A resin composition for secondary coating of an optical fiber is a resin composition comprising: a photopolymerizable compound comprising a urethane (meth)acrylate having a number average molecular weight of 10000 or more and 40000 or less; and a photopolymerization initiator, the content of the urethane (meth)acrylate is 0.05 parts by mass or more and 15 parts by mass or less based on the total amount of the resin composition of 100 parts by mass, and the urethane (meth)acrylate is a reaction product of a polyol having a number average molecular weight of 1800 or more and 4500 or less, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

This resin composition for secondary coating of an optical fiber contains: at least one type of polyoxyalkylene monoalkyl ether compound selected from the group consisting of a polyoxyalkylene monoalkyl ether having a number average molecular weight of 2500-10,000 and a derivative of said polyoxyalkylene monoalkyl ether; a photopolymerizable compound; and a photopolymerization initiator.

A method for manufacturing an optical fiber preform includes: producing a core preform including a core portion made of transparent glass and a first cladding layer obtained by adding fluorine to the core portion; and forming, on an outer periphery of the first cladding layer, a second cladding layer made of glass having a refractive index higher than that of the first cladding layer. Further, a refractive index profile is formed in the first cladding layer due to a fluorine concentration profile, the refractive index profile being provided at least near a boundary surface with the second cladding layer and having a profile such that a refractive index difference between a refractive index of the first cladding layer and a refractive index of the second cladding layer decreases in accordance with a reduction in a distance from the boundary surface with the second cladding layer.

An optical fiber comprises a glass fiber comprising a core and a cladding, and a coating resin layer, wherein the coating resin layer has a primary resin layer being in contact with the glass fiber and coating the glass fiber, and a secondary resin layer coating the primary resin layer, and the primary resin layer and the secondary resin layer are resin layers containing inorganic oxide particles.

A fiber optic cable terminal proximally terminates a stub cable carrying one or more optical fibers. The stub cable is structurally adapted to be advanced through at least a portion of a conduit by distally pushing a distal end of the stub cable from a location that is proximal to a proximal end of the conduit and without applying any pulling force at any location that is distal to the proximal end of the conduit.

An optical fiber includes a glass fiber including: a core and a cladding; and a coating resin layer coating the glass fiber in contact with the glass fiber; wherein the coating resin layer has a primary resin layer coating the glass fiber in contact with the glass fiber and a secondary resin layer coating the primary resin layer, the primary resin layer contains a cured product of a first resin composition containing a photopolymerizable compound and a phosphine oxide-based photopolymerization initiator, the secondary resin layer contains a cured product of a second resin composition containing a photopolymerizable compound and a phosphine oxide-based photopolymerization initiator, and an amount of the phosphine oxide-based photopolymerization initiator remaining unreacted in the coating resin layer is 0.5 mass % or less.

An optical fiber includes a glass fiber, and a resin coating layer covering an outer circumference of the glass fiber. In a spectrum acquired by measuring an amount of eccentricity of the glass fiber from a central axis based on an outer circumference of the resin coating layer at a plurality of measurement points set at a predetermined interval in an axial direction of the glass fiber and applying Fourier transform of a waveform representing the amount of eccentricity at each of the plurality of measurement points, a largest value of amplitude of the amount of eccentricity is 6 μm or less.

The present disclosure provides coating compositions and cured products formed from the coating compositions. The cured products can be formed at high cure speeds from the coating compositions and feature low Young's modulus, high tear strength, and/or high tensile toughness. The cured products can be used as primary coatings for optical fibers. The primary coatings provide good microbending performance and are resistant to defect formation during fiber coating processing and handling operations. The coating compositions include an oligomer, an alkoxylated monofunctional acrylate monomer, and preferably, an N-vinyl amide compound.

A wellbore optical fiber measurement system for measuring data in a lateral wellbore that includes a flexible optical fiber. The optical fiber includes a waveguide coated with a coating, wherein the optical fiber has an effective density ρ.sub.eff.sub.fiber and an effective axial Young modulus E.sub.eff.sub.fiber and wherein the product $\left(\frac{{\rho }_{{\mathrm{eff}}_{fiber}}}{E_{{\mathrm{eff}}_{fiber}}}\right).Math.\left(1-\frac{{\rho }_{water}}{{\rho }_{{\mathrm{eff}}_{fiber}}}\right)$
is greater than 50 kg/m3/GPa. The system also includes a data acquisition unit with a processor operable to obtain strain measurement data of the wellbore from the optical fiber.

Novel chemical sensors that improve detection and quantification of CO.sub.2 are critical to ensuring safe and cost-effective monitoring of carbon storage sites. Fiber optic (FO) based chemical sensor systems are promising field-deployable systems for real-time monitoring of CO.sub.2 in geological formations for long-range distributed sensing. In this work, a mixed-matrix composite integrated FO sensor system was developed that reliably operates as a detector for gas-phase and dissolved CO.sub.2. A mixed-matrix composite sensor coating on the FO sensor comprising plasmonic nanocrystals and zeolite embedded in a polymer matrix. The mixed-matrix composite FO sensor showed excellent reversibility/stability in a high humidity environment and sensitivity to gas-phase CO.sub.2 over a large concentration range. The sensor exhibited the ability to sense CO.sub.2 in the presence of other geologically relevant gases, which is of importance for applications in geological formations. A prototype FO sensor configuration which possesses a robust sensing capability for monitoring dissolved CO.sub.2 in natural water was demonstrated. Reproducibility was confirmed over many cycles, both in a laboratory setting and in the field.