Abstract: An IR supercontinuum source for generating supercontinuum in the MIR or possibly LWIR spectral bands comprises a supercontinuum fiber formed from a heavy metal oxide host glass having low optical loss and high non-linearity over the spectral band that is stable, strong and chemically durable. The supercontinuum fiber is suitably a depressed inner clad fiber configured to support only single transverse spatial mode propagation of the pump signal and supercontinuum. The source suitably includes a tapered depressed inner clad fiber to couple the pump signal into the supercontinuum fiber. The source may be configured as an “all-fiber” source.

Abstract: A known method for producing synthetic quartz glass comprises: (a) reacting a carbonic silicon compound-containing raw material with oxygen in a reaction zone into SiO2 particles, (b) precipitating the SiO2 particles on a sedimentation area by forming a porous SiO2 soot body containing hydrogen and hydroxyl groups, (c) drying the porous SiO2 soot body, and (d) glazing to the synthetic quartz glass by heating the soot body up to a glazing temperature. In order to facilitate cost-efficient production of quartz glass by means of pyrolysing or hydrolysing a carbon-containing silicon compound using a carbon-containing raw material, the invention describes the production of a soot body with a carbon content within the range of 1 ppm by weight to 50 ppm by weight.

Abstract: An optical device including an active core layer of silica glass doped with ions which serve as optical emitters, the active core layer being on a silica glass substrate and having a layer thickness of at least 5 ?m, and wherein the layer is sintered at a temperature range of 1500-1600 C. and subsequently heat treated by a laser.

Abstract: An IR supercontinuum source for generating supercontinuum in the MIR or possibly LWIR spectral bands comprises a supercontinuum fiber formed from a heavy metal oxide host glass having low optical loss and high non-linearity over the spectral band that is stable, strong and chemically durable. The supercontinuum fiber is suitably a depressed inner clad fiber configured to support only single transverse spatial mode propagation of the pump signal and supercontinuum. The source suitably includes a tapered depressed inner clad fiber to couple the pump signal into the supercontinuum fiber. The source may be configured as an “all-fiber” source.

Abstract: A tellurium oxide glass that is stable, strong and chemically durable exhibits low optical loss from the UV band well into the MIR band. Unwanted absorption mechanisms in the MIR band are removed or reduced so that the glass formulation exhibits optical performance as close as possible to the theoretical limit of a tellurium oxide glass. The glass formulation only includes glass constituents that provide the intermediate, modifiers and any halides (for OH— reduction) whose inherent absorption wavelength is longer than that of Tellurium (IV) oxide. The glass formulation is substantially free of Sodium Oxide and any other passive glass constituent including hydroxyl whose inherent absorption wavelength is shorter than that of Tellurium (IV) oxide. The glass formulation preferably includes only a small residual amount of halide.

Abstract: The invention relates to an optical fiber having an axial direction and a cross section perpendicular to said axial direction, and a method and preform for producing such an optical fiber. The optical fiber is adapted to guide light at a wavelength ?, and comprises a core region, an inner cladding region surrounding said core region, and at least one of a first type of feature comprising a void and a surrounding first silica material. The core, the inner cladding region and the first type of feature extends along said axial direction over at least a part of the length of the optical fiber. The first silica material has a first chlorine concentration of about 300 ppm or less.

Abstract: The invention relates to a method for producing an infrared transmitting fiber (50) comprising the steps of providing a preform (20) of the infrared transmitting fiber (50) to be produced, said preform (20) comprising a receptacle, which is the precursor of the fiber's cladding, and a solid solution provided inside said receptacle, said solid solution being the precursor of the fiber's core; heating the fiber's preform (20) up to a temperature in which the receptacle softens and the solid solution melts; collecting the flow generated by the softened receptacle; drawing the fiber (50) from the collected flow.

Abstract: A method of manufacturing an optical fiber preform, the method comprising: providing a substantially elongated core preform made out of a core fluorinated glass; providing a substantially elongated and substantially tubular cladding preform made out of a cladding fluorinated glass, the cladding preform defining a bore extending substantially longitudinally therethrough; inserting the core preform into the bore of the cladding preform; fusing the core preform and the cladding preform to each other to produce an intermediate preform; heating the intermediate preform up to a stretching temperature, the stretching temperature being such that the core and cladding fluorinated glasses both have a viscosity of between 10?7 and 10?9 Pa s at the stretching temperature; stretching the intermediate preform at the stretching temperature to produce a stretched intermediate preform; and cutting a section of the stretched intermediate preform.

Abstract: A method for fabricating a porous silica preform includes the steps of supplying fuel gas for generating an oxyhydrogen flame to a glass synthesizing burner; supplying Gas A containing silicon and Gas B containing fluorine to the burner; synthesizing glass particles; and depositing the glass particles around a starting rod, in which when glass particles are deposited directly on the starting rod, a supply of Gas A and a supply of Gas B supplied to the burner are adjusted so that a ratio of the number of fluorine atoms to the number of silicon atoms in the gas supplied to the burner satisfies the following Formula (1): {(number of F atoms)/(number of Si atoms)}?0.

Abstract: A tellurite glass composition doped with a first lanthanide, preferably Tm, and codoped with another lanthanide oxide, e.g. Ho, is provided. The glass includes 4-12 mole % of alkalihalide XY, X being selected from the group of Li, Na, K, Rb, Cs and Fr and Y being selected from the group of F, Cl, Br and I. A preferred glass contains about 10 mole % of the alkalihalide CsCl. The addition of alkalihalide XY results in an enhanced energy transfer from the first to the second lanthanide ion, whereby the lower energy level of the first lanthanide ion is depopulated. The ratio between upper and lower energy level lifetimes for the first lanthanide ion can be reduced to a value below one, enabling efficient amplifier fibers.

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: An optical waveguide comprising cladding 1 and core segment 20 buried in cladding 1 and serving as a waveguide, wherein a combination of glass material constituting the core segment 20 and another glass material constituting the cladding 1 is so selected that an absolute value of difference in coefficient of thermal expansion between these materials (?1-?2) is within a range of 0 and 9×10?7° C., where ?1 denotes a coefficient of thermal expansion of the former material and ?2 denotes that of the latter material.

Abstract: A starting material for producing optical fibers contains metal halides. The refractive index of the optical fiber formed from the starting material is predeterminable by adjusting a partial pressure ratio of a halogen-containing gas mixture. The starting material is produced by mixing halogenated gases into a gas mixture with the desired partial pressure ratio, causing a chemical reaction at a first temperature of the gas mixture with at least metal to form a reaction product, the first temperature being higher than the melting temperature of the reaction product and cooling the reaction product to a second temperature that is below the melting temperature.

Abstract: The invention provides a monomode optical fiber and a monomode preform (2) having a mother preform (22) housed in an outer sleeve tube (20). It is characterized in that it also includes an intermediate tube (21) between the mother preform (22) and the outer tube (20), the intermediate tube (21) possessing viscosity at fiber-drawing temperature which is less than the viscosity(ies) at fiber-drawing temperature of the mother preform (22) and of the outer tube (20). The invention also provides a method of manufacturing a monomode optical fiber. The fiber has a core that is better centered and less deformed than in the prior art. An application of the invention lies in making an optical amplifier.

Abstract: A method and apparatus are disclosed for the manufacture of an optical fiber preform having incorporated therein a comparatively high concentration of rare earth dopant material, and which thus can be drawn and processed into an optical fiber having low numerical aperture, low core attenuation, and high pumping power absorption. The high concentrations of rare earth dopant material are accomplished through either the “hybrid vapor processing” (HVP) method or a “hybrid liquid processing” (HLP) method, each capable of being practiced in combination or independently of one another. The HVP method involves the vaporization of a rare earth halogen by the exposure thereof to a sufficiently elevated temperature, independently, or contemporaneously with the transport of the resultant rare earth halogen laden vapor, into a glass forming oxidation reaction zone on a flowing stream of essentially an unreactive inert gas, such as helium.

Abstract: A starting material for producing optical fibers contains metal halides. The refractive index of the optical fiber formed from the starting marterial is predeterminable by adjusting a composite of the molten bath. The starting material is produced by mixing halogenated gases into a gas mixture with the desired partial pressure ratio, causing a chemical reaction at a first temperature of the gas mixture with at least metal to form a reaction product, the first temperature being higher than the melting temperature of the reaction product and cooling the reaction product to a second temperature that is below the melting temperature.

Abstract: A method and apparatus are disclosed for the manufacture of an optical fiber preform having incorporated therein a comparatively high concentration of rare earth dopant material, and which thus can be drawn and processed into an optical fiber having low numerical aperture, low core attenuation, and high pumping power absorption. The high concentrations of rare earth dopant material are accomplished through either the “hybrid vapor processing” (HVP) method or a “hybrid liquid processing” (HLP) method, each capable of being practiced in combination or independently of one another. The HVP method involves the vaporization of a rare earth halogen by the exposure thereof to a sufficiently elevated temperature, independently, or contemporaneously with the transport of the resultant rare earth halogen laden vapor, into a glass forming oxidation reaction zone on a flowing stream of essentially an unreactive inert gas, such as helium.

Abstract: A method and apparatus are disclosed for the manufacture of an optical fiber preform having incorporated therein a comparatively high concentration of rare earth dopant material, and which thus can be drawn and processed into an optical fiber having low numerical aperture, low core attenuation, and high pumping power absorption. The high concentrations of rare earth dopant material are accomplished through either the “hybrid vapor processing” (HVP) method or a “hybrid liquid processing” (HLP) method, each capable of being practiced in combination or independently of one another. The HVP method involves the vaporization of a rare earth halogen by the exposure thereof to a sufficiently elevated temperature, independently, or contemporaneously with the transport of the resultant rare earth halogen laden vapor, into a glass forming oxidation reaction zone on a flowing stream of essentially an unreactive inert gas, such as helium.

Abstract: The invention provides a monomode preform (2) comprising a mother preform (22) housed in an outer sleeve tube (20). It is characterized in that it also includes an intermediate tube (21) between the mother preform (22) and said outer tube (20), the intermediate tube (21) possessing viscosity at fiber-drawing temperature which is less than the viscosity(ies) at fiber-drawing temperature of said mother preform (22) and of said outer tube (20). The invention also provides a method of manufacturing a monomode optical fiber. The fiber has a core that is better centered and less deformed than in the prior art. An application of the invention lies in making an optical amplifier.

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

Abstract: A method and apparatus is disclosed for the manufacture of an optical fiber preform having incorporated therein a comparatively high concentration of rare earth dopant material, and which thus can be drawn and processed into an optical fiber having low numerical aperture, low core attenuation, and high pumping power absorption. The high concentrations of rare earth dopant material are accomplished through either the “hybrid vapor processing” (HVP) method or a “hybrid liquid processing” (HLP) method, each capable of being practiced in combination or independently of one another. The HVP method involves the vaporization of a rare earth halogen by the exposure thereof to a sufficiently elevated temperature, independently, or contemporaneously with the transport of the resultant rare earth halogen laden vapor, into a glass forming oxidation reaction zone on a flowing stream of essentially an unreactive inert gas, such as helium.

Abstract: A method for the manufacture of optical components, at least one three-dimensional optical waveguide structure being produced in a light-sensitive substrate by locally subjecting the substrate to an exposure so that a difference in refractive index between the substrate and the at least one optical waveguide structure is created. Provision is made for an exposure to occur at least twice, at different angles of incidence for the light perpendicular to a light wave propagation direction of the optical waveguide structure; the substrate surrounding what will later be the optical waveguide structure thereby experiences a diminution in refractive index, the optical waveguide structure being defined using a mask.

Abstract: A glass 1 is irradiated with a focused pulsed laser beam 2 having a peak power density of 10.sup.5 W/cm.sup.2 or more and a repetition rate of 10 KHz or more. The glass 1 irradiated with the laser beam 2 changes its refractive index at the focal point 4. During the laser beam irradiation, the glass 1 is continuously moved with respect to the focal point of the pulsed laser beam 2 or continuously scanned with the focused laser beam 2, so as to form the refractive index changed region (i.e. an optical waveguide 5) with a predetermined pattern. The glass 1 in which the optical waveguide 5 will be formed may be any kind of glass having high transparency.

Abstract: In an induction furnace for the synthesis of glasses, in particular fluorozirconate glasses for optical fibres for telecommunications, the support device (6') for the crucible (3) is associated with a pair of sleeves (7, 9) between which an annular element (8) which constitutes the actual support element is inserted. The first sleeve (7) has such longitudinal dimensions that the crucible (3) is supported in the annular element (8) in such a way as to be spaced from the planar element (5'), and the second sleeve has such longitudinal dimensions that its top edge is at a level higher than that of the top edge of the crucible (3), to obtain a homogeneous temperature region extending at least along the entire height of the crucible (3).

Abstract: A glass is irradiated with a focused pulsed laser beam having a peak power density of 10.sup.5 W/cm.sup.2 or more and a repetition rate of 10 KHz or more. The glass irradiated with the laser beam changes its refractive index at the focal point. During the laser beam irradiation, the glass is continuously moved with respect to the focal point of the pulsed laser beam or continuously scanned with the focused laser beam, so as to form the refractive index changed region (i.e. an optical waveguide) with a predetermined pattern. The glass in which the optical waveguide is formed may be any kind of glass having high transparency.

Abstract: A furnace body for a glass preform elongating apparatus which makes an elongated body by passing the glass preform through the furnace body and elongating the glass preform while heating the glass preform, the furnace body comprising a furnace core tube shaped like a cylinder through which the glass preform passes and having so adequate length in an axial direction that the elongated body may not bend or distort its form, a heating member disposed at an outer peripheral portion of the furnace core tube, a thermal insulator enveloping the furnace core tube and the heating member from outside in circumferential and axial directions thereof, and a furnace body outer shell holding the thermal insulator therein, wherein a through hole is disposed near the heating member downstream thereof in an advancing direction of the glass preform so as to penetrate through the furnace core tube, thermal insulator, and furnace body outer shell in the direction orthogonal to the furnace core tube.

Abstract: A process for producing a thin film of a fluoride comprising reacting a gaseous fluorinating agent and gas of a volatile organometallic compound in a gas phase in a reactor, wherein a plasma of the gaseous fluorinating agent obtained by activating the gaseous fluorinating agent by microwave under a condition of electron cyclotron resonance is used as a fluorine source, and the fluoride is deposited on a substrate by reacting the plasma of the gaseous fluorinating agent with the gas of a volatile organometallic compound at outside of an area of generation of the plasma. A thin film of a fluoride which contains very little impurities such as carbon, oxygen, and organic substances, and is highly pure, transparent, and consolidated is produced.

Abstract: The specification describes a method for the manufacture of fluoride glass optical fibers which are covered with a protective coating of phosphate glass. The coating is produced by dipping the fluoride glass preform in a phosphate glass melt prior to drawing the optical fiber. The fluoride glass is ZBLAN. The phosphate glass has a glass transition temperature below 200.degree. C., which allows the dipping step to be carried out at a relatively low temperature where the preform temperature is maintained well below the crystallization temperature of the fluoride glass, and also where the viscosity of the fluoride glass preform is substantially higher than the viscosity of the phosphate glass coating material.

Abstract: A method of making core holes in cast cladding glass for fabricating optical fiber preforms to make single and multimode optical fibers. Liquid cladding glass is pored into a casting mold having a metallic wire that is translated through the liquid glass as it cools so that the wire essentially carves out a smooth cylindrical core hole along the cylindrical axis of the cooled cladding glass. The method substantially reduces surface contamination at the interface of the core hole and the cladding glass because any liquid glass that comes in contacts with the metallic wire is removed during the process, leaving behind a pristine glass surface.

Abstract: A method of fabricating a fluoride glass optical fiber preform which has a fluoride glass core surrounded by a fluoride glass optical cladding includes the following steps: introducing the cladding glass in the molten state into a bottom part of a mold having a cylindrical inside cross-section, introducing the core glass in the molten state into a top part of the mold above the cladding glass, and inwardly solidifying the core glass and the cladding glass from the interface between the glasses and the mold. The kinetics of solidification of the core glass are such that complete solidification of the cladding glass occurs before complete solidification of the core glass.

Abstract: A method of fabricating optical preforms that yield optical fibers having minimal scattering centers by substantially eliminating bubbles and crystallites that form during preform fabrication. The method utilizes glasses having low viscosity in their liquid state to eliminate large bubbles that contain ambient gasses. Small bubbles that have sizes comparable to the wavelength of light are eliminated by simultaneously vacuum-pumping and slow-cooling the liquid glass used to fabricate the preform before pouring the glass into the preform cast mold. Finally, bubbles due to the formation of vacuums in the preform are eliminated by applying a temperature gradient across the cast mold to induce a steep vertical gradient in viscosity in the liquid glass when the liquid glass is poured in the mold.

Abstract: A process for producing fluoride glass, including the steps of: introducing a raw material for fluoride glass into a heating vessel; and heating the raw material in the heating vessel, while causing the heating vessel to have a negative internal pressure and introducing an inert gas into the heating vessel, thereby to melt the raw material under heating.

Abstract: A method of making a polyimide coated heavy metal fluorinated fiber includes the steps of drawing an optical fiber through a low-temperature curing polyimide solution to form a polyimide coating which cures in a range of about 200.degree. and 390.degree. C. A low curing temperature enables a low temperature profile to be used for curing the coating. The low-temperature curing conditions provide a maximum fiber exposure temperature above the glass transition temperature of the fiber but minimize crystallization of the fiber during curing. The method is also applicable to chalcogenide fibers which carry optical signals in the infrared region.

Abstract: Fluoride glass optical fibers are fabricated by minimizing the number of high-temperature operations. A tube comprising an external layer of a first fluoride glass of composition suitable to form the cladding of the fiber and an internal layer of a second fluoride glass of composition suitable to form the core of the fiber is prepared by a conventional rotational casting technique. Then, the internal layer is thinned by means of chemical etching at ambient temperature until the attainment of a ratio between the volumes of the two layers that corresponds to the ratio between the core and cladding diameters required for a single mode fiber, and the resulting tube is drawn.

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

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

Abstract: Method of manufacturing a multi-component glass cylindrical part comprising the operations of providing a vertical cylindrical cavity lined with porous membranes whose inside dimensions are very slightly larger than those of the glass cylindrical part and in which can slide a cylindrical pedestal, providing a seed mass of the glass on the pedestal, heating the seed mass until it melts, injecting a gas continuously into the porous membranes to form and maintain a layer of gas between the porous membranes and the molten seed mass preventing any contact between the molten seed mass and the porous membranes, feeding the molten seed mass from the top of the cavity by continuously dispensing a powder made up of the components of the glass, varying the composition of the powder as the cylindrical part is formed, so that the glass cylindrical part has a composition that varies in the longitudinal direction, and lowering the pedestal as the cylindrical part is formed.

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

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

Abstract: A method of making a polyimide coated heavy metal fluorinated fiber includes the steps of drawing an optical fiber through a low-temperature curing polyimide solution to form a polyimide coating which cures in a range of about 200.degree. and 390.degree. C. A low curing temperature enables a low temperature profile to be used for curing the coating. The low-temperature curing conditions provide a maximum fiber exposure temperature above the glass transition temperature of the fiber but minimize crystallization of the fiber during curing. The method is also applicable to chalcogenide fibers which carry optical signals in the infrared region.

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

Abstract: A deposition method for vapor deposition of a film of fluorine-containing glass on a substrate in which said substrate is put into contact with fluxs of the vapors of the various constituents of said glass, wherein said vapor fluxs are emitted simultaneously from at least two crucibles, a first crucible containing a host bath and main metal fluorides that constitute said fluorine-containing glass, and at least one second crucible containing dopants constituted by at least one rare earth halide.

Abstract: Halide glass articles, e.g. rods, tubes and preforms for making fluoride glass fibres, are prepared by melting and/or casting the articles under a low pressure, e.g. 0.01 to 500 mbars and, during the low pressure regime, a gas flow rate of between 0.01 to 100 liters/min (measured at NTP) is maintained. It has been found that subjecting the melts to a low pressure reduces the attenuation of the fibre which eventually results from the melts.

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

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

Abstract: The present invention relates to a process for the synthesis of fluoride glass by the sol-gel method.The object of the invention is to synthesize an impurity-free fluoride glass.This object is achieved with the aid of a process having stages consisting of preparing a wet oxygenated gel from precursors containing all the cations constituting said fluoride glass, hydrolyzing said gel, drying said gel and in which the process is characterized in that it also comprises the stage consisting of treating said oxygenated gel by a fluorinating agent in the vapour phase, at a temperature below the glass crystallization point.This process more particularly makes it possible to produce fluoride glass for optical fibres.

Abstract: Halide glass articles, e.g. rods, tubes and preforms for making fluoride glass fibres, are prepared by melting and/or casting the articles under a low pressure, e.g. 0.01 to 500 mbars and, during the low pressure regime, a gas flow rate of between 0.01 to 100 liters/min (measured at NTP) is maintained. It has been found that subjecting the melts to a low pressure reduces the attenuation of the fibre which eventually results from the melts.

Abstract: A new method for preparing low loss multimode and monomode glass optical fibers which avoids casting or pouring the core and clad melts is disclosed. The new technique is based on a reactive-gas-transport approach which avoids contamination from absorbing impurities and scattering centers by reacting the glass melt with reactive gases which remove impurities and increase the refractive index of the fiber.