A curable glass coating composition including 5-70 wt % aliphatic polycarbonate diol, 5-60 wt % crosslinker, 1-20 wt % extender, 4-20 wt % fatty alcohol, and 2-30 wt % crystalline or amorphous powder filler material, and optionally 2-20 wt % aliphatic polyester polyol and 2-20 wt % cycloaliphatic epoxy. The coating composition can be applied to a glass substrate and cured to form a decorative cured polyurethane coating layer on the substrate that has improved caustic and UV resistance.

[Problem] To provide a radiation curable resin composition that is suitable as a primary material of an optical fiber and has a fast curing rate by irradiation with radiation.

[Solution] A radiation polymerizable composition for forming a primary coating layer of an optical fiber, the radiation polymerizable composition comprising: (A) a urethane oligomer comprising a structure represented by formula (I) below:

##STR00001## wherein R is a vinyl group and * is a bond; (B) one or more compounds of: (i) maleic anhydride, (ii) a compound represented by formula (II):

##STR00002## wherein R.sup.1 is a single bond or an alkanediyl group comprising 1 to 6 carbon atoms, and R.sup.2 is a hydrogen atom, a hydroxy group, or a group represented by predetermined formula (II-1) or formula (II-2), or (iii) a compound represented by formula (III):

##STR00003## wherein R.sup.5 is an alkanediyl group comprising 1 to 6 carbon atoms; and (C) a radiation polymerization initiator.

Apparatus, systems, and methods that provide coats on a glass optical fiber including of an inner layer and an outer layer. The method includes two steps. First, a conductive polymer coating is applied to the optical fiber as it is being produced. Second, a protective coating is applied to that conductive polymer coating. The conductive polymer coating is applied immediately after the fiber is drawn from preform to fiber.

A method for producing a coated optical fiber includes coating, using a coating die, a circumferential side surface of an optical fiber with a coating material by passing the optical fiber sequentially through an insertion hole portion, a_ liquid retaining chamber (21), and a_coating hole portion opposed to the insertion hole portion, while the coating material in the liquid retaining chamber is supplied under pressure to the coating hole portion, in which a pressure difference ΔP (MPa) between a liquid pressure of the coating material in the liquid retaining chamber and a pressure outside the coating die, a viscosity .Math. (Pa.Math.s) of the coating material in the liquid retaining chamber, and a length L (mm) of the coating hole portion in an extending direction satisfy a relationship of ΔP/.Math.L ≤ 0.15.

A method for producing a coated optical fiber includes coating, using a coating die, a circumferential side surface of an optical fiber with a coating material by passing the optical fiber sequentially through an insertion hole portion, a_ liquid retaining chamber (21), and a_coating hole portion opposed to the insertion hole portion, while the coating material in the liquid retaining chamber is supplied under pressure to the coating hole portion, in which a pressure difference ΔP (MPa) between a liquid pressure of the coating material in the liquid retaining chamber and a pressure outside the coating die, a viscosity .Math. (Pa.Math.s) of the coating material in the liquid retaining chamber, and a length L (mm) of the coating hole portion in an extending direction satisfy a relationship of ΔP/.Math.L ≤ 0.15.

An optical fiber according to an embodiment includes a core, a cladding, and a coating layer. At the boundary between the core and the cladding, the local sound velocity decreases in the direction from the core side toward the cladding side. At least in the cladding, the local sound velocity changes continuously in a radial direction. Further, the line width of the Brillouin gain of the light beam guided by the fundamental mode is 60 MHz or more.

A method is described of manufacturing an optical sensing element for detecting a presence and/or determining a concentration of an analyte in a fluid medium, in particular in an aqueous medium. The optical sensing element includes an optical waveguide (e.g. an optical fiber) comprising an optically transparent material for guiding light through the sensing element along a flightpath. The optical sensing element further includes an inorganic coating for adsorbing the analyte from the fluid medium and an adhesion promotion layer formed between the optical waveguide and the inorganic coating. The adhesion promotion layer includes an adhesion promotion material for promoting adhesion of the inorganic material.

A method of fabricating an optical fiber ribbon is provided, the method including arranging a plurality of optical fibers adjacent to each other along a length of the optical fiber ribbon, applying an adhesive to the plurality of optical fibers, intermittently exposing the adhesive to a curing catalyst in at least one interstice between two adjacent optical fibers of the plurality of optical fibers to create bonding regions along the length of the optical fiber ribbon, and removing uncured adhesive from the plurality of optical fibers.

An eccentric state determining method which is performed by a controller and for determining a state of eccentricity of a coating of a glass fiber with respect to the glass fiber. The coating is formed around the glass fiber. The method includes acquiring measurement values for an outer diameter of the optical fiber at positions along a longitudinal direction of the optical fiber, calculating a standard deviation of the measurement values, and determining the state of the eccentricity based on the standard deviation.

A technique is described for fabricating one or more optical devices in a carbon-coated optical fiber. A photosensitive optical fiber is provided having a hermetic carbon coating. Further provided is a laser having a beam output that is configured to inscribe one or more refractive index modulations into the optical fiber through the hermetic carbon layer while leaving the hermetic carbon layer intact. The laser is used to inscribe one or more optical devices into the optical fiber through the hermetic carbon layer.