Abstract: The invention disclosed is an optical fiber which includes a central core glass region with a first refractive index profile. The fiber includes a second core glass region adjacent to and surrounding said central region, said second region having a thickness that varies along an axial direction of said second region and having a second refractive index profile that differs from said first profile. Additionally, the invention includes an optical fiber preform that can be drawn into the above fiber. The invention also includes the method of making the above describe optical fiber. Furthermore, the invention may also be practiced to make an optical fiber preform in accordance with the aforementioned invention. The aforementioned fiber and preform is particularly useful as a dispersion managed fiber or dispersion managed preform respectively.

Abstract: An apparatus and method for sealing the top of an optical waveguide draw furnace is disclosed. The apparatus includes an assembly constructed and arranged to removably cover the top of the draw furnace while mating with the downfeed handle. The apparatus includes an elongated sleeve having a base and a sealing mechanism positioned on the sleeve at a location remote from the base. The sleeve defines a chamber for receiving the downfeed handle, and the sealing mechanism is arranged with respect to the sleeve to mate with the downfeed handle received in the chamber. In one aspect of the invention, the apparatus further includes an inert gas purge for providing an inert atmosphere within the chamber. A method of sealing the top of an optical waveguide draw furnace is also disclosed.

Abstract: Atomizing devices are provided that form droplets through the Rayleigh breakup mechanism. Various embodiments include one or more of the following features. Liquid orifices form jets of liquid that form droplets. Gas orifices provide gas coflow that inhibits coalescence of the droplets. The liquid orifices can have non-circular cross-sectional shapes to promote Rayleigh breakup. Fluidic oscillators can also be provided to promote Rayleigh breakup. Supply networks are provided to supply gas and liquid to the gas and liquid orifices, respectively.

Abstract: The present invention is directed to a silica forming feedstock and a method of making optical waveguides and optical waveguide preforms. The feedstock for use in the manufacturing of germanium doped silica glass products includes a siloxane and a germanium dopant component such as germanium alkoxide. The invention further relates to the manufacturing of optical waveguides and optical waveguide preforms using a fluid feedstock which includes a siloxane and germanium dopant component, preferably germanium alkoxide.

Abstract: A method and apparatus for determining an identity of at least one constituent on a soot that is deposited on a substrate is disclosed. The method includes the steps of sending a pulse of energy toward the substrate, focusing the energy to a predetermined point on the substrate to thereby generate a plasma on the substrate and to create at least one photon, detecting the photon using an analysis element, and identifying the constituent in the soot. The method may also include the step of determining the concentration of the constituent. Furthermore, the method may be used to determine the identity and concentration of at least one reactant in a flame of a burner or a reactant stream.

Abstract: A method for making silicon oxynitride comprising providing a vaporous gas stream of a compound selected from the group consisting of silazanes and siloxazanes. An enclosed, heated reaction site is also provided. The vaporous gas stream is delivered to the enclosed, heated reaction site in which the levels of oxygen are strictly controlled to promote the formation of silicon oxynitride particles.

Abstract: The present invention relates to a composition for coating optical fibers which contains an oligomer capable of being polymerized, a monomer suitable to control the viscosity of the composition, and an adhesion promoter which includes a compound containing a cyclic structure interposed between at least two reactive silanes which are independently an alkoxysilane or a halosilane. Another composition of the present invention includes an oligomer capable of being polymerized, a monomer suitable to control the viscosity of the composition, an adhesion promoter which includes a compound containing a reactive silane group, and a carrier. The present invention also relates to optical fibers and methods of making such optical fibers using the compositions of the present invention.

Abstract: Optical fiber is provided with a periodically reversing spin while the fiber is pulled through a melt zone. A cooled region of the fiber downstream from the melt zone passes between a pair of opposed elements. The opposed elements are moved so that surface regions engaging the fiber move in opposite lateral directions relative to one another, thus spinning the fiber about its axis. The lateral movement of the engaged surface portions is periodically reversed to reverse the spin direction. The opposed elements may include belts or rollers, which can be tilted to orientations oblique to the longitudinal direction of the fiber.

Abstract: The present invention relates to a composition for coating optical fibers which contains an oligomer capable of being polymerized, a monomer suitable to control the viscosity of the composition, and an adhesion promoter which includes a compound containing a cyclic structure interposed between at least two reactive silanes which are independently an alkoxysilane or a halosilane. Another composition of the present invention includes an oligomer capable of being polymerized, a monomer suitable to control the viscosity of the composition, an adhesion promoter which includes a compound containing a reactive silane group, and a carrier. The present invention also relates to optical fibers and methods of making such optical fibers using the compositions of the present invention.

Abstract: The invention is a method of making an optical fiber or cane (600) that has optical properties that vary axially. Core glass (100) and clad glass (200) are fed into a furnace to form the cane or fiber. The velocities of the feeding of the clad and core are controlled so that the total combined mass per unit time is constant. The diameter of the core (604) varies along the length of the fiber or cane in accordance with the control of the velocities. The variance in the core diameter results in the variance of the axial optical properties of the fiber or cane.

Abstract: The invention includes an optical waveguide whipping end cutting apparatus. The apparatus includes an active cutting element. The element is positioned to cut a segment from a whipping end of an optical fiber, while the fiber is being wound onto a rotating spool. This apparatus will prevent fiber whip. The invention also includes a method of cutting a whipping end from an optical fiber. The method includes removing a segment of the end of the fiber with an active cutting element. A method of cutting an optical fiber while winding the fiber onto a storage spool is further discussed. The fiber has a whipping end and a wound segment. The method includes separating the whipping end of the fiber from the wound segment with an active cutting element. Furthermore, the invention includes a method of reducing fiber whip damage to fiber wound on a spool. This includes engaging an active cutting element on the fiber being wound onto the spool, and removing a whipping end from the fiber.

Abstract: A sintered dense glass, alumina-doped optical fiber preform is stretched and is then heated to a temperature of 1490-1495° C. to remove bubbles without causing crystallization. Thereafter, the stretched glass body is either drawn directly into an optical fiber or overclad and then drawn into a fiber.

Abstract: The disclosed invention is a rotationally symmetrical resistance furnace heating element. The heating element has at least two ends. A respective cooling element is disposed in communication with each end. The heating element includes at least first and second high current density sections. The high current density sections are axially separated by at least one low current density section. The high current density sections have a smaller diameter than the low current density section. The invention also includes a multiple crucible method of drawing an optical fiber from the draw furnace described above. The method includes the step of heating an entire body of raw materials in a hot zone in the furnace.

Abstract: An apparatus and method for sealing the bottom of an optical waveguide draw furnace is disclosed. The apparatus includes an assembly constructed and arranged to mate with the bottom of the draw furnace to form a seal, and a leak detection system communicating with the assembly to signal the forming of a proper or an improper seal. The covering plate of the assembly is selectively seated on the sealing plate of the draw furnace to form the seal, and an inert gas is delivered between the covering plate and the bottom of the draw furnace. The flow of the inert gas is detected to determine if the seal has been properly formed. An assembly including a covering plate having at least two radially spaced gaskets circumferentially positioned on the top surface of the covering plate for engagement with the sealing plate at the bottom of the draw furnace, and a method for sealing the bottom of a draw furnace are also disclosed.

Abstract: The invention provides improved methods for reducing polarization mode dispersion (PMD) in single mode fiber by spinning the fiber during the drawing process in accordance with a spin function having sufficient harmonic content to achieve low levels of PMD for commercial fibers for which the beat lengths of the fibers, including the beat lengths of different portions of the fibers, are variable and thus not readily known in advance. The spin functions of the invention take advantage of certain resonances in energy transfer between polarization modes to achieve substantial reductions in PMD for a wide range of beat lengths. Examples of suitable spin functions include frequency-modulated and amplitude-modulated sine waves.

Abstract: A method is disclosed for recovering germanium from a gaseous mixture which includes a germanium-containing compound in vapor or particulate form, acid in vapor form, and water vapor. The gaseous mixture is contacted with a liquid containing water under conditions effective to dissolve the germanium-containing compound in the liquid. The acidity of the resulting liquid mixture is increased under conditions effective to vaporize the germanium-containing compound. The vaporized germanium-containing compound is contacted with one or more aqueous solutions under conditions effective to dissolve and precipitate the germanium-containing compound in at least one of the one or more aqueous solutions, and the resulting precipitate is separated from the at least one of the one or more aqueous solutions. The methods described herein are particularly well suited for recovering germanium from the waste gases produced during optical waveguide manufacturing processes.

Abstract: The present invention is directed to a method of enhancing the photosensitivity of an optical waveguide and an optical waveguide having persistent UV photosensitivity following out diffusion of a loading gas such as H2 or D2. The optical waveguide is loaded with a gas such as H2 or D2 to form an associated baseline refractive index. At least a portion of the loaded optical waveguide is exposed to UV radiation to induce a change in the baseline refractive index and the waveguide is annealed to diffuse the gas from the loaded optical waveguide and to stabilize the change in refractive index. Following annealing the optical waveguide retains a UV photosensitivity sufficient to produce significant refractive index changes relative to the induced change in baseline refractive index. The method of the present invention is particularly well suited for designing and fabricating grating devices, tuning grating strength and wavelength, and for providing accurate spatial control of waveguide photosensitivity.

Abstract: Atomizing devices are provided that form droplets through the Rayleigh breakup mechanism. Various embodiments include one or more of the following features. Liquid orifices form jets of liquid that form droplets. Gas orifices provide gas coflow that inhibits coalescence of the droplets. The liquid orifices can have non-circular cross-sectional shapes to promote Rayleigh breakup. Fluidic oscillators can also be provided to promote Rayleigh breakup. Supply networks are provided to supply gas and liquid to the gas and liquid orifices, respectively.

Abstract: An optical-transmission system includes a split-gain amplifier, a first connector device, a second connector device, and a signal-modifying device. The split-gain amplifier has a first gain stage optically connected to a first set of at least two waveguide paths and a second gain stage optically connected to a second set of at least two waveguide paths. The first connector device optically connects the at least two waveguide paths of the first set to a first combined-waveguide path. The second connector device optically connects the at least two waveguide paths of the second set to a second combined-waveguide path. The signal-modifying device is optically connected to the first and second combined-waveguide paths.

Abstract: An apparatus and method for reducing or preventing fiber entry whip as the loose end of a fiber being wound on a spool enters a fiber winding device. A fiber winding device comprises a spool winder entrance, a winding spool and a fiber whip shield substantially surrounding the winding spool. A fiber entry whip reducer positioned in front of the fiber winding device comprises at least one pulley and a guide channel including a straight entry section and a curved section leading to the fiber winding device. The guide channel is formed and positioned such that the loose end of the fiber is maintained against the guide channel by centrifugal force imparted onto the fiber by the curvature of the channel and forward motion of the fiber produced by the rotating spool, thereby producing a trajectory such that the loose end of the fiber enters the fiber winding device and is maintained against the whip shield.