A method of controlling the temperature of an optical fiber is provided that includes the steps of: providing an energy transfer member configured to accept or provide thermal energy, the energy transfer member defines an energy transfer surface; passing an optical fiber proximate the energy transfer member such that a gap is defined between the optical fiber and the energy transfer surface; and transferring thermal energy between the optical fiber and the energy transfer member via conduction across the gap.

An optical fiber production method includes: drawing an optical fiber preform in a drawing furnace; and cooling the optical fiber. The optical fiber is passed through a plurality of annealing furnaces while the optical fiber is cooled. While the optical fiber is cooled, temperatures of the annealing furnaces are set such that the temperature difference is within a range between and including an upper limit and a lower limit of a temperature difference between a temperature of the optical fiber and a fictive temperature of glass constituting a core of the optical fiber at which an increase of a transmission loss of the optical fiber when the fictive temperature of the glass is decreased is less than 0.001 dB/km.

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.

A method of processing an optical fiber includes drawing the optical fiber from a heated glass source, reheating the optical fiber, and cooling the optical fiber under vacuum at a cooling rate less than the cooling rate of the optical fiber in air at 25 C. and 1 atm. Cooling the optical fiber under vacuum is conducted after reheating the optical fiber. Cooling the optical fiber under vacuum reduces the rate of heat transfer from the optical fiber, which may enable further relaxation of the glass and reduction in the fictive temperature of the optical fiber. A system for processing an optical fiber includes a furnace containing a fiber preform, a first positioner, a reheating device, and a treatment device downstream of the reheating device, the treatment device operable to cool the optical fiber under vacuum to reduce the rate of heat transfer from the optical fiber.

A method of making optical fibers that includes controlled cooling to produce fibers having a low concentration of non-bridging oxygen defects and low sensitivity to hydrogen. The method may include heating a fiber preform above its softening point, drawing a fiber from the heated preform and passing the fiber through two treatment stages. The fiber may enter the first treatment stage at a temperature between 1500 C. and 1700 C., may exit the first treatment stage at a temperature between 1200 C. and 1400 C., and may experience a cooling rate less than 5000 C./s in the first treatment stage. The fiber may enter the second treatment stage downstream from the first treatment stage at a temperature between 1200 C. and 1400 C., may exit the second treatment stage at a temperature between 1000 C. and 1150 C., and may experience a cooling rate between 5000 C./s and 12,000 C./s in the second treatment stage. The method may also include redirecting the fiber with a fluid bearing device or an air-turn device.

In some embodiments, a method for processing an optical fiber includes: drawing an optical fiber through a draw furnace, conveying the optical fiber through a flame reheating device downstream from the draw furnace, wherein the flame reheating device comprises one or more burners each comprising: a body having a top surface and an opposing bottom surface, an opening within the body extending from the top surface through the body to the bottom surface, wherein the optical fiber passes through the opening, and one or more gas outlets within the body; and igniting a flammable gas provided by the one or more gas outlets to form a flame encircling the optical fiber passing through the opening, wherein the flame heats the optical fiber by at least 100 degrees Celsius at a heating rate exceeding 10,000 degrees Celsius/second.

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.