Abstract: Embodiments of the invention include a universal apparatus for incorporating intelligence into the distribution frame of an optical communication system. The communication system includes a distribution frame with one or more distribution shelves having one or more interconnection panels, and a universal operations, administration and maintenance (OA&M) apparatus attached to the distribution frame. The OA&M apparatus, which is operably connected to the interconnection panels and the distribution frame's system controller through an interface, monitors current interconnection panel connections including cross-connections and can indicate future possible cross-connections between interconnection panels. The OA&M apparatus also is useful for jumper routing, circuit administration, and other features associated with the distribution frame and its fiber connections.

Abstract: An optical fiber has a core region and a first cladding region surrounding the core. The first cladding region is doped to increase the fiber's refractive index volume. A second cladding region surrounds the first cladding region. The second cladding region is doped to reduce the fiber's cutoff wavelength, offsetting an increase in the fiber's cutoff wavelength caused by the first cladding region. An outer cladding surrounds the cutoff reduction region. In a further embodiment, the volume increasing region is doped to have a refractive index profile that is sloped to increase from the region's outer circumference towards its inner circumference. In another embodiment, the cutoff reduction region has a step refractive index profile that may have more than one section.

Abstract: An optical fiber cable includes a number of optical fiber bundles. Each bundle contains a number of optical fiber cable units, and a relatively thin skin surrounds the cable units and retains the units in a desired configuration another over the length of the bundle. Each cable unit includes a number of optical fibers, and a first outer jacket that surrounds the fibers. The bundles are protectively enclosed by a second outer jacket of the cable. In an illustrated embodiment, each cable unit has 12 fibers, each bundle contains 12 cable units, and six bundles are protectively enclosed by the second outer jacket, so that the cable contains 432 optical fibers each of which is traceable by color and/or indicia markings.

Abstract: Techniques are described for fabricating a preform from a soot body. In one described technique, a soot body is loaded into a substrate tube, and the position of the soot body is stabilized within the tube. The tube is then rotated around its longitudinal axis. Heat is applied from a heat source to the substrate tube at a first end of the soot body to cause the first end of the soot body to begin to sinter and to cause the substrate tube to begin to at least partially collapse around the sintered portion of the soot body. The heat source is then advanced along the substrate tube and the soot body to cause a progressive sintering of the soot body, and to cause a progressive, at least partial, collapse of the substrate tube around the sintered portion of the soot body.

Abstract: A fiber coating applicator includes a chamber and a cup positioned over the chamber. The cup is connected to the chamber by an entrance aperture. The chamber includes an exit aperture opposite the entrance aperture. The cup, entrance aperture, chamber, and exit aperture define a pathway for a fiber, such as an optical fiber, to be coated. The chamber further includes an input port for pumping a coating material into the chamber. The entrance aperture is dimensioned such that as a fiber travels along the pathway and coating material is pumped into the chamber, coating material travels upward through the entrance aperture around the fiber into the cup, the upward flow of coating material being restricted by the fiber and entrance aperture such that there is a hydrostatic pressure in the chamber. The exit aperture is dimensioned to shape coating material around a fiber traveling along the pathway.

Abstract: The specification describes an improved optical fiber cable wherein the cable cross section is round and contains a plurality of bundled optical fibers. The bundle may comprise randomly arranged optical fibers or optical fibers aligned in a ribbon configuration. The bundle is encased in a polymer encasement that couples mechanically to the optical fibers. In some embodiments the encasement is relatively hard, and is deliberately made to adhere to the optical fiber bundle. Consequently the encasement medium functions as an effective stress translating medium that deliberately translates stresses on the cable to the optical fibers. The cable construction of the invention is essentially void free, and provides a dry cable with water blocking capability.

Abstract: A high density panel mounting assembly has a first connector housing having first and second arrays of channels for receiving modified connectors, separated by a shelf. An adapter assembly for receiving the ferrules of the connectors has an interior wall having first and second arrays of bored projections forming sleeves for receiving the connector ferrules. The adapter assembly has a second connector housing substantially identical with the first connector housing mounted to or integral with the rear of the adapter housing for receiving individual connectors. Each of the connector housings has an array of apertures along the top and bottom surfaces for latching the connectors in place. Each of the connectors has a resilient latching arm having a distal end having a latching surface thereon which bears against the end of its corresponding aperture to latch the connector in place within the connector housing.

Abstract: The specification describes a VAD method for producing optical fiber preforms by depositing soot onto a solid core rod. The solid core rod preferably has a uniform composition, doped or undoped, suitable for the center core region of the preform. The primary cladding layer, and additional cladding layers if desired, are produced by depositing soot on the center core rod. The surface of the center core rod is treated with an etchant torch that traverses the center core rod in front of the soot deposition torch. This produces a clean interface between the core and primary cladding. This soot-on-center-core-rod method allows the production of sharp index profiles by reducing the diffusion of dopants into and out of the center core portion of the preform that occurs in soot-on-soot processes.

Abstract: A monitoring system for detection of defects in an optical fiber coating during production of the fiber has first and second beam generating means which produce planar coherent beams which cross each other at the fiber passing through the system creating one or more diffraction patterns. A first plurality of photodetectors are mounted in a mount, the front face of which is impinged by the planar diffraction pattern, and a second plurality of photodetectors is similarly mounted in position below the impinging pattern. A defect in the fiber coating, regardless of shape or orientation, will cause the pattern or patterns to be tilted or shifted upward, downward, or planarly tilted to impinge one or more of the photodiodes which, as a result, generates a signal which is applied to a comparator and control circuit.

Abstract: The specification describes a wavelength monitoring system for multiple wavelength communications systems, such as WDM systems, based on the recognition that the mechanism for spatially separating the individual wavelength bands can be achieved within the optical fiber itself. Individual wavelength bands are separated using a series of discrete gratings spaced longitudinally along the fiber core. The wavelength bands are extracted from the fiber core by converting the energy in the selected band from a core-guided mode to a radiation mode. By using a tilted grating, the light in the radiation mode is directed through the cladding and out of the fiber. Spatial resolution of the selected bands can be any desired physical length. An important implication of this is that detection can be made in the near field using inexpensive detecting apparatus.

Abstract: A connector system for terminating an optical fiber cable having a protective outer jacket. The system includes a connector plug and a crimp insert having an axial bore. A distal end of the insert is formed to be joined to a proximal end of the connector plug. A first portion of the insert bore has a diameter corresponding to an outside diameter of the cable jacket. A second portion of the insert bore has a diameter corresponding to an outer diameter of an unjacketed end of the cable. The insert deforms when crimped at axially spaced positions on its periphery, correspondonding to the first and the second portions of the insert bore. Thus, both the outer jacket and the unjacketed end of the cable are restrained from axial movement with respect to the insert and connector plug.

Abstract: The specification describes an optical filter wherein long period gratings (LPGs) are used in a new configuration to provide in-line bandpass filtering of optical signals. In the basic embodiment, two dissimilar LPGs are installed in the optical fiber transmission line. The first LPG converts light, over a broad wavelength range, being transmitted in the fundamental, or LP01, mode of the optical fiber transmission line into light in a higher order mode (HOM) of the optical fiber. The mode-converted signal, with mode LPm,n, is then coupled to a second waveguide, the second waveguide having transmission characteristics different from those of the first. The second waveguide supports propagation of light in a LPm,n mode. The mode-converted signal is then transmitted through a second LPG where the signal over a selected narrow band of wavelengths that is accepted by the second LPG is converted back to a LP01 mode.

Abstract: A fiber optic attenuating element is formed of a thermoplastic polymer having (i) a refractive index in the range of between about 1.42 and 1.47 as measured at a temperature of 230° C. and a wavelength of 1550 nm, (ii) a glass transition temperature of at least 105° C., and (iii) an intrinsic loss of less than one dB/mm at 1310 and 1550 nm. In disclosed embodiments, the polymer includes at least one monomer including fluorinated moieties and, optionally, one or more additional monomers. A main body portion of the element has a first planar contact face on a first side and a second planar contact face on a second, opposite side. The contact faces are dimensioned to couple optically with first and second optical fibers when ends of the fibers are urged against the faces by parts of an attenuator device in which the element is mounted.

Abstract: The specification describes an optical fiber drop cable with a flat configuration, corresponding to “A-drop” cable. The cable is dry, and has a conformal primary encasement that is coupled directly to the optical fiber(s). Coupling the optical fibers and the exterior surface of the cable provides unexpected benefits, reducing the tendency of the fiber cable to buckle or shrink-back, and reducing the susceptibility of the cable to fiber retraction. The drop cable comprises three in-line components encased in a conformal secondary encasement. The center component comprises the optical fiber(s) coupled to the primary encasement. Located on each side of the optical fiber system are strength members. In a preferred embodiment, dimensions of the three elements are chosen so that the diameter of the center component is less than the diameter of either strength member. This provides crush protection for the optical fiber system.

Abstract: Dynamically controlling the reaction temperature at the tip of a soot preform by controlling the flow of hydrogen gas to the core torch provides a wide latitude of control over the temperature range necessary to produce uniform composition of the preform.

Abstract: A pumped Raman fiber optic amplifier includes two optical fibers whose lengths are determined so that the fibers exhibit dispersions of substantially equal magnitude and opposite sign at the wavelength of an input light signal. The fiber having the positive dispersion has a cylindrical core, an outer cladding, and a refractive index profile with respect to the outer cladding. The core has a diameter of between 3 and 6 microns (&mgr;m) and a difference (&Dgr;n) between the index of the core and the cladding is between 0.015 and 0.035. The index profile includes a trench region adjacent the circumference of the core, and the trench region has a width of between 1 and 4 &mgr;m and a &Dgr;n of between −0.005 and −0.015. The two fibers are slope matched so that the net dispersion of the amplifier remains substantially zero over a broad wavelength interval.

Abstract: The specification describes a technique for drawing circular core multimode optical fiber using twist during draw to increase fiber bandwidth.

Abstract: The specification describes an improved optical fiber ribbon cable. The cable design addresses the problem of wrinkles in the cable coating that occur on the interior bend radius on moderate bending of the cable. The wrinkles are much smaller than the bend radius, and are, relatively speaking, microbends. These may cause microbending losses in the fibers even where the bend radius is relatively large. The cable design of the invention has a combination of three important features. The cable cross section is round. The encasement for the optical fiber stack is relatively hard, and is deliberately made to adhere to the optical fiber stack. Consequently the encasement medium functions as an effective stress translating medium that deliberately translates stresses on the cable to the optical fibers. The optical fibers function as compressive strength members to retard longitudinal strain on the cables, and thereby reduce wrinkling of the encasement.