Abstract: dispersion and dispersion slope compensating optical fiber includes a segmented core and a cladding layer wherein the refractive index profile is selected to provide a dispersion having a maximum deviation of less than 7 ps/nm-km over a wavelength band from 1550 nm to 1610 nm. According to a further embodiment of the invention, a dispersion compensating optical fiber is provided having a refractive index profile with a central core segment having a positive relative refractive index; a depressed moat segment on a periphery of the central core segment having a relative refractive index that is more negative than −1.2%; and an annular ring segment outward from the depressed moat segment having a relative refractive index that is greater than 1.2%.

Abstract: Disclosed is a dispersion compensating optical fiber that includes a core surrounded by a cladding layer of refractive index &Dgr;c. The core includes at least three radially adjacent regions, a central core region having &Dgr;1, a moat region having a refractive index &Dgr;2 and an annular ring region having a refractive index &Dgr;3, such that &Dgr;1>&Dgr;3>&Dgr;c>&Dgr;2. The fiber exhibits a dispersion at 1550 which is less than −30 ps/nm/km, and a &kgr; value obtained by dividing the dispersion value by the dispersion slope which is between 40 and 100.

Abstract: The present invention relates to a dispersion compensating optical fiber (“DC fiber”) having a segmented core of at least three segments and having a negative total dispersion and negative dispersion slope in the L-band. The index profile of the segmented core is selected to provide an optical fiber having properties suitable for a high performance communication system operating in the L-band wavelength band, i.e., between about 1570 nm to 1620 nm. The DC fiber according to the invention exhibits total dispersion at 1595 nm of between −70 and −225 ps/km/nm and dispersion slope more negative than −0.7 ps/km/nm2. The DC fiber may be optically connected to a non-zero dispersion shifted fiber in the system to compensate for dispersion and dispersion slope thereof.

Abstract: The present invention relates to a dispersion compensating optical fiber (“DC fiber”) having a segmented core of at least three segments and having a negative total dispersion and negative dispersion slope in the L-band. The index profile of the segmented core is selected to provide an optical fiber having properties suitable for a high performance communication system operating in the L-band wavelength band, i.e., between about 1570 nm to 1620 nm. The DC fiber according to the invention exhibits total dispersion at 1595 nm of between −95 and −225 ps/km/nm and dispersion slope more negative than −1.0 ps/km/nm2. The DC fiber may be optically connected to a non-zero dispersion shifted fiber in the system to compensate for dispersion and dispersion slope thereof.

Abstract: A method for manufacturing optical fiber with enhanced photosensitivity comprising the step of: forming a molten layer of glass and drawing a fiber from the molten layer of glass at a temperature of between about 1900° C. and 1995° C. Draw tension can be adjusted to attain the desired draw speed.

Abstract: Disclosed is a single mode optical waveguide fiber having a low cut off wavelength, and mode field diameter and bend resistance similar to step index single mode optical waveguide fiber designed for use at 1310 nm. By including a clad region of raised refractive index spaced apart from the core region of the single mode optical waveguide fiber, the cut off wavelength can be reduced to 850 nm. The single mode optical waveguide fiber in accord with the invention may also have a core region having a reduced refractive index on centerline surrounded by a region of higher refractive index and a clad region which is substantially uniform. The single mode optical waveguide fiber is thus ideally suited for use with the low cost, reliable VCSEL operating at 850 nm, a Fabry-Perot laser operating at 1310 nm, or a distributed feedback laser operating at 1550 nm thereby enabling low cost, easily installed, home access portions of the broadband telecommunications system.

Abstract: Disclosed is a dispersion compensating optical fiber that includes a core surrounded by a cladding layer of refractive index &Dgr;c. The core includes at least three radially adjacent regions, a central core region having &Dgr;1, a moat region having a refractive index &Dgr;2 and an annular ring region having a refractive index &Dgr;3, such that &Dgr;1 >&Dgr;3>&Dgr;c>&Dgr;2. The fiber exhibits a dispersion at 1550 which is less than −30 ps/nm/km, and a &kgr; value obtained by dividing the dispersion value by the dispersion slope which is between 40 and 100.

Abstract: A dispersion compensating module, mode converter, coupler and dispersion compensated optical fiber therein. The dispersion compensating fiber has a plurality of core segments, the refractive index profile being selected to exhibit properties such that an LP02 mode at 1550 nm may be propagated a distance (generally 0.5-3.0 km), upon conversion to LP02, to compensate for dispersion of a length of transmission waveguide preferably greater than 25 km propagating in an LP01 mode. In another embodiment, the dispersion compensating module has a mode converter having a reflective fiber grating for converting a first to a second mode interconnected to a dispersion compensated fiber propagating in the second mode. The mode converter has a coupler adapted to operatively couple light propagating in a first mode from a first fiber into a second, and a reflective fiber grating operatively coupled to the second fiber; the grating being capable of converting light from the first into the second mode.

Abstract: The present invention discloses novel methods for fabricating optical fiber glass preforms which may contain alumina, germania, erbium, or other rare earth metals as dopants. Doping with a higher concentration of alumina enhances the solubility of the erbium, or other rare earth, dopant within the glass and the resultant optical properties of the fiber. However, the addition of an alumina dopant can cause processing difficulties due to the formation of inclusions, such as gas bubble, seeds or crystallite formation, within the glass preform or glass cane. The present invention overcomes these processing difficulties and produces glass preforms or canes that are inclusion-free.

Abstract: Disclosed is a total dispersion and total dispersion slope compensating optical waveguide fiber. The refractive index profile of the compensating waveguide fiber includes a core region having a central segment and two surrounding annular segments. In an embodiment of the compensating waveguide fiber, a first clad layer adjacent the core region has a refractive index lower than that of a second clad layer adjacent the first clad layer. The optical waveguide fiber in accord with the invention has negative total dispersion and negative total dispersion slope over the operating window of the fiber to be compensated. The invention includes a compensated optical waveguide fiber span which includes a high performance waveguide fiber and a compensating waveguide fiber in accord with the invention.

Abstract: The present invention includes a method of making a preform for an enhanced photosensitive fiber comprising depositing successive layers of optical material the inside a tube using modified chemical vapor deposition, and collapsing the layers of optical material in a reducing atmosphere with a positive pressure. The present invention also includes a method of making an enhanced photosensitive fiber comprising making a preform using modified chemical vapor deposition wherein the preform is collapsed in a reducing atmosphere with a positive pressure and drawing the preform into a fiber.

Abstract: A dispersion compensating module, mode converter, coupler and dispersion compensated optical fiber therein. The dispersion compensating fiber has a plurality of core segments, the refractive index profile being selected to exhibit properties such that an LP02 mode at 1550 nm may be propagated a distance (generally 0.5-3.0 km), upon conversion to LP02, to compensate for dispersion of a length of transmission waveguide preferably greater than 25 km propagating in an LP01 mode. In another embodiment, the dispersion compensating module has a mode converter having a reflective fiber grating for converting a first to a second mode interconnected to a dispersion compensated fiber propagating in the second mode. The mode converter has a coupler adapted to operatively couple light propagating in a first mode from a first fiber into a second, and a reflective fiber grating operatively coupled to the second fiber; the grating being capable of converting light from the first into the second mode.

Abstract: Disclosed is a dispersion compensating optical fiber that includes a core surrounded by a cladding layer of refractive index &Dgr;c. The core includes at least three radially adjacent regions, a central core region having &Dgr;1, a moat region having a refractive index &Dgr;2 and an annular ring region having a refractive index &Dgr;3, such that &Dgr;1>&Dgr;3>&Dgr;c>&Dgr;2. The fiber exhibits a dispersion slope which is less than −1.0 ps/nm2/km over the wavelength range 1525 to 1565, a dispersion at 1550 which is less than −30 ps/mn/km, and a &kgr; value obtained by dividing the dispersion value by the dispersion slope which is greater than 35 and preferably between 40 and 100.

Abstract: A method of making a glass article such as an optical waveguide preform is disclosed. The method comprises drawing a rod in at least two steps. In the first step an elongated, consolidated preform having an aperture therethrough is drawn to a reduced diameter preform. The second step involves drawing the reduced diameter preform into a rod, preferably at a lower temperature than the first step. The method substantially reduces the formation of inclusions in the glass article during drawing.

Abstract: An optical waveguiding fiber has a photosensitive core and a cladding that includes a photosensitive inner cladding region adjacent the core and an outer cladding region. The inner cladding region and the outer cladding region have substantially equal indices of refraction. The photosensitivity of the inner cladding region is sufficient to cause a modulation of the index of refraction of the inner cladding when exposed to ultraviolet light. In another aspect of the invention, the optical fiber includes a grating in the core, which extends radially into the inner cladding region. The core and the inner cladding region of the optical fiber are doped with concentrations of Ge and B sufficient to impart photosensitivity to the inner cladding region, and to result in an index of refraction in the inner cladding region substantially equal to the index of refraction of the outer cladding region.

Abstract: Disclosed is a dispersion compensating optical fiber that includes a core surrounded by a cladding layer of refractive index &Dgr;c. The core includes at least three radially adjacent regions, a central core region having &Dgr;1, a moat region having a refractive index &Dgr;2 and an annular ring region having a refractive index &Dgr;3, such that &Dgr;1 >&Dgr;3>&Dgr;c>&Dgr;2. The fiber exhibits a dispersion slope which is less than −1.0 ps/nm2/km over the wavelength range 1525 to 1565, a dispersion at 1550 which is less than −30 ps/mn/km, and a &kgr; value obtained by dividing the dispersion value by the dispersion slope which is greater than 35 and preferably between 40 and 100.