A method for manufacturing an SiO.sub.2—TiO.sub.2 based glass upon a target by a direct method, includes a first process of preheating the target and a second process of growing an SiO.sub.2—TiO.sub.2 based glass ingot to a predetermined length upon the target which has been preheated, wherein the target is heated in the first process such that, in the second process, the temperature of growing surface of the glass ingot is maintained at or above a predetermined lower limit temperature.

A system and method for making a thin sintered silica sheet is provided. The method includes providing a soot deposition surface and forming a glass soot sheet by delivering a stream of glass soot particles from a soot generating device to the soot deposition surface. The method includes providing a sintering laser positioned to direct a laser beam onto the soot sheet and forming a sintered glass sheet from the glass soot sheet by delivering a laser beam from the sintering laser onto the glass soot sheet. The sintered glass sheet formed by the laser sintering system or method is thin, has low surfaces roughness and/or low contaminant levels. The system is also configured to produce a sheet having low degrees of warp and/or low fictive temperatures.

Layered glass structures and fabrication methods are described. The methods include depositing soot on a dense glass substrate to form a composite structure and sintering the composite structure to form a layered glass structure. The dense glass substrate may be derived from an optical fiber preform that has been modified to include a planar surface. The composite structure may include one or more soot layers. The layered glass structure may be formed by combining multiple composite structures to form a stack, followed by sintering and fusing the stack. The layered glass structure may further be heated to softening and drawn to control linear dimensions. The layered glass structure or drawn layered glass structure may be configured as a planar waveguide.

A method includes impregnating a region of a glass sheet with a filler material in a liquid state. The glass sheet includes a plurality of glass soot particles. The filler material is solidified subsequent to the impregnating step to form a glass/filler composite region of the glass sheet.

Laser waveguides, methods and systems for forming a laser waveguide are provided. The waveguide includes an inner cladding layer surrounding a central axis and a glass core surrounding and located outside of the inner cladding layer. The glass core includes a laser-active material. The waveguide includes an outer cladding layer surrounding and located outside of the glass core. The inner cladding, outer cladding and/or core may surround a hollow central channel or bore and may be annular in shape.

A method includes impregnating a region of a glass sheet with a filler material in a liquid state. The glass sheet includes a plurality of glass soot particles. The filler material is solidified subsequent to the impregnating step to form a glass/filler composite region of the glass sheet.

One aspect is a method for producing a hollow porous quartz glass base material. Even when the hollow porous quartz glass base material is produced in large weight and high bulk density, the ease of target extraction is maintained and target extraction is performed stably. The method includes preparing a heat resistant substrate, which has an outer surface on which SiO.sub.2 particles are deposited, the outer surface having a surface roughness in which the maximum height Rz is less than 9 μm and the arithmetic average roughness Ra is less than 1 μm. The heat resistant substrate is rotated and SiO.sub.2 particles are deposited on the outer surface of the heat resistant substrate to form a glass particulate deposit. The heat resistant substrate is extracted from the glass particulate deposit to produce the base material.

An additive manufacturing process includes forming an object material stack using sheet materials without use of binder material between the sheet materials and forming features of the cross-sectional layers of a 3D object in the corresponding sheet materials. Another process involves forming features of the cross-sectional layers of a 3D object in soot layers of a laminated soot sheet. A manufactured article includes three or more glass layers laminated together without any binder material between the glass layers. At least one of the glass layers is composed of silica or doped silica, and at least one feature is formed in at least one of the glass layers.

Laser waveguides, methods and systems for forming a laser waveguide are provided. The waveguide includes an inner cladding layer surrounding a central axis and a glass core surrounding and located outside of the inner cladding layer. The glass core includes a laser-active material. The waveguide includes an outer cladding layer surrounding and located outside of the glass core. The inner cladding, outer cladding and/or core may surround a hollow central channel or bore and may be annular in shape.

An additive manufacturing process includes forming an object material stack using sheet materials without use of binder material between the sheet materials and forming features of the cross-sectional layers of a 3D object in the corresponding sheet materials. Another process involves forming features of the cross-sectional layers of a 3D object in soot layers of a laminated soot sheet. A manufactured article includes three or more glass layers laminated together without any binder material between the glass layers. At least one of the glass layers is composed of silica or doped silica, and at least one feature is formed in at least one of the glass layers.