An optical fiber having a Bragg grating along a non-photosensitized grating region thereof and a pristine polymer coating around the grating region with the Bragg grating having been written through the polymer coating has a mechanical resistance that is greater than 20% of the mechanical resistance of an identical grating-free optical fiber.

An optical fiber having at least two polymer coatings, the optical fiber comprising: an optical fiber comprising a glass optical core and a glass cladding; a first polymer coating comprising a silicone polymer covering the optical fiber; and a second polymer coating covering the first polymer coating is provided.

When a grating is inscribed in a section of optical fiber through a coating of the optical fiber, using a light modulation mask to modulate the light beam that writes the grating, a fluid can be situated between the section of optical fiber and the back side of a mask component carrying the light modulation mask (e.g., on its front side) to reduce the refractive-index discontinuity encountered at the surface of the coating. In various embodiments, rather than running the fiber through a vessel containing the fluid, the fluid is run across the back side of the mask component or retained by capillary action between the fiber section and the mask component.

Disclosed herein is an optical fiber having an optically uniform coating having no physical defects in the coating greater than 100 micrometers in size over a length of 50 meters or greater.

Method of laser modifying an optical fibre to form a modified region at a target location within the fibre, comprising positioning at least a portion of an optical fibre in a laser system for modification by a laser, applying a correction to an active optical element of the laser system to modify wavefront properties of the laser to counteract an effect of aberration on laser focus, and laser modifying the optical fibre at the target location using the laser with the corrected wavefront properties to produce the modified region.

There is provided an alignment system and method for use in an ultrashort pulse duration laser-based Fiber Bragg Grating (FBG) writing system, the alignment system comprising: clamps configured to hold a coated optical fiber in a position perpendicular to a beam path of an ultrashort pulse duration laser-based FBG writing station; an optical detector; and a control system with an input from the optical detector and an output to adjust parameters of an optical source and the FBG writing station adjust a distance between the optical fiber and an optical source of the writing station based on luminescence generated in a core of the optical fiber as indicated in a signal received at the input from the optical detector.

Described herein are systems, methods, and articles of manufacture for a coated fiber modified by actinic radiation to increase back-scattering, which experiences very little back-scattering decay at a temperature and time of exposure that is sufficient to noticeably degrade the coating and/or noticeably degrade the optical fiber due to outgassing of hydrogen from the coating. In one embodiment, an optical fiber comprises a fiber length, a coating having a treated coating weight, wherein the treated coating weight is at least 25% less of an original coating weight prior to an annealing treatment, and an optical back-scatter along the fiber length greater than a Rayleigh back-scattering over the fiber length, wherein the optical back-scatter does not decrease along the fiber length by more than 3 dB after exposure to annealing treatment. A further embodiment relates to a method comprising receiving an optical fiber at an inlet of at least one heat source, the optical fiber including a coating having an original coating weight and an optical back-scatter along a fiber length and applying an annealing treatment to the optical fiber by the least one heat source at a predetermined temperature T.sub.a during a predetermined time t.sub.a, wherein the original coating weight is reduced by at least 25% to a treated coating weight during the annealing treatment, wherein the optical back-scatter does not decrease along the fiber length by more than 3 dB after the annealing treatment.

Described herein are systems, methods, and articles of manufacture for high back-scattering waveguides (e.g., optical fibers) and sensors employing high back-scattering optical fibers. Briefly described, one embodiment comprises a high back-scattering fiber, or enhanced scattering fiber or ESF, that features resistance specifications that remain intact over lengths of fiber in excess of 1 m, or preferably >100 m, or preferably >1 km, wherein the reflectivity of the ESFs may be precisely tuned within a range from ?100 dB/mm to ?70 dB/mm, and wherein the enhanced scattering may be spatially continuous or, alternatively, may be at discrete locations spaced apart by 100 microns to >10 m.

Method for creating an optical sensing fiber having a reflective structure integrally disposed therein, comprising: providing an optical fiber having a core and a cladding layer disposed in optical contact with the core, and having a polymer coating layer disposed in contact with and surrounding the cladding layer, the coating layer at least partially transparent in the wavelengths of 390-600 nm; providing a source of electromagnetic radiation having a wavelength in the range of 390-600 nm; and delivering a selected wavelength of the electromagnetic radiation through the coating layer to a selected location within the fiber core or cladding such that the delivered electromagnetic radiation alters the core or cladding to create at least one reflective structure in the core or cladding at the selected location.

When a grating is inscribed in a section of optical fiber through a coating of the optical fiber, using a light modulation mask to modulate the light beam that writes the grating, a fluid can be situated between the section of optical fiber and the back side of a mask component carrying the light modulation mask (e.g., on its front side) to reduce the refractive-index discontinuity encountered at the surface of the coating. In various embodiments, rather than running the fiber through a vessel containing the fluid, the fluid is run across the back side of the mask component or retained by capillary action between the fiber section and the mask component.