Abstract: A doped silica-titania (“DST”) glass article that includes a glass article having a glass composition comprising a silica-titania base glass containing titania at 7 to 14 wt. % and a balance of silica, and a dopant selected from the group consisting of (a) F at 0.7 to 1.5 wt. %, (b) B2O3 at 1.5 to 5 wt. %, (c) OH at 1000 to 3000 ppm, and (d) B2O3 at 0.5 to 2.5 wt. % and OH at 100 to 1400 ppm. The glass article has an expansivity slope of less than about 1.3 ppb/K2 at 20° C. For DST glass articles doped with F or B2O3, the OH level can be held to less than 10 ppm, or less than 100 ppm, respectively. In many aspects, the DST glass articles are substantially free of titania in crystalline form.

Abstract: Methods for forming optical fiber preforms with low-index trenches are disclosed. According to one embodiment, the method includes depositing silica-based glass soot on a bait rod to form a low-index trench region of the optical fiber preform. The silica-based glass soot is deposited such that the low-index trench region has a first density. Thereafter a barrier layer having a second density greater than the first density is formed around the low-index trench region. Therafter, an overclad region is deposited around the barrier layer. The bait rod is then removed from a central channel of the trench-overclad assembly. A separate core assembly is inserted into the central channel. A down-dopant gas is then directed through the central channel of the trench-overclad assembly as the trench-overclad assembly is heated to dope the low-index trench region. The barrier layer prevents diffusion of the down-dopant from the low-index trench region into the overclad region.

Abstract: A method of forming an optical element is provided. The method includes producing silica-based soot particles using chemical vapor deposition, the silica-based soot particles having an average particle size of between about 0.05 ?m and about 0.25 ?m. The method also includes forming a soot compact from the silica-based soot particles and doping the soot compact with a halogen in a closed system by contacting the silica-based soot compact with a halogencontaining gas in the closed system at a temperature of less than about 1200° C.

Abstract: Disclosed herein are methods for regenerating metal catalysts used in the purification of inert gases for use in fiber draw furnaces and other applications. The methods described herein can regenerate metal catalysts alone or in combination with molecular sieves. The methods disclosed herein are able to prevent the formation and retention of unwanted byproducts during and after the regeneration process, thereby efficiently converting oxidized catalysts to their reduced or elemental form. Gases purified with catalysts regenerated by the methods disclosed herein, when used in fiber draw furnaces and similar applications, can lead to extended equipment lifetimes and higher-quality products due to the lack of degradation by contaminants in the gas stream.

Abstract: Bromine doping of silica glass is demonstrated. Bromine doping can be achieved with SiBr4 as a precursor. Bromine doping can occur during heating, consolidation or sintering of a porous silica glass body. Doping concentrations of bromine increase with increasing pressure of the doping precursor and can be modeled with a power law equation in which doping concentration is proportional to the square root of the pressure of the doping precursor. Bromine is an updopant in silica and the relative refractive index of silica increases approximately linearly with doping concentration. Bromine can be used as a dopant for optical fibers and can be incorporated in the core and/or cladding regions. Core doping concentrations of bromine are sufficient to permit use of undoped silica as an inner cladding material in fibers having a trench in the refractive index profile. Co-doping of silica glass with bromine and chlorine is also demonstrated.

Abstract: Disclosed herein are methods for regenerating metal catalysts used in the purification of inert gases for use in fiber draw furnaces and other applications. The methods described herein can regenerate metal catalysts alone or in combination with molecular sieves. The methods disclosed herein are able to prevent the formation and retention of unwanted byproducts during and after the regeneration process, thereby efficiently converting oxidized catalysts to their reduced or elemental form. Gases purified with catalysts regenerated by the methods disclosed herein, when used in fiber draw furnaces and similar applications, can lead to extended equipment lifetimes and higher-quality products due to the lack of degradation by contaminants in the gas stream.

Abstract: A doped silica-titania (“DST”) glass article that includes a glass article having a glass composition comprising a silica-titania base glass containing titania at 7 to 14 wt. % and a balance of silica, and a dopant selected from the group consisting of (a) F at 0.7 to 1.5 wt. %, (b) B2O3 at 1.5 to 5 wt. %, (c) OH at 1000 to 3000 ppm, and (d) B2O3 at 0.5 to 2.5 wt. % and OH at 100 to 1400 ppm. The glass article has an expansivity slope of less than about 1.3 ppb/K2 at 20° C. For DST glass articles doped with F or B2O3, the OH level can be held to less than 10 ppm, or less than 100 ppm, respectively. In many aspects, the DST glass articles are substantially free of titania in crystalline form.

Abstract: Small-radius coated optical fibers having large mode field diameter and low bending losses. The coated fiber may have an outer radius of 110 ?m or less, while providing a mode field diameter of 9.0 ?m or greater and a bending loss when wrapped about a 15 mm mandrel of 0.5 dB/km or less at wavelength of 1550 nm. The coated fiber may have a mode field diameter of 9.2 ?m or greater and may have a bending loss at 1550 nm of 0.25 dB/km or less when wrapped about a 20 mm mandrel or a bending loss at 1550 nm of 0.02 dB/km or less when wrapped about a 30 mm mandrel.

Abstract: A method for forming an optical quality glass is provided. The method includes contacting silica soot particles with a hygroscopic additive, forming a silica soot compact, and removing the hygroscopic additive from the silica soot compact. A method of forming a cladding portion of an optical fiber preform is also provided.

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

Abstract: Small-radius coated optical fibers having large mode field diameter and low bending losses. The coated fiber may have an outer radius of 110 ?m or less, while providing a mode field diameter of 9.0 ?m or greater and a bending loss when wrapped about a 15 mm mandrel of 0.5 dB/km or less at wavelength of 1550 nm. The coated fiber may have a mode field diameter of 9.2 ?m or greater and may have a bending loss at 1550 nm of 0.25 dB/km or less when wrapped about a 20 mm mandrel or a bending loss at 1550 nm of 0.02 dB/km or less when wrapped about a 30 mm mandrel.

Abstract: This disclosure is directed to a silica-titania-niobia glass and to a method for making the glass. The composition of the silica-titania-niobia (SiO2—TiO2—Nb2O5) glass, determined as the oxides, is Nb2O5 in an amount in the range of 0.005 wt. % to 1.2 wt. %, TiO2 in an amount in the range of 5 wt. % to 10 wt. %, and the remainder of glass is SiO2. In the method, the STN glass precursor is consolidated into a glass by heating to a temperature of 1600° C. to 1700° C. in flowing helium for 6 hours to 10 hours. When this temperature is reached, the helium flow can be replaced by argon for the remainder of the time. Subsequently the glass is cooled to approximately 1050° C., and then from 1050° C. to 700° C. followed by turning off the furnace and cooling the glass to room temperature at the natural cooling rate of the furnace.

Abstract: The disclosure relates to methods of forming a vessel and to the resulting vessel. The vessel may be formed by providing a first fumed silica soot layer comprised of primary particles of fumed silica soot, and then providing over the first fumed silica soot layer a second fumed silica soot layer comprised of agglomerated particles formed into an agglomerated form from primary particles of fumed silica soot. The primary particles of the first fumed silica soot layer may have a substantially uniform density distribution, and the agglomerated particles of the second fumed silica soot layer may have a substantially non-uniform density distribution. The methods may include consolidating the first and second soot layers together to form a consolidated body.

Abstract: According to some embodiments a single mode fiber includes: a germania doped central core region having outer radius r1 and relative refractive index ?1; and a cladding region comprising (i) a first inner cladding region having an outer radius r2>6 microns and relative refractive index ?2 and 0.3?r1/r2?0.85; and (ii) a second inner cladding region having an outer radius r3>9 microns and comprising a minimum relative refractive index ?3, wherein said second inner cladding region has at least one region with a relative refractive index delta that becomes more negative with increasing radius; and (iii) an outer cladding region surrounding the second inner cladding region and comprising relative refractive index ?4, wherein ?1>?2>?3, ?3<?4.

Abstract: Described herein are coated glass or glass-ceramic articles having improved reflection resistance. Further described are methods of making and using the improved articles. The coated articles generally include a glass or glass-ceramic substrate and a nanoporous Si-containing coating disposed thereon. The nanoporous Si-containing coating is not a free-standing adhesive film, but a coating that is formed on or over the glass or glass-ceramic substrate.

Abstract: Optical preforms and methods for forming optical preforms are disclosed. According to one embodiment, a method for producing an optical preform includes compressing silica-based glass soot to form a porous optical preform comprising a soot compact. The porous optical preform is heated to a dwell temperature greater than or equal to 100° C. Thereafter, the porous optical preform is humidified at the dwell temperature in a water-containing atmosphere having a dew point greater than or equal to 30° C. to form a humidified porous optical preform. The soot compact portion of the humidified porous optical preform generally comprises greater than or equal to 0.5 wt. % water.

Abstract: A method of forming a cladding portion of an optical fiber preform assembly includes positioning a glass core cane in a mold cavity and loading the mold cavity with silica glass soot. The silica glass soot is compressed in an axial direction as the vibratory energy is applied to the mold body to form a soot compact around the glass core cane, wherein the soot compact is the cladding portion of an optical fiber preform assembly and the glass core cane is a core portion of the optical fiber preform assembly.

Abstract: A method of making an optical fiber preform comprising in order: (i) manufacturing a glass preform with at least one porous layer; (ii) exposing the glass preform with at least one porous layer to a fluorine precursor at temperature below 1295° C. to make a fluorine treated preform, and (iii) exposing the fluorine treated glass preform with at least one porous silica based layer the temperatures above 1400° C. to completely sinter the preform. Preferably, the porous silica based layer of the glass preform exposed to fluorine precursor has average density of at least 0.7 g/cm3 but less than 1.9 g/cm3.

Abstract: A method and apparatus for making an optical fiber preform. The apparatus has an outer wall and an inner wall. The outer wall surrounds the inner wall and the inner wall surrounds an inner cavity of the apparatus. A core rod is deposited in the inner cavity after which particulate glass material, such as glass soot, is deposited in the inner cavity around the core rod. The core rod has at least 10 percent of the final cladding soot already applied thereto. A radially inward pressure is applied against the particulate glass material to pressurize the particulate glass material against the core rod.

Abstract: Small-radius coated optical fibers having large mode field diameter and low bending losses. The coated fiber may have an outer radius of 110 ?m or less, while providing a mode field diameter of 9.0 ?m or greater and a bending loss when wrapped about a 15 mm mandrel of 0.5 dB/km or less at wavelength of 1550 nm. The coated fiber may have a mode field diameter of 9.2 ?m or greater and may have a bending loss at 1550 nm of 0.25 dB/km or less when wrapped about a 20 mm mandrel or a bending loss at 1550 nm of 0.02 dB/km or less when wrapped about a 30 mm mandrel.