An optical fiber with low attenuation is provided. The fiber is produced under conditions that reduce fictive temperature. Processing includes maintaining the fiber at temperatures at or near the glass transition temperature (T.sub.g) for an extended period of time. For silica-based fibers, the preferred temperatures are temperatures between 1000 C. and 1700 C. The extended residence times are achieved in a continuous fiber manufacturing process by increasing the path length of the fiber through a processing region maintained at temperatures between 1000 C. and 1700 C. The increased path length is achieved by including one or more fluid bearing devices in the processing region. The extended residence time in the processing region allows the structure of the glass fiber to relax more completely and to more closely approach the equilibrium state. The more relaxed glass structure leads to a lower fictive temperature and provides fibers with lower attenuation.

Provides is low scattering silica glass suitable as a material of an optical communication fiber. Silica glass has a fictive temperature of at least 1,000 C. and a void radius of at most 0.240 nm, as measured by positron annihilation lifetime spectroscopy. A method for heat-treating silica glass is also provided, which comprises holding silica glass to be heat-treated in an atmosphere at a temperature of at least 1,200 C. and at most 2,000 C. under a pressure of at least 30 MPa, and cooling the silica glass at an average temperature-decreasing rate of at least 40 C./min during cooling within a temperature range of from 1,200 C. to 900 C. A method for heat-treating silica glass also comprises holding silica glass to be heat-treated in an atmosphere at a temperature of at least 1,200 C. and at most 2,000 C. under a pressure of at least 140 MPa, and cooling the silica glass in an atmosphere under a pressure of at least 140 MPa during cooling within a temperature range of from 1,200 C. to 900 C.

A method for manufacturing an optical fiber includes: drawing an optical fiber from an optical fiber preform in a drawing furnace; and cooling the optical fiber in an annealing furnace. When the optical fiber enters the annealing furnace, a temperature difference between a temperature of the optical fiber and a fictive temperature of glass in a core of the optical fiber is 300 C. or less. The optical fiber is cooled for 0.01 seconds or more in the annealing furnace so that the temperature of the optical fiber becomes 1300 C. or more and 1800 C. or less.

An optical fiber with low attenuation is provided. The fiber is produced under conditions that reduce fictive temperature. Processing includes maintaining the fiber at temperatures at or near the glass transition temperature (T.sub.g) for an extended period of time. For silica-based fibers, the preferred temperatures are temperatures between 1000 C. and 1700 C. The extended residence times are achieved in a continuous fiber manufacturing process by increasing the path length of the fiber through a processing region maintained at temperatures between 1000 C. and 1700 C. The increased path length is achieved by including one or more fluid bearing devices in the processing region. The extended residence time in the processing region allows the structure of the glass fiber to relax more completely and to more closely approach the equilibrium state. The more relaxed glass structure leads to a lower fictive temperature and provides fibers with lower attenuation.

An optical fiber comprises, from a center to a periphery, a fiber core of undoped silica; a cladding layer; and a coating of polyacrylate, wherein the fiber core has a radius of 5 to 7 m and an ellipticity of less than 1.5%, the cladding layer with an ellipticity of less than 0.4% comprises inner, intermediate, and outer cladding layers, the inner cladding layer being doped with fluorine of 5 to 12 m thickness, and refractive index difference to fiber core of 0.4 to 0.2%, the outer cladding layer being undoped quartz of 25 to 45 m thickness, and the coating comprises an inner coating of 25 to 40 m thickness, and an outer coating of 25 to 35 m thickness and an ellipticity of less than 2%. The optical fiber has high durability and large effective transmission area, a method and system for preparing such optical fiber are also disclosed.

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.

A single mode optical fiber having a core made from silica and less than or equal to about 6.5 weight % germania and having a maximum relative refractive index .sub.1MAX. The optical fiber also has an inner cladding surrounding the core and having a minimum relative refractive index .sub.2MIN. A difference between a softening point of the core and a softening point of the inner cladding is less than or equal to about 20 C., and .sub.1MAX>.sub.2MIN. The single mode optical fiber may also have an outer cladding surrounding the inner cladding made from silica or SiON. The outer cladding has a maximum relative refractive index .sub.3MAX, and .sub.3MAX>.sub.2MIN. A method for manufacturing an optical fiber includes providing a preform to a first furnace, the preform, drawing the optical fiber from the preform, and cooling the drawn optical fiber in a second furnace.

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 organic-inorganic composite, including: a discontinuous phase having a plurality of adjacent and similarly oriented fibers of an inorganic material; and a continuous organic phase having a thermoplastic polymer, such that the continuous organic phase surrounds the plurality of adjacent and similarly oriented fibers of the inorganic material, and the organic-inorganic composite is a plurality of adjacent and similarly oriented fibers of inorganic material contained within a similarly oriented host fiber of the thermoplastic polymer. Also disclosed are methods of making and using the composite.

Preform for an optical waveguide containing a core with a non-circular geometry and at least one cladding layer, in which the dopand concentration of the cladding layer is increased compared to the dopand concentration of a preform with circular core geometry and identical NA. A method for the production of a preform for an optical fiber is provided. An optical waveguide with a nominal dopand concentration of c(eff)Fc(nom) in at least one cladding layer is also provided.