Abstract: A tube take-up apparatus is provided to handle a length of freshly extruded tube. The apparatus includes an elongated housing in which a pair of parallel, spaced-apart rollers extend lengthwise in a position just below the extruded tubing. The housing is removably mounted on an elongated supporting fin which is secured to the extruder at its near end, extends upwardly between the two rollers and substantially along the entire length of the housing, and is, in turn, supported on a fixed pedestal at its remote end. After the full length of tubing has been extruded, the housing and rollers as a unit are lifted with the tube from the supporting fin and replaced by an empty housing, to extrude the next tube, while the full housing is carried away to a dryer.

Abstract: The specification describes a technique for evaluating optical fiber splices. The essence of the technique involves detecting thermal power emanating from the fiber splice as the result of absorption of the light carried by the fiber. The technique is particularly suited for cladding pumped lasers wherein the splicing operation may introduce excessive absorption of pump laser radiation and excessive heating at the splice locale.

Abstract: An optical fiber connector adapter has a sensing mechanism for determining when the adapter has a connector plug therein and when the adapter is vacant or empty. The sensing mechanism creates an indication of the state of the adapter which is transmitted to a control circuit. The control circuit responds to the indication by activating or de-activating a laser, for example, which applies optical energy to the adapter. The laser is deactivated when the adapter has no connector plug therein and is activated when there is a connector plug in place in the adapter. In two of the embodiments of the invention, the sensing mechanism signals the impending insertion or withdrawal of the connector plug relative to the adapter.

Abstract: Techniques and systems are described for reducing splice loss in an optical fiber transmission line. One described technique includes splicing together at a splice point a first fiber having a first modefield diameter to a second fiber having a second modefield diameter larger than the first modefield diameter. The splice point is heated to a core expansion temperature to cause a controlled thermal diffusion of core dopant in the first fiber in order to reduce modefield mismatch between the first and second fibers. Splice loss is then reduced by heating the splice point to a differential diffusion temperature to cause a controlled diffusion of a cladding dopant in the first fiber, while maintaining the expanded core.

Abstract: The specification describes a water blocking tape for an optical fiber cable wherein the optical fibers in the cable are wrapped with a synthetic fibrous non-woven tape coated with a superabsorbent polymer powder coating. The particles in the powder are ultra-fine, i.e. have less than 10% weight fraction over 250 microns in diameter, and less than 2% weight fraction over 300 microns in diameter. Controlling the particle size within this small range is found to reduce microbending losses in the optical fiber.

Abstract: A Raman amplified dispersion compensation module has a first dispersion compensating fiber (DCF) with an input end and an output end. The first DCF has a known Raman gain coefficient (gr(&lgr;)), Raman effective fiber area (AReff), and dispersion characteristic. An input end of a second DCF is arranged to receive light signals from the output end of the first DCF. The second DCF has a known gain coefficient and effective area, and a dispersion characteristic selected to cooperate with that of the first DCF to produce a desired total module dispersion. The lengths of the DCFs are selected in a manner that optimizes the overall module gain.

Abstract: An optical fiber connection device is disclosed that allows for in situ variable attenuation of a signal transmitted between two optical fibers. The connection device comprises an attenuator element fabricated with an inherently compliant, elastomeric material, preferably a silicone elastomer. The elastomeric properties of the attenuator element allow for varying the thickness of the attenuator element and thereby changing the level of attenuation in situ. Silicone elastomers are preferred for fabricating the attenuator element as applicants have discovered they may be index-matched to optical transmission fibers, have a high creep modulus, exhibit relatively constant mechanical properties over a broad range of temperatures, and are reliable upon exposure to varied environmental conditions.

Abstract: Applicants have discovered that glass optical waveguides subject to hydrogen-induced loss increases can be passivated by treating the glass with deuterium. The deuterium-treated glass not only exhibits a lower rate of loss increase when later exposed to environments containing H2, but also retains high transmission of light in the 1.55 and 1.31 micrometer wavelength regions immediately after the deuterium heat treatment. The method applies to Er-doped fiber, transmission fiber and planar waveguides. Under some circumstances, hydrogen can be substituted for deuterium.

Abstract: Finishing the end of a plastic optical fiber by a device having a semi-rigid or rigid base, a solvent liner for absorbing and holding a solvent, and a re-attachable pull-off cover for keeping the solvent from evaporating when not in use. To polish the end of a plastic optical fiber, the cover is peeled off, the end of the optical fiber is contacted with the solvent liner such that solvent is transferred to the end of the optical fiber, the cover may be reapplied (using a pressure sensitive adhesive integral to either the bottom of the peel-off cover or the top of the liner), the excessive solvent, if any, is removed by using an appropriate swab, and the end of the plastic optical fiber is allowed to return to its normal state. The solvent temporarily dissolves the surface layer of the end of the optical fiber. The resulting surface tension automatically polishes the end of the optical fiber.

Abstract: The present invention is a flexible plastic membrane which supports embedded components such as light emitting diodes and plastic pressure switches, and conductors on a plastic ribbon which connects the embedded light emitting diode and plastic pressure switch to a connector. The flexible plastic membrane supports an adhesive which enables it to be stick to the surface of the module face plate. The inventive structure is more economical to build and install than presently used mechanical spring loaded push switches and light emitting diodes as they must be physically mounted to the face plate and hardwired when the module is manufactured. In addition, the inventive structure can be replaced in the field when a fault develops without disturbing or disconnecting the optical fiber connected to the front or rear of a module.

Abstract: Disclosed is a dispersion-compensating (DC) optical fiber 10 that is designed to support the fundamental mode of radiation at 1550 nm. The DC fiber is fabricated from silica glass and has a refractive index profile that includes a core region 51 surrounded by a cladding region 52 having a nominal refractive index n4. The core region includes a central core 511 having a nominal refractive index n1, a “trench” 512 surrounding the central core having a nominal refractive index n2, and a “ridge” 513 surrounding the trench having a nominal refractive index n3. A range of refractive index profiles has been found that provides relative dispersion slopes (RDS) that are greater than 0.012 nm−1 and figures of merit that are greater than 200 ps/(nm·dB). The range is conveniently expressed in terms of index differences and radial dimensions: central core: radius=1.5±0.5 &mgr;m, and 0.015<n1−n4<0.035; trench: width=4.3±1.0 &mgr;m, and −0.

Abstract: An improved fiber administration system and method of operation for a fiber distribution system. The fiber administration system contains at least one frame, wherein each frame contains a plurality of fiber distribution shelves. The different fiber distribution shelves contain numerous optical connector ports. The various optical connector ports are interconnected throughout the fiber distribution system with optical fibers. The optical fiber pass through numerous routing pathways on the frame as they travel between points on the frame. A plurality of lights are disposed on the frame proximate the different routing pathways. A controller is provided to selectively light some of the lights that correspond in position to one selected routing pathway, among the numerous possible routing pathways. The light thereby provides a visual indication of a specific routing path.

Abstract: Disclosed is a dispersion-compensating (DC) optical fiber 10 that is designed to support only the fundamental mode of radiation at 1550 nm. The DC fiber is fabricated from silica glass and has a refractive index profile that includes a core region 51 surrounded by a cladding region 52 having a nominal refractive index n4. The core region includes a central core 511 having a nominal refractive index n1, a “trench” 512 surrounding the central core having a nominal refractive index n2, and a “ridge” 513 surrounding the trench having a nominal refractive index n3. A range of refractive index profiles has been found that provides figures of merit that are greater than 300 ps/(nm·dB) and relative dispersion slopes that are greater than 0.01 nm−1. The range is conveniently expressed in terms of index differences and radial dimensions: central core: radius=1.5±0.5 &mgr;m, and 0.015<n1−n4<0.035; trench: width=3.5±1.0 &mgr;m, and −0.

Abstract: An optical fiber connection monitor has a detector adjacent the connection which detects light scattered from the connection. The detector signal is converted to a voltage and applied to a comparator circuit which gives an indication that the connection is not dangerously emitting radiation or an indication that it is dangerously emitting radiation. In another embodiment of the invention, a finite amount of light is fed from the end or ends of the ferrule or ferrules of the connection components to the detector to insure that the monitor circuitry is functioning properly in the presence of optical signals. A further embodiment includes passing light past the ferrule end to the detector, further checking the operation of the monitor system.

Abstract: A variable fiber count optical fiber cable core is disclosed. The cable core is intended for use as a part of an optical fiber cable, the optical fiber cable having an elongate cylindrical core tube formed about a longitudinal axis, and within which the cable core is received. The cable core comprises a stack of a plurality of variable fiber count optical fiber units formed about the longitudinal axis of the core tube, and housed therein. The stack of the optical fiber units will comprise at least a first optical fiber unit having a first predetermined number of fibers therein, and at least a second optical fiber unit having a second predetermined number of optical fibers therein, where the first and second predetermined numbers of optical fibers differ from one another within the stack of optical fiber units.

Abstract: A jacket for a communication cable is made from a resin that has high aspect ratio filler materials, and possibly coupling agents, dispersed therein. The fillers and the coupling agents reduce the post-extrusion shrinkage of the jacketing compound such that the strength members used in the communication cable need have only negligible compressive stiffness. The communication cable may further include a skin coating surrounding the outer jacket.

Abstract: Embodiments of the invention include an optical communications system including one or more optical transmission devices, one or more optical receiving devices, and at least one positive dispersion optical fiber coupled therebetween. The fiber includes a doped core region with an index of refraction n1, a cladding region with an index of refraction n2, and first and second annular rings or regions therebetween with indices of refraction n3 and n4, respectively. The various regions are manufactured in such a way that the refractive index value ranges are: 0.14<(n1−n2)/n2<0.31, −0.19<(n3−n2)/n2<−0.02, and −0.20<(n4−n2)/n2<−0.08. The fibers exhibit a chromatic dispersion greater than 20±2.0 ps/(nm-km) and a dispersion slope less than 0.062 ps/(nm2-km) at a wavelength of 1550 nm. Also, the fibers have a relatively large effective core area, Aeff, e.g., greater than 100.0 &mgr;m2, and a relative dispersion slope (RDS) less than 0.0032 nm−1.

Abstract: The present invention provides an optical fiber for use in fiber lasers and amplifiers wherein the optical fiber has a core member surrounded by a cladding member for receiving pump energy and transferring the pump energy to the core member. The optical fiber also has an outer layer surrounding the cladding member. The cladding member has a circular exterior periphery and a predetermined refractive index (nc). The cladding member has an index modified region that directs light to the core member. The index modified region has a stress field portion with a predetermined refractive index (ns). The difference between the refractive index of the cladding member and that of the stress field portion (nc−ns) is within such a range that the stress field portion does not affect the polarization properties of the light traveling in the core member.

Abstract: A high density optical connecting block 100 is mounted in a relatively thin, flat panel 10, and is constructed as an array of identical cells 110 that are linked together as a one-piece unit. The connecting block has a front-to-back depth that is greater than ten millimeters for imparting flexural rigidity to the panel. The array includes at least twelve cells that are arranged in two or more rows and two or more columns. Each cell has a front side that is shaped to receive and interlock with a duplex optical connector 50, and a back side that is shaped to receive and interlock with two simplex optical plugs 20. The duplex connector is a unifying structure that yokes a pair of simplex optical plugs 20-1, 20-2 into a duplex configuration.

Abstract: Mode-coupled plastic or glass optical fibers are used in communications systems to carry optical signals between transmitters and receivers. In order to overcome the high attenuation characteristics of mode-coupled optical fibers, the launch power used to transmit signals over the optical links is higher than those typically used in comparable conventional communications systems that rely on standard single-mode or multimode glass optical fibers. In order to accommodate the larger launch power levels, the communications systems are designed with receivers having a larger dynamic range than those used in conventional communications systems. In addition, the mode-coupled optical fibers can have diameters on the order of 50-62.5 microns, or even larger, thereby enabling the use of relatively simple and inexpensive butt coupling between the fibers and other system components (e.g., transmitters and receivers).