A doped silica-titania glass article is provided that includes a glass article having a glass composition comprising (i) a silica-titania base glass, (ii) a fluorine dopant, and (iii) a second dopant. The fluorine dopant has a concentration of fluorine of up to 5 wt. % and the second dopant comprises one or more oxides selected from the group consisting of Al, Nb, Ta, B, Na, K, Mg, Ca and Li oxides at a total oxide concentration from 50 ppm to 6 wt. %. Further, the glass article has an expansivity slope of less than 0.5 ppb/K.sup.2 at 20 C. The second dopant can be optional. The composition of the glass article may also contain an OH concentration of less than 100 ppm.

A method for producing a blank of iron-doped silica glass with high silicic acid content for use as heat protection glass is provided. The method involves: (a) producing an iron-doped SiO.sub.2 soot body which contains iron in a first oxidation state Fe.sup.3+ by flame hydrolysis of a silicon-containing and an iron-containing starting substance, (b) drying the soot body to obtain a mean hydroxyl group content of less than 10 ppm by weight, and (c) vitrifying the soot body under a reducing atmosphere that is suitable for at least partially reducing the iron from the first oxidation state Fe.sup.3+ to a second, lower oxidation state Fe.sup.2+. A blank is obtained having an iron content between 0.1 and 1% by weight which exhibits an internal transmission of at most 40% in the infrared wavelength range and an internal transmission of at least 85% in the visible spectral range.

A method for forming an optical fiber preform and fibers drawn from the preform. The method includes forming a soot cladding monolith, inserting a consolidated core cane into the internal cavity, and processing the resulting core-cladding assembly to form a preform. Processing may include exposing the core-cladding assembly to a drying agent and/or dopant precursor, and sintering the core-cladding assembly in the presence of a reducing agent to densify the soot cladding monolith onto the core cane to form a preform. The preform features low hydroxyl content and low sensitivity to hydrogen. Fibers drawn from the preform exhibit low attenuation losses from absorption by the broad band centered near 1380 nm.

The Ti.sup.3+ ions present in Ti-doped silica glass cause a brown staining of the glass, causing inspection of the lens to become more difficult. Known methods for reducing Ti.sup.3+ ions in favor of Ti.sup.4+ ions in Ti-doped silica glass include a sufficiently high proportion of OH-groups and carrying out an oxygen treatment prior to vitrification, which both have disadvantages. In order to provide a cost-efficient production method for Ti-doped silica glass, which at a hydroxyl group content of less than 120 ppm shows an internal transmittance (sample thickness 10 mm) of at least 70% in the wavelength range of 400 nm to 1000 nm, the TiO.sub.2SiO.sub.2 soot body is subjected to a conditioning treatment with a nitrogen oxide prior to vitrification. The blank produced in this way from Ti-doped silica glass has the ratio Ti.sup.3+/Ti.sup.4+510.sup.4.

A quartz glass fibre includes a fibre core of quartz glass produced by modified chemical vapor deposition (MCVD). A fluorine-doped radial layer is provided on the fibre core. A cladding layer of quartz glass contains chlorine and covers the fluorine-doped radial layer to define a hydrogen barrier around the fibre core in response to being irradiated by defect-generating ultra-violet (UV) radiation. The cladding layer has at least one of a combination of E defects and non-bridging oxygen hole center (NBOHC) defects and a combination of SiOH and SiH compounds.

A method of manufacturing a quartz glass fibre includes producing a quartz glass primary preform by modified chemical vapor deposition (MCVD) in a quartz glass substrate tube and inserting the quartz glass primary preform into a glass jacketing tube. Defect-generating UV radiation is irradiated into the cross-sectional area of the glass jacketing tube while combining the quartz glass primary preform with the glass jacketing tube in the jacketing process to form a cladding layer to a secondary preform. A quartz glass fibre is pulled from the secondary preform.

A method for producing a silica glass blank co-doped with titanium and fluorine for use in EUV lithography includes (a) producing a TiO.sub.2SiO.sub.2 soot body by flame hydrolysis of silicon- and titanium-containing precursor substances, (b) fluorinating the TiO.sub.2SiO.sub.2 soot body to form a fluorine-doped TiO.sub.2SiO.sub.2 soot body, (c) treating the fluorine-doped TiO.sub.2SiO.sub.2 soot body in a water vapor-containing atmosphere to form a conditioned soot body, and (d) vitrifying the conditioned soot body to form the blank. The blank has an internal transmission of at least 60% in the wavelength range of 400 to 700 nm at a sample thickness of 10 mm, a mean OH content in the range of 10 to 100 wt. ppm and a mean fluorine content in the range of 2,500 to 10,000 wt. ppm. Titanium is present in the blank in the oxidation forms Ti3.sup.+ and Ti.sup.4+.

A blank made of titanium-doped silica glass for a mirror substrate for use in EUV lithography is provided. The blank includes a surface portion to be provided with a reflective film and having an optically used area (CA) over which a coefficient of thermal expansion (CTE) has a two-dimensional inhomogeneity (dCTE) distribution profile averaged over a thickness of the blank. A maximum inhomogeneity (dCTE.sub.max) of less than 5 ppb/K is defined as a difference between a CTE maximum value and a CTE minimum value. The dCTE.sub.max is at least 0.5 ppb/K. The CA forms a non-circular area having a centroid. The dCTE distribution profile is not rotation-symmetrical and is defined over the CA, such that straight profile sections normalized to a unit length and extending through the centroid of the area yield a dCTE family of curves forming a curve band with a bandwidth of less than 0.5dCTE.sub.max.

The invention relates to microstructured optical fibers that are drawn through hollow channels and have a core region, which extends along a fiber longitudinal axis, and a jacket region surrounding the core region. The aim of the invention is to reduce a damping increase due to corrosion and to reduce the emission of chlorine on the basis of the microstructured optical fibers. This is achieved in that at least some of the hollow channels are delimited by a wall material made of synthetic quartz glass which has a chlorine concentration of less than 300 wt. ppm and oxygen deficiency centers in a concentration of at least 21015 cm-3.