A glass composite for use in Extreme Ultra-Violet Lithography (EUVL) is provided. The glass composite includes a first silica-titania glass section. The glass composite further includes a second doped silica-titania glass section mechanically bonded to a surface of the first silica-titania glass section, wherein the second doped silica-titania glass section has a thickness of greater than about 1.0 inch.

A continuous sol-gel process for producing silicate-containing glasses and glass ceramics is proposed, comprising the following steps: (a) continuously feeding a silicon tetraalkoxide, a silicon alkoxide with at least one non-alcoholic functional group and an alcohol into a first reactor (R1), and at least partially hydrolyzing by the addition of a mineral acid to obtain a first product stream (A); (b) continuously providing a second product stream (B) in a second reactor (R2) by feeding a metal alkoxide component or continuously mixing an alcohol and a metal alkoxide component; (c) continuously mixing product streams (A) and (B) in a third reactor (R3) for producing a presol to obtain a third product stream (C); (d) continuously adding water or a diluted acid to the product stream (C) to obtain a sol (gelation); (e) continuously filling the emerging sol into molds to obtain an aquagel; (f) drying the aquagels to obtain xerogels; (g) sintering the xerogels to obtain silicate-containing glasses and glass ceramics.

The present disclosure provides optical fiber preforms formed from core canes having large core-clad ratio, intermediate core-cladding assemblies, and methods for making the preforms and core cladding assemblies. The preforms are made with capped core canes. The capping material has a coefficient of thermal expansion less than the coefficient of thermal expansion of the core cane and more closely matched to or lower than the coefficient of thermal expansion of the surrounding cladding monolith in a cane-in-soot process. Presence of the cap reduces stresses that arise from differential thermal expansion of the core cane and cladding materials and leads to preforms having low defect concentration and low probability of failure during subsequent thermal processing steps.

An optical fiber with low fictive temperature along with a system and method for making the optical fiber are provided. The system includes a reheating stage that heats the fiber along the process pathway to a temperature sufficient to lower the fictive temperature of the fiber by relaxing the glass structure and/or driving the glass toward a more nearly equilibrium state. The fiber is drawn from a preform, conveyed along a process pathway, cooled and subsequently reheated to increase the time of exposure of the fiber to temperatures conducive to lowering the fictive temperature of the fiber. The process pathway may include multiple reheating stages as well as one or more fiber-turning devices.

An optical fiber containing an alkali metal and capable of reducing Rayleigh scattering loss is provided. An optical fiber has a core and a cladding made of silica glass and enclosing the core. The cladding contains fluorine and has a refractive index lower than the refractive index of the core. The core contains first group dopants selected from the group of Na element, K element, or a compound thereof at an average concentration of 0.2 ppm or more and 10 ppm or less. The core also contains second group dopants for reducing the viscosity of silica glass and having a diffusion coefficient of 110.sup.12 cm.sup.2/s or more and smaller than the diffusion coefficient of the first group dopants, by an average concentration of 0.2 ppm or more at a temperature of 2000 C. to 2300 C.

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.

A method of manufacturing a transparent glass article is provided. The manufacturing method includes the following steps (a) to (f): in step (a), a nanocomposite is provided; in step (b), the nanocomposite is subjected to an external stimulus in order to render it remoldable; in step (c), the nanocomposite is remolded into a predetermined shape in order to obtain a primary structure; in step (d), the primary structure is debound in order to obtain a secondary structure having cavities formed therein; in step (e) which is optional, the cavities of the secondary structure are filled with at least one additive; and in step (f), the secondary structure is sintered to obtain the transparent glass article.