Abstract: An apparatus for estimating a shape, the apparatus including: an optical fiber configured to conform to the shape and having a first core offset from a centerline of the optical fiber, the first core having an optical characteristic configured to change due to a change in shape of the optical fiber wherein a change in the optical characteristic is used to estimate the shape. A method for estimating a shape is also disclosed.

Abstract: An optical fiber seal includes: an annular layer bonded to an outer glass layer of a length of an optical fiber; and a glass sealing layer bonded to an outer surface of the annular layer and configured to withstand conditions in a downhole environment, the glass sealing layer configured to hermetically seal the length of the optical fiber.

Abstract: A method, system and apparatus for obtaining a parameter of interest relating to a wellbore is disclosed. A fiber optic cable having a plurality of sensors is disposed in the wellbore, wherein the plurality of sensors have reflectivity values configured to provide improved signal-to-noise ratio compared to signal-to-noise ratio of a plurality of sensors having substantially same reflectivity values. Light is propagated into the fiber optic cable from a light source and signals are received at a detector from the plurality of sensors in response to interaction of the propagated light with the plurality of sensors. A processor may be used to obtain the parameter of interest from the received signals. The fiber optic cable may be coupled to a member in the wellbore, wherein the parameter of interest is related to the member.

Abstract: A fiber optic cable includes: a first elongated body, the first elongated body having a longitudinal axis; an elongated sleeve disposed coaxially with the first elongated body, the elongated sleeve including a plurality of second elongated bodies wrapped around an exterior surface of the first elongated body; and at least one elongated fiber optic component disposed inside of and coaxially with at least one of the first elongated body and a second elongated body.

Abstract: An apparatus for estimating a property includes a hollow core tube and an input light guide disposed at least partially within hollow core tube. The apparatus also includes a second gap disposed within the hollow core tube and separated from the input light guide by an air gap width. The second gap is formed of a first solid material and has a second gap width. The apparatus also includes a third gap disposed at least partially within the hollow core tube and being further from the input light guide than the second gap. The third gap is formed of a second solid material and has a third gap width.

Abstract: An apparatus for estimating a property, the apparatus includes: a hollow core tube having a first opening and a second opening; a first optical waveguide disposed within the first opening; and a second optical waveguide disposed within the second opening and spaced a distance from the first optical waveguide, the distance being related to the property; wherein a portion of at least one of the optical waveguides within the tube is perimetrically isolated from the tube.

Abstract: An apparatus for estimating a shape, the apparatus including: an optical fiber configured to conform to the shape and having a first core offset from a centerline of the optical fiber, the first core having an optical characteristic configured to change due to a change in shape of the optical fiber wherein a change in the optical characteristic is used to estimate the shape. A method for estimating a shape is also disclosed.

Abstract: The present invention concerns an optical fiber 10 comprising a substantially pure silica glass core 12, a concentric tin-doped core/cladding interface region 14, and a concentric fluorine-doped depressed cladding layer 16. The tin-doped core/cladding interface region 14 comprises a low concentration gradient of tin dioxide, which advantageously results in a de minimis refractive index change, resistance to hydrogen incursion, and thermal stability of any fiber Bragg gratings written into the interface region 14.

Abstract: A multi-core distributed temperature sensing optical fiber is described, wherein the arrangement and construction of at least two cores provides a spectral attenuation corrected (e.g., corrected for hydrogen and/or stress on the fiber) temperature measurement.

Abstract: A multi-core optical fiber sensor is described, which sensor includes an optical fiber having at least two cores, wherein the cores have collocated measurement portions, for example in-fiber interferometers or Bragg grating portions. In an exemplary embodiment, the fiber is provided with collocated measurement portions during fiberization to eliminate drift factors and to provide temperature corrected parameter measurement capabilities.

Abstract: A multi-core distributed temperature sensing optical fiber is described, wherein the arrangement and construction of at least two cores provides a spectral attenuation corrected (e.g., corrected for hydrogen and/or stress on the fiber) temperature measurement.

Abstract: A preform for a low loss fiber optic cable and method and apparatus for fabricating such a preform is provided. The method includes providing AlCl3 and CVD precursors and locally doping CaCl3. Alkali and/or alkaline earth fluxing agents can be introduced. The alkali and/or alkaline earths are doped along with the aluminum into the silica glass core.

Abstract: A preform for a low loss fiber optic cable and method and apparatus for fabricating such a preform is provided. The method includes providing AlCl3 and CVD precursors and locally doping CaCl3. Alkali and/or alkaline earth fluxing agents can be introduced. The alkali and/or alkaline earths are doped along with the aluminum into the silica glass core.

Abstract: A preform for a low loss fiber optic cable and method and apparatus for fabricating such a preform is provided. The method includes providing AlCl3 and CVD precursors and locally doping CaCl3. Alkali and/or alkaline earth fluxing agents can be introduced. The alkali and/or alkaline earths are doped along with the aluminum into the silica glass core.