side via the supply side thereof, wherein deposition of glass layers on the interior of the substrate tube is effected as a result of the presence of a reaction zone.

Abstract: A method for manufacturing an optical fiber preform includes a process A of applying flame polishing to a center glass rod, a process B of determining a ratio ra/rb, which is a ratio of a radius ra of the center glass rod expressed in millimeters with respect to a radius rb of a target optical fiber preform expressed in millimeters, based on a refractive index profile of a target optical fiber preform, and a process C of determining an amount of fine glass particles to be deposited on the center glass rod so that a ratio ra/rb/c falls within a range from 0.002 to 0.01, where “c” is a maximum value of hydroxyl group concentration expressed in ppm in the vicinity of a boundary between the center glass rod and an outer layer, which is formed by depositing fine glass particles on the center rod and by being vitrified.

Abstract: A method of manufacturing an optical fiber base material having very little impurity which deteriorates the transmission characteristic of an optical fiber is provided. The method of manufacturing an optical fiber base material including: producing a core member for the optical fiber base material by dehydrating and transparently vitrifying a base material formed by depositing glass particles; and drawing the core member and then adding a cladding thereto at a desired core to cladding ratio, wherein the dehydrating includes suspending the base material in a furnace tube having a heating region in a first atmosphere at a first temperature, the base material passing through the heating region as upwardly moving, and the transparently vitrifying includes situating the base material below once and then allowing the base material to pass through the heating region in a second atmosphere at a second temperature as upwardly moving again.

Abstract: Photodarkening resistant optical fiber lasing media and fiber lasers incorporating the same are disclosed. In one embodiment, an optical fiber lasing medium includes a core portion formed from silica-based glass comprising a rare-earth dopant and deuterium, the core portion having an index of refraction nc, a numerical aperture NAc. A concentration of defect color centers in the core portion is less than 1×1016/cm3. Deuterium is combined with the defect color centers to form reacted defect color centers that do not absorb ultraviolet and visible wavelengths of light. A first cladding portion is formed from silica-based glass, the first cladding portion surrounding and directly contacting the core portion and having an index of refraction n1, wherein the index of refraction n1 of the first cladding portion is less than the index of refraction nc of the core portion. Methods of forming the photodarkening resistant optical fiber lasing media are also disclosed.

Abstract: A muffle tube inspection method inspects a muffle tube used for dehydrating and sintering a silica glass-based optical fiber preform, the muffle tube includes a sintering furnace provided with a furnace body covering a heater disposed around a periphery of the muffle tube. The method detects a crack generated at the muffle tube by measuring a pressure inside the furnace body while varying a pressure inside the muffle tube.

Abstract: Method for producing a semifinished product from synthetic quartz glass Methods for producing a semifinished product from synthetic quartz glass by plastic deformation of a softened SiO2 mass in a melt mold are known. Starting from this, to avoid fusion defects as much as possible and to obtain semifinished products of quartz glass in a reproducibly high quality, a method is suggested that comprises the following steps: (a) providing a porous SiO2 soot body, (b) zonewise sintering of the SiO2 soot body in the melt mold at a sintering temperature and during a sintering period with formation of a completely sintered transparent quartz glass body, and directly thereafter (c) shaping the sintered quartz glass body by softening in the melt mold with formation of a viscous quartz glass mass which fills the volume of the melt mold entirely or partly, and (d) cooling the quartz glass mass and removing the mass from the melt mold with formation of the semifinished product.

Abstract: A device for contracting a hollow substrate tube made of quartz glass into an optical perform including a heat source movable relative to the longitudinal direction of the substrate tube and an insert tube positioned in the interior of the substrate tube, at one end thereof, provided with a central opening through which a gas is passed and supplied to the interior of the substrate tube.

Abstract: A fused silica glass having a refractive index homogeneity of less or equal to about 5 ppm over an aperture area of at least about 50 cm2. The fused silica glass is also substantially free of halogens and has an adsorption edge of less than about 160 nm. The glass is dried by exposing a silica soot blank to carbon monoxide before consolidation, reducing the combined concentration of hydroxyl (i.e., OH, where H is protium (11H) and deuteroxyl (OD), where D is deuterium (12H)) of less than about 20 ppm by weight in one embodiment, less than about 5 ppm by weight in another embodiment, and less than about 1 ppm by weight in a third embodiment.

Abstract: A known method for producing synthetic quartz glass comprises the method steps: (a) forming a cylindrical SiO2 soot body having an inner portion and at least one free cylinder jacket surface surrounding the inner portion; (b) thermally drying the porous soot body; and (c) vitrifying the dried soot body with formation of the cylinder from synthetic quartz glass.

Abstract: Disclosed is a method of heat treating quartz glass deposition tubes at between 900° C. and 1200° C. for at least 115 hours. The resulting deposition tubes are useful in forming optical preforms that can yield optical fibers having reduced added loss.

Abstract: A method of manufacturing a cylindrical glass optical waveguide preform having a low water content centerline region, for use in the manufacture of optical waveguide fiber, is disclosed. The centerline region of the glass optical waveguide preform has a water content sufficiently low such that an optical waveguide fiber producible from the glass optical waveguide preform of the present invention exhibits an optical attenuation of less than about 0.35 dB/km, and preferably less than about 0.31 dB/km, at a measured wavelength of 1380 nm. Method of manufacture of a porous core mandrel used in the manufacture of such a glass optical waveguide preform is also disclosed.

Abstract: A glass preform manufacturing method includes: generating glass fine particles by hydrolyzing a source gas in an oxyhydrogen flame; depositing the generated glass fine particles to form a torous glass preform; immersing the porous glass preform in an additive solution including an additive solvent in which a compound containing a desired additive is dissolved to impregnate the additive solution into the porous glass preform; first replacing of replacing the additive solvent remaining in the porous glass preform with the replacement solvent by immersing the porous glass preform in which the additive solution remains in a replacement solvent in which a solubility of the additive is lower than that in the additive solvent and having miscibility with the additive solvent; drying the porous glass preform after the first replacing; and sintering the dried porous glass preform to transparently vitrify the dried porous glass preform.

Abstract: Provided is a method for producing an optical fiber preform including a dehydration step and a sintering step. In the dehydration step, a porous glass base material is provided to a furnace core tube of a dehydration-sintering furnace, and the porous glass base material is dehydrated using a dehydration agent added with an argon gas. In the sintering step, the porous glass base material dehydrated in the dehydration step is sintered. Further, in the dehydration step, a temperature of the porous glass base material begins to be increased in a condition such that a high heat conductivity gas, having a heat conductivity higher than a heat conductivity of the argon gas, is remaining inside the porous glass base material.

Abstract: A method for producing a fused silica glass containing titania includes synthesizing particles of silica and titania by delivering a mixture of a silica precursor and a titania precursor to a burner, growing a porous preform by successively depositing the particles on a deposition surface while rotating and translating the deposition surface relative to the burner, and consolidating the porous preform into a dense glass.

Abstract: A method of manufacturing a cylindrical glass optical waveguide preform having a low water content centerline region, for use in the manufacture of optical waveguide fiber, is disclosed. The centerline region of the glass optical waveguide preform has a water content sufficiently low such that an optical waveguide fiber producible from the glass optical waveguide preform of the present invention exhibits an optical attenuation of less than about 0.35 dB/km, and preferably less than about 0.31 dB/km, at a measured wavelength of 1380 nm. Method of manufacture of a porous core mandrel used in the manufacture of such a glass optical waveguide preform is also disclosed.

Abstract: The invention provides a process for producing a synthetic quartz glass, comprising: (a) depositing fine quartz glass particles synthesized by flame hydrolysis of a glass-forming material, on a substrate, to form a porous quartz glass base; (b) presintering the porous quartz glass base; (c) heat-treating the presintered porous quartz glass base by holding it under vacuum at a temperature in the range of from 1,100° C. to below the vitrification temperature for a certain time period; and (d) heating the thus heat-treated porous quartz glass base to a temperature not lower than the vitrification temperature to obtain a synthetic quartz glass. According to the process for synthetic quartz glass production of the invention, a synthetic quartz glass having a reduced OH group amount and a uniform OH group concentration can be obtained. From the synthetic quartz glass, an optical member having excellent optical properties can be obtained.

Abstract: A method for manufacturing an optical fiber preform and an optical fiber preform apparatus are provided which can reduce hydroxyl groups in an optical fiber preform to a sufficient level without requiring any special equipment or operating conditions. When an optical fiber preform is manufactured by the vapor-phase deposition method, the dehydrating treatment is performed on a porous core preform that is obtained by depositing glass microparticles. In this treatment, a dehydrating agent is supplied to a dehydration apparatus through a feeding pipe and a main feeding pipe made of a material having a water permeance factor of 1.0×10?11 g·cm/cm2·s·cmHg or less, thereby manufacturing an optical fiber preform.

Abstract: The invention relates to a method for the manufacture of a lens of synthetic quartz glass with increased H2 content, in particular for a lens for an optical system with an operating wavelength of less than 250 nm, in particular less than 200 nm, with the steps: providing a precursor product of synthetic quartz glass, in particular with a first H2 content of less than 2·1015 molecules/cm3, with a circumferential border surface and two base surfaces lying on opposite sides, wherein at least one partial surface of at least one of said base surfaces has a curvature, and treating the precursor product in an H2-containing atmosphere in order to produce a precursor product of synthetic quartz glass with a second H2 content that is increased in relation to the first H2 content, in particular with a second H2 content of more than 1016 molecules/cm3, and measuring at least one optical property of said precursor product with said second H2 content.

Abstract: A method of manufacturing a cylindrical glass optical waveguide preform having a low water content centerline region, for use in the manufacture of optical waveguide fiber, is disclosed. The centerline region of the glass optical waveguide preform has a water content sufficiently low such that an optical waveguide fiber producible from the glass optical waveguide preform of the present invention exhibits an optical attenuation of less than about 0.35 dB/km, and preferably less than about 0.31 dB/km, at a measured wavelength of 1380 nm. Method of manufacture of a porous core mandrel used in the manufacture of such a glass optical waveguide preform is also disclosed.

Abstract: A method for manufacturing an optical fiber preform and an optical fiber preform apparatus are provided which can reduce hydroxyl groups in an optical fiber preform to a sufficient level without requiring any special equipment or operating conditions. When an optical fiber preform is manufactured by the vapor-phase deposition method, the dehydrating treatment is performed on a porous core preform that is obtained by deposing glass microparticles. In this treatment, a dehydrating agent is supplied to a dehydration apparatus through a feeding pipe and a main feeding pipe made of a material having a water permeance factor of 1.0×10?11 g·cm/cm2·s·cmHg or less, thereby manufacturing an optical fiber preform.

Abstract: A dehydration-sintering furnace includes a core tube configured to dehydrate and sinter a porous base material in fabrication of an optical fiber and having an outlet configured to discharge a vapor. The furnace includes a pressure-variation damper connected to the outlet of the core tube. The furnace includes a trap between the core tube and the pressure-variation damper for collecting the vapor.

Abstract: The present invention provides a method for manufacturing an optical fiber preform, which provides an optical fiber with stable transmission loss characteristics, and improves manufacturing efficiency. The method for manufacturing an optical fiber preform comprises dehydrating the optical fiber soot preform by lowering the optical fiber soot preform within the muffle tube and passing through a heating region, pulling up the dehydrated optical fiber soot preform to the predetermined position, and sintering the optical fiber soot preform by lowering the optical fiber soot preform again within the muffle tube and passing through the heating region where temperature of the heating region is higher than temperature of the heating region in dehydrating; wherein A?B is satisfied where A is pull-up speed (mm/minute) of the optical fiber soot preform during the pulling up and B is gas flow rate (mm/minute) within the muffle tube at room temperature during the pulling up. Furthermore, 1.5×A?B is satisfied.

Abstract: A method of manufacturing an optical fiber base material having very little impurity which deteriorates the transmission characteristic of an optical fiber is provided. The method of manufacturing an optical fiber base material including: producing a core member for the optical fiber base material by dehydrating and transparently vitrifying a base material formed by depositing glass particles; and drawing the core member and then adding a cladding thereto at a desired core to cladding ratio, wherein the dehydrating includes suspending the base material in a furnace tube having a heating region in a first atmosphere at a first temperature, the base material passing through the heating region as upwardly moving, and the transparently vitrifying includes situating the base material below once and then allowing the base material to pass through the heating region in a second atmosphere at a second temperature as upwardly moving again.

Abstract: A known method for producing synthetic quartz glass with a predetermined hydroxyl group content comprises the following steps: a porous SiO2 soot body is produced by flame hydrolysis or oxidation of a silicon-containing start compound and by layerwise deposition of SiO2 particles on a rotating support; the soot body is subjected to a dehydration treatment in a reaction gas-containing drying atmosphere at a drying temperature for removing hydroxyl groups; and the SiO2 soot body is vitrified into a body consisting of the synthetic quartz glass. Starting from this, and in order to permit a reproducible and reliable manufacture of synthetic, UV-radiation resistant quartz glass with predetermined hydroxyl group content and low chlorine content, it is suggested according to the invention that the dehydration treatment according to method step (b) comprises a drying phase during which ozone is used as the reaction gas, whereby the ozone content of the drying atmosphere is between 0.5% by vol. and 10% by vol.

Abstract: An optical fiber processing apparatus comprises reactors (3, 3a, 3b and 3c) that accommodate optical fiber, a single suction pump (7) having an intake port (19) and an outlet port (21), a storage chamber (5) into which deuterium containing gas is delivered, and a circuit portion (9, 59) including a plurality of valves disposed on a plurality of passages connecting the reactors, the suction pump and the storage chamber. The circuit portion includes a first channel for returning deuterium containing gas inside a reactor chamber to the storage chamber, a second channel for delivering air to the reactor chamber thereby rendering the pressure inside the reactor chamber atmospheric pressure, a third channel for decompression of the reactor chamber and a fourth channel for supplying deuterium containing gas in the storage chamber into the reactor chamber.

Abstract: A drawing method for a bare optical fiber, comprises the steps of: melting an optical fiber preform using a heating device and drawing the bare optical fiber; and naturally cooling down the bare optical fiber or forcibly cooling down the bare optical fiber by a cooling device after the heating and melting step, wherein a temperature history during the drawing the optical fiber preform to obtain the bare optical fiber in the heating device satisfies a relational expression: T??0.01X+12 where a time period when the heated and molten portion of the optical fiber preform heated and molten by the heating device reaches 1800° C. or higher is T (min) and a OH group concentration in a cladding layer of the optical fiber preform is X (wtppm).

Abstract: Embodiments of the invention include a method for making optical fiber having reduced aging or hydrogen aging loss over the life of the fiber and optical fiber systems including such optical fibers. Improved silicon-oxygen stoichiometry during one or more preform manufacturing steps reduces the amount of Si defects generated in the optical fiber preform. Also, deuterium exposure of optical fiber drawn from the preform reduces the likelihood of having atomic defects such as Si defects in the optical fiber that, over time, attract and bond with hydrogen atoms to form molecules that contribute to increased water absorption loss. The inventive method produces optical fibers with improved transmission characteristics, e.g., optical fibers made by methods according to embodiments of the invention have transmission loss at 1385 nanometers that is less than 0.33 dB/km and the aging loss increase thereafter is less than 0.04 dB/km.

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: The present invention provides a synthetic quartz glass having a diameter of 100 mm or more for using in an optical apparatus comprising a light source emitting a light having a wavelength of 250 nm or less, the synthetic quartz glass having, in a region located inward from the periphery thereof by 10 mm or more in a plane perpendicular to the optical axis of the synthetic quartz glass: a birefringence of 0.

Abstract: A method for manufacturing an optical fiber having uniform refractive index profile, and substantially reduced macrobending loss and attenuation loss is provided comprising controlling one or more of parameters including concentration of dopant in outer region and inner region of the core region with respect to middle region of the core region of the optical fiber preform, duration of dehydration process step, concentration of chlorine gas to control refractive index of outer region and inner region of the core region for achieving a fiber having substantially uniform refractive index profile, and substantially reduced macrobending loss and attenuation loss.

Abstract: A method for producing optical fiber having reduced hydrogen induced loss is provided wherein the optical fiber is treated with deuterium gas for a predetermined duration. The predetermined duration of deuterium treatment is determined based on three factors, that is, a) the concentration of deuterium at which fiber is to be treated with deuterium; b) the reaction temperature at which fiber is to be treated with deuterium; and c) the pressure inside the chamber at which fiber is to be treated with deuterium.

Abstract: A method for deposition glass soot for making an optical fiber preform. A fuel and a glass precursor are flowed to a burner flame forming glass soot which is deposited onto a glass target. By first depositing an insulating layer of glass soot with a low velocity burner flame, the amount of water which may be adsorbed into the surface of the glass target can be reduced. Thereafter, the flame velocity may be increased to increase the deposition rate of the glass soot without significantly increasing the concentration of water incorporated into the glass target.

Abstract: Disclosed is a low-attenuation single-mode optical fiber having a photoconductive core and a clad, which shows very low OH concentration in MFD (Mode Field Diameter) region. The optical fiber includes a core positioned at its center for photoconduction, and a dehydrated clad and a base clad which are coated on the clad in order. The dehydrated clad has a substantially identical refractive index to the base clad. A refractive index of the core is greater than those of the dehydrated clad and the base clad. The dehydrated clad has a relatively lower OH concentration than the base clad. The region composed of the core and the dehydrated clad has an MFD region at which OH concentration is less than 0.8 ppb.

Abstract: A plurality of optical fibers are bundled, and the fiber bundle is cut at a part of a mouthpiece which is fixed on an intermediate part of the fiber bundle. Thus, the fiber bundle is divided into a first optical fiber bundle and a second optical fiber bundle. Division surfaces of the first and second optical fiber bundles have the same properties and condition since the first and second optical fiber bundles are formed of the fiber bundle that is obtained by bundling the same optical fibers. The first optical fiber bundle is assembled in an insertion section of an endoscope and the second optical fiber bundle is assembled in a flexible tube, and a first light guide in the insertion section of the endoscope and a second light guide in the flexible tube are formed. Thereby, a separable light transmission path of the light guide is formed.

Abstract: An optical fiber having a cladding region surrounding a core region having an elongate core hole, the inner or outer surface of the core hole having a surface roughness with a spatial period equal to or less than 5 ?m by a spectral power below 0.0017 nm2 ?m?1. A method of making an optical fiber including a cladding region having an arrangement of elongate cladding holes in a matrix material, surrounding an elongate core region having an elongate core hole, the method including the step of increasing the surface tension of the matrix material prior to or during the step of heating and drawing the fiber.

Abstract: A known method for producing synthetic quartz glass with a predetermined hydroxyl group content comprises the following steps: a porous SiO2 soot body is produced by flame hydrolysis or oxidation of a silicon-containing start compound and by layerwise deposition of SiO2 particles on a rotating support; the soot body is subjected to a dehydration treatment in a reaction gas-containing drying atmosphere at a drying temperature for removing hydroxyl groups; and the SiO2 soot body is vitrified into a body consisting of the synthetic quartz glass. Starting from this, and in order to permit a reproducible and reliable manufacture of synthetic, UV-radiation resistant quartz glass with predetermined hydroxyl group content and low chlorine content, it is suggested according to the invention that the dehydration treatment according to method step (b) comprises a drying phase during which ozone is used as the reaction gas, whereby the ozone content of the drying atmosphere is between 0.5% by vol. and 10% by vol.

Abstract: Disclosed is a method for fabricating an optical fiber preform. The method includes: (a) growing a first soot preform on a starting member along a lengthwise direction of the starting member by a soot deposition; (b) dehydrating the first soot preform; (c) sintering the dehydrated first soot preform, to obtain a first glassed optical preform; and (d) elongating the first optical fiber preform by heating the first optical fiber with a heat source that excludes hydrogen, wherein the first glassed optical fiber is elongated by means of only a heat source that excludes the use of hydrogen.

Abstract: Disclosed are a method for fabricating an optical fiber preform and a method for fabricating an optical fiber using the optical fiber preform. The method for fabricating the optical fiber preform including the steps of: (a) growing a first soot preform on a starting member by a soot deposition; (b) dehydrating the first soot preform; (c) sintering the first dehydrated soot preform to obtain a first glassed optical fiber perform; (e) growing an over-clad soot layer on the first optical fiber preform by soot deposition to obtain a second soot preform; and (f) sintering the second soot preform so as to obtain a second optical fiber preform which is glassed, wherein an average density of the first soot preform is substantially within a range of 0.19˜0.30 g/cc, and the average density of the over-clad soot layer is substantially within a range of 0.5˜0.75 g/cc.

Abstract: A method produces a glass body that contains a reduced amount of OH groups in the metallic-oxide-containing glass layer and that has a reduced amount of transmission loss due to OH groups when the glass body is transformed into an optical fiber. The production method produces an optical glass body. An optical fiber contains the optical glass body in at least one part of its region for guiding a lightwave. The production method includes the following steps: (a) introducing into a glass pipe a gas containing an organometallic compound and a glass-forming material; (b) decomposing the organometallic compound into an organic constituent and a metallic constituent; (c) heating and oxidizing the metallic constituent so that produced glass particles containing a metallic oxide are deposited on the inner surface of the glass pipe to form a glass-particle-deposited layer; and (d) consolidating the deposited layer to form a metallic-oxide-containing glass layer.

Abstract: An object of the present invention is to overcome the problems of the prior art technique, and to provide a heat treatment method as well as a heat treatment apparatus capable of heat treating, with higher efficiency, a synthetic quartz glass for optical use having higher homogeneity and higher purity. Another object of the present invention is to provide and a synthetic quartz glass for optical use.

Abstract: Optical waveguide fiber having low water peak as well as optical waveguide fiber preforms and methods of making optical waveguide fiber preforms from which low water peak and/or low hydrogen aged attenuation optical waveguide fibers are formed, including optical waveguide fiber and preforms made via OVD. The fibers may be hydrogen resistant, i.e. exhibit low hydrogen aged attenuation. A low water peak, hydrogen resistant optical waveguide fiber is disclosed which exhibits an optical attenuation at a wavelength of about 1383 nm which is less than or equal to an optical attenuation exhibited at a wavelength of about 1310 nm.

Abstract: The present invention provides a method of fabricating rare earth doped preforms and optical fibers by a combination of modified chemical vapor deposition (MCVD) process and solution doping technique said MCVD process is used to develop matched or depressed clad structure inside a silica glass substrate tube followed by deposition of porous silica soot layer containing GeO2, P2O5 or such refractive index modifiers by the backward deposition method for formation of the core and presintering the deposited particulate layer by backward pass with flow of GeCl4 and/or corresponding dopant halides, soaking the porous soot layer into an alcoholic/aqueous solution of RE-salts containing codopants such as AlCl3 in definite proportion, drying, oxidation, dehydration and sintering of the RE containing porous deposit and by collapsing at a high temperature to produce the preform followed by drawing the fibers by known technique to produce fibers with suitable core-clad dimensions and geometry.

Abstract: A dehydration and consolidation furnace and a dehydration and consolidation method in which gas in a chamber does not leak to a furnace body room and gas in a furnace body room does not leak into a chamber is provided. A furnace of one embodiment of this invention has first muffle tube 3 and second muffle tube 4. The second muffle tube 4 is arranged coaxially around the first muffle tube 3. An optical fiber preform is arranged in this furnace. During the dehydration and consolidation process the pressure of the intermediate room 10 is set lower than a pressure inside the first muffle tube and outside the second muffle tube, and a gas supply and exhaust of the intermediate room 10 are performed independent of the gas supply and exhaust of the first muffle tube and a furnace body room.