Abstract: A heating furnace for heating a porous preform made of fine particles of quartz base glass for an optical fiber in an atmosphere comprising a fluorine-containing atmosphere to add fluorine to the preform and to vitrify the preform to produce a glass preform for an optical fiber, which comprises a heater and a muffle tube positioned inside the heater to separate a heating atmosphere from the heater, wherein at least the inner layer of the muffle tube consists of highly pure carbon.

Abstract: A fluorine-doped silica soot cylinder (11) is consolidated by containing it within an encapsulation structure (29) within a furnace (21). The atmosphere within the encapsulation structure is kept substantially stagnant during the consolidating, and the volume enclosed by the encapsulation structure (29) is only slightly greater than the volume of the soot cylinder (11). A gap (52) between the volume enclosed by the encapsulating structure and the furnace is kept small enough to impede gas flow to a sufficient extent that the atmosphere within the encapsulating structure (29) is substantially stagnant during consolidation. During consolidation, fluorine concentration within the encapsulation structure (29) is uniformly distributed within the soot cylinder (11).

Abstract: A new, simplified method of fabricating optically transparent fluoride glasses containing ZrF.sub.4 and/or HfF.sub.4 has been developed which relies on a high vacuum pretreatment for surface dehydration, melting in a rigorously inert argon atmosphere, and incorporation of a nonvolatile metallic oxidant in the melt such as InF.sub.3 or SnF.sub.4. Previous methods for making these glasses have relied on either addition of ammonium bifluoride into the batch materials, or melting in an oxidizing atmosphere (so-called reactive atmosphere processing or RAP); both of these latter techniques have significant drawbacks.

Abstract: The present invention is directed to a method for synthesizing fluorine-containing, aluminosilicate crystals having a stoichiometry approximating that of topaz. The method comprises three basic steps:(1) vapors of a readily-oxidizable compound of silicon and of a readily-oxidizable compound of aluminum and fluorine are passed to a flame oxidation burner;(2) amorphous fluorine-containing, aluminosilicate particles resulting from the combustion of those gases are collected; and(3) the collected particles are sintered into an integral body at a temperature between about 650.degree.-925.degree. C.

Abstract: Integrated optical guides are fabricated on fluoride glass plates by expog such plates to an atmosphere of a gaseous halogen other than fluorine, or of a compound capable of generating such a halogen, at high temperature and pressure, so as to obtain a ion exchange between fluoride ions in the glass and halide ions.

Abstract: A halide glass core fiber is clad by providing two melts that selectively join to form the molten clad fiber in a temperature range from 580.degree. C. to 600.degree. C. A separate heating means controls the fiber melt at the die nozzle. Because of the low viscosity and the narrow proto congelation temperature zone, the clad fiber is extruded and drawn in the vertical direction counter the effect of gravity.

Abstract: A novel solution of H.sub.3 BO.sub.3 dissolved in strong hydrochloric or nitric acid is used to etch fluoride glass preforms used to manufacture fluoride glass fibers. Because of the excellent cleaning ability of the present solution, as well as the absence of sub-micron deposits, the resulting fibers have excellent bending strength.

Abstract: A double crucible fiberizing apparatus and process for producing a continuous glass filament having a core fluoride-containing glass concentrically surrounded by a clad fluoride-containing glass at increased throughput speeds while simultaneously achieving increased length and uniform filament diameter are disclosed.

Abstract: A new method for fabricating devices which include multicomponent metal halide glasses, e.g., multicomponent metal halide glass optical fibers, is disclosed. In accordance with the inventive method, a multicomponent metal halide glass body, essentially free of crystallites, is produced by cooling essentially every portion of a melt incorporated into the glass body at a quench rate which is necessarily greater than or equal to about 10 Kelvins per second (K/sec). This necessary quench rate is achieved by successively quenching relatively small portions of the melt, e.g., thin layers or droplets of melt material, having relatively small cross-sectional dimensions.

Abstract: A method for producing a glass preform for an optical fiber comprising a core and a cladding containing fluorine is fisclosed. The method comprises forming a porous glass layer of substantially pure quartz on an outer surface of a fused glass rod consisting of a central portion of substantially pure quartz and a peripheral portion of quartz glass containing fluorine, and heating a composite of the fused glass rod and the porous glass layer in an atmosphere containing fluorine to add fluorine to the porous glass layer and to make it transparent, by which contamination of glass with hydroxyl groups can be prevented and light transmission characteristics of an optical fiber fabricated from the glass preform are improved.

Abstract: An improved method of rapidly forming halide glass wherein the heating and cooling schedule has two phases of heating and cooling. This improved method substantially limits the loss of volatile components because of the significantly shortened interval of time at the elevated melting temperatures. The average time under heating is about 80 minutes. Cooling is as rapid as possible. The homogenization occurs above 800.degree. C. for about 20 minutes.

Abstract: A process for the production of a glass by the vacuum melting method using silica as a raw material is disclosed, comprising filing a silica fine powder in a suitable vessel, heating it in the presence of an accelerator for phase conversion to obtain a porous formed body consisting of a cristobalite phase, and then heating and melting the formed body in vacuo. According to the present invention, a transparent and active glass having a high quality can be produced at an inexpensive cost.

Abstract: There is disclosed herein a method of making a glass substrate coated with an adherent, doped, tin oxide coating and article produced thereby. The glass substrate is heated to a spraying temperature which is sufficiently hot so that a heat decomposable, tin-containing material coming into the vicinity of the glass substrate will be heat decomposed permitting the tin contained in the tin-containing material to be oxidized and deposited as a doped tin oxide. The tin-containing material is applied in an oxygen ambient and is a material which contains both dibutyltin dibutoxide and trifluoroacetic acid. The preferred heating and application steps are undertaken under conditions that the spraying temperature and the ratio of milliliters of dibutyltin dibutoxide to milliliters of trifluoroacetic acid contained in the tin-containing material fall at some point located on or within the island area designated by the letter A in the map of these variables as set forth in FIG. 1 of the drawings.

Abstract: Planar single-mode optical waveguides which can conduct light with defined polarisation have so far been embedded in, for example, a cladding made from crystalline LiNbO.sub.3. The crystalline structure of the cladding produces disadvantageous properties such as the fact that the birefringence depends on the geometric profile of the guide, relatively high optical loss, poor fibre coupling, birefringence rigidly fixed by material constants, and a costly manufacturing process. The new process results in an optical waveguide in which both the cladding and the actual guide itself are made of glass with a certain composition, thereby avoiding the disadvantages stated. With the help of a non-isothermal plasma CVD process a light-guiding core region (1) is surrounded on a substrate (4) by cladding layers (2, 2') and a cladding region (3, 3'), the thermal coefficient of longitudinal expansion of the cladding region (3, 3') differing markedly from that of the two homogeneous cladding layers (2, 2').

Abstract: A method for producing a glass preform for use in the fabrication of an optical fiber which comprises inserting a core rod made of quartz glass in a cladding tube made of quartz glass added with fluorine, heating them from the outside of the cladding tube to fuse them together to form a primary glass preform comprising a core rod and a first cladding layer around the core rod, depositing SiO.sub.2 soot particles around the primary glass preform and thermally treating the soot deposited glass preform in the presence of a fluorine-containing compound to form a final glass preform from which an optical fiber is fabricated. From the glass preform produced by this method, an optical fiber having low attenuation of light transmission in a wide range of wave-length is fabricated.

Abstract: An improved method of making carbon dioxide and chlorine free fluoride-based glass wherein the atmosphere in the furnace enclosure is sulphur hexafluoride gas at a positive over pressure.

Abstract: Incorporation of fluorine into a porous silica body, such as an unsintered body produced by a sol-gel method, by VAD or OVPO, reduces or eliminates bubble or pore formation upon re-heating of the glass formed by sintering of the porous material. Effective fluorine concentrations are between 0.01 and 5% by weight. The invention can be used advantageously in producing preforms and optical fiber.

Abstract: A glass preform for use in the fabrication of a dispersion shifted single mode optical fiber is produced by a method for comprising steps of inserting a core member consisting of an inner core part made of a germanium-added quartz glass which optionally contains fluorine and an outer core part made of a quartz glass having a refractive index smaller than that of the inner core part in a glass tube made of a fluorine-added quartz glass having a refractive index smaller than that of the outer core part, heating the core member and the glass tube to collapse the glass tube and fuse them together to produce a glass perform. The glass preform comprises a core member consisting of an inner core part made of GeO.sub.2 -SiO.sub.2 glass or GeO.sub.2 -F-SiO.sub.2 glass and an outer core part made of F-SiO.sub.2 glass and a cladding made of F-SiO.sub.2 glass and provides a dispersion shifted single mode optical fiber having reduced attenuation of light transmission in the 1.5 .mu.m wavelength band.

Abstract: Alkali silicate glasses, pigmented with Co.sup.2+ or with Co.sup.2+ and Ni.sup.2+, and having the composition:SiO.sub.2 : 52-71% by weightPbO: 2.9-16.8% by weightSnO.sub.2 : 0.1-1.65% by weightNa.sub.2 O: 6.7-16.7% by weightK.sub.2 O: 0.5-9.9% by weightNa.sub.2 O+K.sub.2 O: 13.3-18.3% by weightNiO+CoO: 0.1-4.4% by weightAs.sub.2 O.sub.3 +Sb.sub.2 O.sub.3 : 0.05-0.5% by weight.SIGMA.RO: 0-8.6% by weightB.sub.2 O.sub.3 : 0-8.5% by weightAl.sub.2 O.sub.3 : 0-0.55% by weightZnO: 0-10.5% by weight,in which R is Mg, Ca, Sr, Ba or a combination thereof, are disclosed. The alkali silicate glasses of the invention are useful as optical filter glasses.

Abstract: A method for producing a glass preform for optical fibers in which fluorine is efficiently incorporated into the preform without incorporation of Fe or Cu. A fine glass particle mass, made primarily of quartz, is converted into transparent glass by heating it in a gas atmosphere containing at least a fluorine-based compound gas and a chlorine-based compound gas. The preferred heating range is 1,100.degree. to 1,400.degree. C.

Abstract: A quartz optical fiber comprising a core having a higher refractive index and made of pure quartz containing fluorine and phosphorus pentoxide and a cladding having a lower refractive index, a weight ratio of fluorine and phosphorus pentoxide in the core being larger than 1 (one), which is substantially free from unstability of the glass structure.

Abstract: While collapsing the central duct in hollow glass optical fiber preforms, an etchant consisting of a mixture of oxygen and a fluorocarbon compound from the group C.sub.2 F.sub.6, C.sub.3 F.sub.8 and N-C.sub.4 F.sub.10 is passed through the duct. In particular, the etchant is passed through the duct only when the duct's diameter is 1 mm or smaller. The resulting solid preforms and optical fibers drawn therefrom do not have a central dip in the refractive index profile.

Abstract: A rod-in-tube method for producing a glass preform for use in the fabrication of an optical fiber, which comprises steps of inserting a glass rod constituting a core material in a glass tube constituting a cladding material, heating the rod-tube composite by an outer heating source with introducing, in the gap between the rod and the tube, a gaseous mixture containing a silicon halogenide, a fluorine-containing compound and oxygen gas in which a ratio of silicon and fluorine (Si/F) is larger than 1/300 and smaller than 1/5, and heating and fusing the composite at a temperature not lower than 1,900.degree. C. with filling the gap by a gaseous mixture comprising a halogen-containing compound and oxygen gas; from which glass preform, an optical fiber with low attenuation of light transmission, particularly in a long wavelength range, is fabricated.

Abstract: Optical waveguide having a fused silica core and a fluorine doped silica cladding is made by heating a cylinder of silica in fluorine, the cylinder initially having an outer annular particulate or porous region which is dried by the fluorine and into which fluorine diffuses to lower the refractive index of the silica when fused. The cylinder is made by depositing particulate silica onto a mandrel, drying the silica in chlorine, and heating the silica to densify it. Further particulate silica is deposited and is then heated in a fluorine-containing gas to dry, fluorine diffuse, and sinter the porous outer part of the silica. The resulting tubular silica preform is heated to collapse the tubular preform into a rod from which optical waveguide is drawn, the waveguide having a fluorine doped silica cladding.

Abstract: The disclosed simple, economical and rapid sol-gel process for forming a silica-based glass body, termed the "vapogel" process, comprises introduction of a silicon halide-containing gas (e.g., SiCl.sub.4 +O.sub.2) into an aqueous medium. The thus formed sol can gel within minutes, resulting in a monolithic gel from which particles having a narrow size distribution can easily be formed. The thus formed particles can be used to produce a glass body such as an optical fiber. Various techniques for forming the glass body from the gel are disclosed. Among the many advantages of the vapogel method are its ability to produce very homogeneous mixed oxide glasses of composition not obtainable by prior art sol-gel processes, and the advantageous mechanical properties of the gel produced by the method. The latter makes possible, inter alia, formation of particles having a relatively narrow size distribution.

Abstract: A process for treating a halide, e.g. fluoride, glass composition, characterized by contacting a melt of the composition with dry oxygen. Oxygen, simply on contact with a fluoride glass melt, converts transition metals, e.g. from Fe(II) to Fe(III), from one stable state to another and thereby reduces loss at transmission wavelengths in optical fiber, e.g. the loss at 2.7 .mu.m attributable to Fe(II).

Abstract: In an inside tube vapor phase deposition process for the production of doped silica glass by an oxidation reaction for optical fibre manufacture, in particular fluorine doped silica, the oxidation reaction is prevented from occurring until the reactant material, for example silicon tetrachloride and a fluorinating reagent, has been heated to a temperature above that required for the oxidation reaction. This preheating of the reactant material results in the oxidation reaction producing compositions of glasses which are not allowed from thermodynamic considerations at the lower temperature usually employed for the oxidation reaction, for example silica more highly doped with fluorine than hitherto achieved.

Abstract: Optical waveguide having a fused silica core and a fluorine doped fused silica cladding is made by depositing particulate core silica onto a support tube and then drying and densifying the silica. Further particulate cladding silica is deposited and is heated in a fluorine containing gas to effect drying, fluorine diffusion into and sintering the cladding silica. The support tube is etched away and the resulting tubular preform is heated to collapse it into a rod from which waveguide is drawn, the waveguide having a fluorine doped silica cladding.

Abstract: A method and apparatus is disclosed which ensures highly accurate control of the core-cladding diameter, enabling the fabrication of a preform for the single mode fiber. Moreover, glass refining steps for dehydration, the removal of compound ions, the reduction of the absorption loss by transition metals, etc. and preform manufacturing steps are combined into a series of steps, and the entire manufacturing process can be mechanized and automatically controlled; therefore, the yield rate of product is high and the industrial-scale productivity is also excellent.

Abstract: The process employs solid-state halides heated at high temperature, under pressure conditions necessary to their vaporization, and obtains their condensation to a solid state on the internal surface of a glass tube, which, after collapsing, forms the preform.

Abstract: A vapor phase method for making a metal halide material useful for the manufacture of an infrared transmitting optical waveguide fiber or other optical device, and the use of the method for making such a device, wherein a halogenated beta-diketonate of a metal to be incorporated in the device is converted to the corresponding metal halide by controlled decomposition of the halogenated diketonate, are described.

Abstract: The process for manufacturing halide glasses uses a reaction between organometallic and inter-halide or halide-derived compounds, started at a temperature ranging from the highest melting temperature and the lowest boiling temperature of the compounds used.

Abstract: Incorporation of fluorine into a porous silica body, such as an unsintered body produced by a sol-gel method, by VAD or OVPO, reduces or eliminates bubble or pore formation upon re-heating of the glass formed by sintering of the porous material. Effective fluorine concentrations are between 0.01 and 5% by weight. The invention can be used advantageously in producing preforms and optical fiber.

Abstract: A method of and arrangements for manufacturing glass bodies, in which method a thixotropic suspension, being the starting material for the glass body, is used to form a porous green body which is subsequently subjected to a purification step in a heated gaseous phase and then sintered to form a glass body, the starting material being homogenized and liquefied in a closed elastic mould by subjecting it to sound or ultrasonic, after which the liquid starting material is given the shape of the glass body to be formed and then solidified.

Abstract: An optical fiber comprising a core essentially made of quartz and a cladding made of fluorine added quartz is fabricated with good productivity from a glass preform produced by a method comprising maintaining a hollow cylindrical porous glass preform in a first high temperature atmosphere comprising at least one fluorine-containing compound with jetting a cooling gas through the central hollow part of the porous glass preform to grade the amount of fluorine to be added in the radial direction of the porous glass preform and then sintering the porous glass preform in a second high temperature atmosphere kept at a temperature higher than the first high temperature atmosphere to make it transparent.

Abstract: A method of and arrangements for manufacturing glass bodies, in which the starting material for the glass body, being a suspension having a microdispersed solids content, is used to form a porous green body which is subsequently purified and sintered, in which, by separating the phases of the suspension in an arrangement in which a pressure difference can be built up, the green body is deposited on a porous membrane whose shape corresponds to that of the glass body to be produced, the pores of the membrane having a diameter in the range from 1 to 500 times the average particle diameter of the solids content of the suspension.

Abstract: The present invention relates to a method of producing a fluoride glass preform and/or fiber having a modified refractive index by heating the fluoride glass preform to a temperature that is above its glass transition temperature, but below its devitrification temperature; inserting a first electrode into the inner core of the preform and surrounding the outer perimeter of the preform with a second electrode of opposite polarity; means for generating an electromotive force; and applying an electromotive force through the first electrode and the second electrode which causes a movement of positive ions toward the electrode of opposite charge while simultaneously causing a movement of negative ions toward its electrode of opposite charge such that the movement of these ions results in a modification of the refractive index of the preform.

Abstract: A method for producing a glass preform for a single mode optical fiber comprising a core and a cladding, which method comprises depositing fine glass particle of a glass raw material on a periphery of a cylindrical seed member having a smooth and clean outer surface by flame hydrolysis to form a soot of the fine glass material, pulling out the seed member from the soot, inserting a core glass rod in a hollow portion of the soot and dehydrating and sintering a complex of a core rod and a cladding to produce a glass preform from which a single mode optical fiber having low attenuation of light transmission, particularly due to absorption by hydroxyl groups can be drawn.

Abstract: A rod-in-tube method for producing a glass preform for use in the fabrication of an optical fiber, which comprises steps of inserting a glass rod as a core material in a glass tube as a cladding material, fusing and closing one end of the cladding material, filling a gap between the core and cladding materials with an atmosphere containing at least one gaseous halogen-containing compound and then heating the core and cladding materials at a temperature not lower than 1,900.degree. C. to collapse the gap between them and to fuse them together, from which glass preform, an optical fiber with low attenuation of light transmission is fabricated.

Abstract: Heavy metal fluoride glasses are made by a process that requires high purity fluoride constituent compounds, some of which are further refined by sublimation. Handling occurs in a protective atmosphere such as argon. The charge is placed in a sealed modified optical growth furnace having the ability of atmosphere control, heat control and position control of the charge. The charge is firstly raised to its fusion temperature, then to an admixture temperature, and finally to a higher temperature. The charge is immediately removed from the heating source and quickly cooled through the critical crystallization region. The total heating and cooling time being about one to two hours. The resulting glass ingot is partially annealed. The HMFG of (Zr or Hf)F.sub.4 -BaF.sub.2 -LaF.sub.3 -AlF.sub.2 consistently exhibits low levels of both light scattering and bulk OH contact, along with very reproducible hardness, thermal parameters, and UV and IR edge absorption behavior.

Abstract: A process for manufacturing optical fibers and components from bars or molds of fluoride glass draws out optical quality molds from highly pure glass. The glass is stretched or fibered into optical fibers in a dry atmosphere free of dust, organic, metallic or mineral vapors. The process leads to a low hydroxyl content fluoride glass which is used in the manufacture of optical fibers and components. The dehydration of the fluoride mixture occurs during the steps of prolonged heating at under 450.degree. C. in the presence of fluoride or ammoniumbifluoride, and of holding the molten mixture at a high temperature until dehydration occurs. The drawing out, stretching, and fibering are carried out in a vacuum.

Abstract: Process for treating molten mixtures of fluorozirconate glass to form high purity infrared transparent glass which is essentially free of zirconium fluoride disassociation impurities and anion impurities. The molten mixture or melt is treated with a moisture-free oxygen reactive atmosphere to prevent formation of disassociation impurities or to remove any of these impurities already present in the melt. The melt is also contacted simultaneously or subsequently with a fluorine species reactive gas to remove any oxygen anion impurities formed during the oxygen reactive atmosphere treatment of the melt to thereby provide a glass having complete fluorine stoichiometry and which is free of disassociation and anion impurities.

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

Abstract: The invention provides an efficient method for the dehydration, i.e. removal of silicon-bonded hydroxy groups, of a porous silica body before vitrification as a precursor of quartz glass-made optical fibers obtained by the flame hydrolysis of a silicon compound and deposition of fine silica particles formed therefrom. The problems and disadvantages accompanying the use of conventional dehydrating agents can be solved in the invention by heating the hydroxy-containing porous silica body at 1000.degree. to 1300.degree. C. in an atmosphere containing thionyl fluoride or sulfuryl fluoride as the dehydrating agent which is also effective as a dechlorinating agent so that the optical fibers prepared from the quartz glass material of the invention are highly transparent and resistant against hydrogen-containing atmosphere at elevated temperatures.

Abstract: A tubular porous silica preform is made by depositing particulate silica on a mandrel from which the preform is subsequently removed. A solid cylindrical porous silica preform is made by depositing particulate silica on an end surface of a support body. The porous preforms are then dried and the tubular preform is heated in a fluorine containing atmosphere to introduce a fluorine dopant into the silica. The rod preform is then placed inside the tubular preform and the two preforms are further dried in a chlorine atmosphere to remove residual moisture. The dual preforms are then heated in a zone sintering furnace to consolidate and collapse the porous material of the rod and tubular preforms into a transparent fused silica rod. The composite preform obtained is heated and dielectric optical waveguide drawn from it, the waveguide having a pure silica or doped silica core derived from the rod preform and a fluorine doped silica cladding derived from the tubular preform.

Abstract: A method for producing sodium-containing glasses, by a vapor deposition process wherein a vapor mixture containing a sodium fluoroalkoxide compound is reacted to provide a particulate sodium-containing vapor deposition product which can be sintered to a glass.

Abstract: Optical waveguide having a fused silica core and a fluorine doped silica cladding is made by heating a cylinder of silica in fluorine, the cylinder initially having an outer annular particulate or porous region which is dried by the fluorine and into which fluorine diffuses to lower the refractive index of the silica when fused. The cylinder is made by depositing particulate silica onto a mandrel, drying the silica in chlorine, and heating the silica to densify it. Further particulate silica is deposited and is then heated in a fluorine-containing gas to dry, fluorine diffuse, and sinter the porous outer part of the silica. The resulting tubular silica preform is heated to cause fusion of the porous silica and to collapse the tubular preform into a rod from which optical waveguide is drawn, the waveguide having a fluorine doped silica cladding. The fluorine drying and diffusion steps produce HF which is extremely corrosive.

Abstract: A method for removing a surface layer from a metal fluoride glass containing barium ions, particularly glass rods of the type used for manufacturing fibers for optical communications technology. A rapid, uniform and turbidity-free erosion of a disturbed outside layer of the starting glass is accomplished with an etchant solution in which a fluoride complexing agent or a barium complexing agent is dissolved. In particular, a rapid dissolving of a barium fluoro-zirconate glass is achievable with an etchant solution containing acidic Zr (IV) salts, whereby the risk of contaminating the so etched surface by the etchant solution does not exist.

Abstract: This invention relates to a method forming fluorine-doped glass. A coating of glass particles is deposited on the surface of a cylindrical rod of high purity glass. The coated rod is inserted into a furnace which contains a cylindrical muffle formed of high silica content glass. A fluorine-containing atmosphere is flowed through the muffle and over the outer surface of the coating of glass particles and also flows inwardly through the interstices thereof. The temperature within the furnace is sufficiently high to cause fluorine to diffuse into the surfaces of the glass particles and to cause the particles to fuse and form a fluorine-containing dense glass coating on the surface of the rod.

Abstract: The process of manufacturing optical fibers of extremely low loss in the medium infrared permits the fabrication of glass preforms having as basic materials metal-fluorides obtained from vapor-phase reactants.