According to some embodiments a method of processing an optical fiber comprises the steps of: (i) drawing the fiber at a drawing rate of at least 30 m/sec; and (ii) cooling the drawn fiber in a gas at an average cooling rate less than 5000° C./s, such that said cooling reduces the temperature of the fiber from an entering temperature in the range between 1500° C. and 1700° C. to another temperature in the range between 1200° C. and 1400° C., the gas being at a temperature between 800° C. and 1500° C.; and the thermal conductivity κ of the gas being not greater than 1.5×10.sup.−4 cal/cm-s-K for at least one temperature within a range of 800° C. to 1500° C. at one atm (atmosphere) pressure absolute.

A manufacturing method for an optical fiber, includes: drawing, while heating in a heating furnace, a lower end of an optical fiber preform that is to be an optical fiber having a core consisting of silica glass containing a rare earth element compound. The heating furnace has a temperature profile in which a temperature of the heating furnace increases to a maximum temperature T.sub.max and then decreases from an upstream side of the heating furnace toward a downstream side of the heating furnace. The temperature profile has a changing point at which the temperature decreases more steeply on the downstream side from a position where the maximum temperature T.sub.max is reached. At the maximum temperature, a temperature of the silica glass is higher than or equal to a glass transition temperature and the silica glass is in a single phase.

An optical fiber for a fiber laser includes a core to which a rare-earth element is added, a first cladding formed around the core; and a second cladding formed around the first cladding, and excitation light is guided from at least one end of the first cladding to excite the rare-earth element to output a laser oscillation light. An addition concentration of the rare-earth element to the core is different in a longitudinal direction of the optical fiber for a fiber laser, and a core diameter and a numerical aperture of the optical fiber for a fiber laser are constant in the longitudinal direction of the optical fiber for a fiber laser.

An optical fiber manufacturing method includes: melting and drawing an optical fiber preform to form a glass fiber; cooling the glass fiber while inserting the glass fiber into a tubular slow-cooling device from an inlet end toward an outlet end thereof, and lowering an inner wall temperature of the slow-cooling device below a temperature of the glass fiber and providing a pressure gradient in which a pressure increases in a direction from the inlet end toward the outlet end inside the slow-cooling device when cooling the glass fiber, wherein the average pressure change dP/dL in a moving direction of the glass fiber inside the slow-cooling device satisfies the following Formula (1) when the tube inner diameter of the slow-cooling device is defined as D [m] and the length of an internal space of the slow-cooling device in the moving direction of the glass fiber is defined as L [m].

(πD.sup.2/4)×dP/dL≦0.03  (1)

A cooling device system for cooling optical fiber includes a plurality of bodies (202), each body having a top surface (210) and an opposing bottom surface (212); an opening (204) within each of the plurality of bodies extending from the top surface through the body to the bottom surface, wherein the opening is configured to pass an optical fiber (10) through the body; and one or more air outlets (208) within the body configured to direct air to contact the optical fiber as it passes through the opening, wherein the air flowing out of the one or more openings has an average velocity of about 20 m/s to about 350 m/s.

A method for manufacturing an optical fiber includes: gripping a preform by a gripper that includes an aligner; forming a bare fiber by melting the preform in a melting furnace; cooling the bare fiber by blowing gas in a cooler; applying a resin and coating an outer circumference of the bare fiber; curing the resin; acquiring input information that changes a flow rate of the gas blown to the bare fiber in the cooler; and adjusting based on the input information an entry position of the bare fiber into the cooler by controlling the aligner and moving the preform.

A light diffusing optical fiber includes a core, a cladding surrounding the core, an outer surface, and a plurality of scattering structures positioned within the core, the cladding, or both the core and the cladding. The plurality of scattering structures are configured to scatter guided light towards the outer surface, such that light including a wavelength of from about 450 nm to about 650 nm diffusing through the outer surface along a diffusion length of the light diffusing optical fiber includes a spectral attenuation percent relative range of about 15% or less.

A method for manufacturing an optical fibre, in which a preform is inserted into a furnace, the preform is drawn via an outlet of the furnace, and at least one laser beam is applied to a working zone of the drawn preform, each laser beam being power-modulated according to a modulation frequency. A device for manufacturing an optical fibre is also provided.

Provided is a method of fabricating an optical fiber glass base material, the method including a first step for dehydrating an optical fiber porous base material while causing a gas that includes at least a halogen or argon to distribute within a quartz core tube that accommodates the optical fiber porous base material; a second step for, after the first step, at least partially ventilating within the quartz core tube by causing a gas having helium as a main component to distribute within the quartz core tube; and a third step for, after the second step, transparently vitrifying the optical fiber porous base material while causing the gas having helium as a main component to distribute within the quartz core tube.

An optical fiber manufacturing method includes: drawing an optical fiber preform to form a bare optical fiber; cooling the bare optical fiber by a non-contact direction changer; adjusting a temperature of the bare optical fiber in a temperature adjusting unit disposed downstream of the non-contact direction changer and upstream of a coating unit; disposing, in the coating unit, an uncured coating layer that comprises a resin precursor on an outer periphery of the bare optical fiber; and curing the uncured coating layer in a curing unit.