Abstract: An optical fiber, comprising: (i) a rare earth doped silica based elongated core with a first refractive index (n1) with an aspect ratio of 1:5 to 1; (ii) a silica based moat abutting and at least substantially surrounding the core, the moat having a refractive index n2, wherein n2<n1; (iii) a silica based inner cladding surrounding the moat, the inner cladding having a third refractive index (n3), wherein n1>n3; and n3>n2; (iv) a silica based outer cladding surrounding said inner cladding, the outer cladding having a fourth refractive index (n4), such that n4<n3; the optical fiber exhibits single polarization at the operating wavelength band.

Abstract: An optical fiber, comprising: a central core having a maximum dimension (A) greater than a minimum dimension (B) and a substantially elliptical shape, the fiber having at least one air hole positioned each opposite side of the central core wherein the optical fiber exhibits (i) single polarization propagation within a single polarization band and (ii) polarization maintaining property, such that the fiber beat length normalized at 1550 nm is less than 10 mm; and the polarization maintaining band is situated within wavelengths which are (a) adjacent to and below the single polarization band; and (b) above the higher order mode cutoff wavelength.

Abstract: Disclosed is an optical fiber (20) having a centermost laterally-elongated core (30) having a short dimension (a), a long dimension (b) and a first refractive index (n1), a moat (40) surrounding the central laterally-elongated core, the moat (40) having a second refractive index (n2), an outer dimension (c) and an outer dimension (d), and a cladding (50) surrounding the moat (40), the cladding (50) having a third refractive index (n3), wherein n1>n3>n2, a ratio of b/a is between 1.5 and 5.0, and a ratio of d/a is between 2.0 and 7.0. The fiber exhibits polarization maintaining properties in a PMB situated below (i.e., at shorter wavelength than SPB), such that beat length normalized to 1550 nm wavelength is preferably less than 10 mm. The fiber (20) may be coupled to optical components in apparatus where single polarization or polarization maintaining properties are desired.

Abstract: An optical fiber comprising: (i) a silica based, rare earth doped core having a first index of refraction n1; (ii) a silica based inner cladding surrounding the core having a second index of refraction n2, such that n1>n2; (iii) a silica based outer cladding surrounding the inner cladding having a third index of refraction n3 such that n2>n3, wherein inner cladding diameter is at least 125 ?m.

Abstract: A method and apparatus for providing a uniform coating thickness along an axial direction within an internal portion of a substrate tube is disclosed. A gas delivery unit is configured to coat the internal portion of the substrate tube. The gas delivery unit includes an insert. At least one of an inner diameter of the insert, a length of the insert, a gap between the insert and the substrate tube, and a flow of the gas mixture delivered to the substrate tube is configured to provide the uniform coating thickness along the axial direction.

Abstract: A method and apparatus for forming a glass article such as an optical fiber having a substantially matching viscosity across an interface associated with a first section and a second section of the optical fiber is disclosed herein. The first section has a first halogen concentration and the second section has a second halogen concentration. At least one of a partial pressure of the second halogen provided to a substrate tube and a temperature of the substrate tube is configured to affect the concentration of the second halogen in the second section. Optical fiber embodiments are also included.

Abstract: This invention relates to a method of preparing an optical fiber preform with the preform having a uniform refractive index profile for the deposited oxide material that ultimately forms the optical fiber core. One embodiment of the invention relates to a process for preparing an optical fiber preform comprising the steps of etching a substrate a first time to remove a portion of a deposited oxide material from the preform by using a gas comprising an etchant gas containing fluorine at a sufficient temperature and gas concentration to create a fluorine contamination layer in the remaining deposited oxide material; and etching the preform a second time using a gas comprising an etchant gas containing fluorine at a sufficient temperature and gas concentration to remove the fluorine contamination layer without any substantial further fluorine contamination of the remaining deposited oxide material. Further embodiments relate to similar processes.

Abstract: A dispersion compensating fiber that includes a segmented core having a refractive index profile with a core segment having a &Dgr;1% greater than 2.0%, a clad layer surrounding and in contact with the core and having a refractive index profile, wherein the refractive index profiles are selected to provide a total dispersion at a wavelength of about 1550 nm of less than or equal to about −177 ps/nm/km, and a total dispersion slope at a wavelength of about 1550 nm of less than or equal to about −2.0 ps/nm2/km. The refractive index profiles are further selected to provide a kappa value, defined as the total dispersion at 1550 nm divided by the dispersion slope at 1550 nm, of greater than or equal to about 67 nm.

Abstract: This invention relates to a method of preparing an optical fiber preform with the preform having a uniform refractive index profile for the deposited oxide material that ultimately forms the optical fiber core. One embodiment of the invention relates to a process for preparing an optical fiber preform comprising the steps of etching a substrate a first time to remove a portion of a deposited oxide material from the preform by using a gas comprising an etchant gas containing fluorine at a sufficient temperature and gas concentration to create a fluorine contamination layer in the remaining deposited oxide material; and etching the preform a second time using a gas comprising an etchant gas containing fluorine at a sufficient temperature and gas concentration to remove the fluorine contamination layer without any substantial further fluorine contamination of the remaining deposited oxide material. Further embodiments relate to similar processes.

Abstract: A method and apparatus for providing a uniform coating thickness along an axial direction within an internal portion of a substrate tube is disclosed. A gas delivery unit is configured to coat the internal portion of the substrate tube. The gas delivery unit includes an insert. At least one of an inner diameter of the insert, a length of the insert, a gap between the insert and the substrate tube, and a flow of the gas mixture delivered to the substrate tube is configured to provide the uniform coating thickness along the axial direction.

Abstract: A method and apparatus for forming a glass article such as an optical fiber having a substantially matching viscosity across an interface associated with a first section and a second section of the optical fiber is disclosed herein. The first section has a first halogen concentration and the second section has a second halogen concentration. At least one of a partial pressure of the second halogen provided to a substrate tube and a temperature of the substrate tube is configured to affect the concentration of the second halogen in the second section. Optical fiber embodiments are also included.