A method of measuring a diameter of a core portion of an optical fiber preform including the core portion having a relatively high refractive index and a clad portion having a relatively low refractive index. The method includes applying parallel light to the optical fiber preform, and measuring the diameter of the core portion from an image captured by receiving the light having transmitted through the optical fiber preform.

An optical power monitor device includes a first optical fiber, including a core and a cladding surrounding the core and being at least one of an incidence-side optical fiber and a launch-side optical fiber connected to each other at a connection point, which is constituted by a curve portion and a linear portion between the curve portion and the connection point, a low refractive index layer that is provided in at least a portion of the linear portion on an outer side of the cladding and has a refractive index lower than a refractive index of the cladding, and a first optical detector that is provided at a position close to at least the curve portion.

Provided is a glass eccentricity measurement device which includes an irradiation unit that irradiates a side surface of a coated glass fiber obtained by coating the striated glass with light, and a light receiving unit that receives light scattered and/or refracted following irradiation of the side surface of the coated glass fiber therewith, and measures an eccentricity of the glass in the coated glass fiber by a pattern of brightness and darkness in the light received by the light receiving unit, in which three or more sets including the irradiation unit and a screen are provided around the coated glass fiber, and the sets are arranged respectively in directions having different angles on a circumference centered on the coated glass fiber.

An optical fiber preform including a glass material and a refractive index adjusting additive is disclosed. This preform has striae due to difference in concentration of the additive and the striae have concentric refractive index periodicity in at least a part thereof from a radial center of the preform to an outer periphery thereof. The respective striae pitches each indicating a period of the refractive index periodicity increase from the center of the preform to the outer periphery thereof.

The nondestructive determination of core size of a hollow-core photonic bandgap fiber (HC-PBF) using Fabry-Perot (FP) interference is performed with an apparatus including a tunable laser source (TLS), a 12 single-mode (SM) coupler, an SM collimator, a six-axis translation stage, an optical detector, and an oscilloscope. The light from the TLS passes through the 12 SM coupler and the SM collimator to perpendicularly enter two parallel air-SiO.sub.2 interfaces of the core of the fiber and is reflected, while the TLS is tuned from one wavelength to another. Then the reflected spectrum is guided to the optical detector, where its interference intensity is converted into voltage intensity to be displayed at the oscillator and fitted with a least-squares method to obtain the distance between the two air-SiO.sub.2 interfaces. The core size of the fiber can be obtained by rotating the fiber and repeating the procedure at multiple angular positions.

A method for inspecting an intermittent connection type optical fiber ribbon includes: accumulating one-dimensional images in a width direction of the intermittent connection type optical fiber ribbon, arranged intermittently with connection parts that connect adjacent optical fibers by repeatedly capturing images of the intermittent connection type optical fiber ribbon along the width direction while moving the intermittent connection type optical fiber ribbon in a longitudinal direction; and creating a two-dimensional image of the intermittent connection type optical fiber ribbon by aligning the one-dimensional images in a second direction orthogonal to a first direction where pixels configuring the one-dimensional image are aligned.

A method of making an optical fiber sensor device for distributed sensing includes generating a laser beam comprising a plurality of ultrafast pulses, and focusing the laser beam into a core of an optical fiber to form a nanograting structure within the core, wherein the nanograting structure includes a plurality of spaced nanograting elements each extending substantially parallel to a longitudinal axis of optical fiber. Also, an optical fiber sensor device for distributed sensing includes an optical fiber having a longitudinal axis, a core, and a nanograting structure within the core, wherein the nanograting structure includes a plurality of spaced nanograting elements each extending substantially parallel to the longitudinal axis of the optical fiber. Also, a distributed sensing method and system and an energy production system that employs such an optical fiber sensor device.

A process of in-situ detection of hollow fiber formation includes immersing a plurality of individual glass fibers in an index-matching material. The index-matching material has a first refractive index that substantially matches a second refractive index of the glass fibers. The process also includes exposing the individual glass fibers to a light source during immersion in the index-matching material. The process further includes utilizing one or more optical components to collect optical data for the individual glass fibers during immersion in the index-matching material. The process also includes determining, based on the optical data, that a particular glass fiber of the plurality of individual glass fibers includes a hollow fiber.

A method of making an optical fiber sensor device for distributed sensing includes generating a laser beam comprising a plurality of ultrafast pulses, and focusing the laser beam into a core of an optical fiber to form a nanograting structure within the core, wherein the nanograting structure includes a plurality of spaced nanograting elements each extending substantially parallel to a longitudinal axis of optical fiber. Also, an optical fiber sensor device for distributed sensing includes an optical fiber having a longitudinal axis, a core, and a nanograting structure within the core, wherein the nanograting structure includes a plurality of spaced nanograting elements each extending substantially parallel to the longitudinal axis of the optical fiber. Also, a distributed sensing method and system and an energy production system that employs such an optical fiber sensor device.

Examples disclosed herein illustrate systems and methods to determine and evaluate the quality of mechanical splices of optical fibers using insertion loss estimation. In at least some of the disclosed systems and methods, an optical fiber termination system may include a reference fiber coupling a light source and a stub fiber of a fiber optic connector, a digital camera sensor and lens to capture images of scattered light emanating from a portion of the fiber optic connector and a portion of the reference fiber both in a field of view (FOV) of the digital camera sensor, and a processor. The processor may analyze digital images of scatter light emitted from at least a portion of the fiber optic connector and the reference fiber to estimate insertion loss at the fiber optic connector.