Abstract: Systems and methods are described for reducing optical fiber splice loss. A torch is described for performing a thermally-diffused expanded core (TEC) technique. The torch includes a hollow body. A conduit delivers a flammable gas to the hollow body. The flammable gas streams out of an array of orifices formed in the hollow body. The orifices are shaped and arranged in the array such that when the streaming gas is ignited, a substantially continuous elongated flame is created having a desired heating profile. Further described are a thermal treatment station incorporating a line torch and techniques for using an elongated flame to reduce optical fiber splice loss.

Abstract: Systems and techniques are described for monitoring a pre-splice heat treatment of an optical fiber. In one described technique, a lead end of a first fiber is prepared for splicing. The lead of the fiber is then loaded into a heat treatment station. While heating the lead fiber end, an optical time domain reflectometer is used to measure reflected backscatter loss from the lead fiber end. The lead fiber continues to be heated end until the measured reflected backscatter loss from the lead fiber end reaches a predetermined level. At that point, the heat treatment is discontinued.

Abstract: An optical fiber preform includes a core rod and an overclad tube having an open, distal end dimensioned to enter the mouth of a vertical fiber draw furnace. A plug is fixed in the region of the distal end of the tube, and the core rod is disposed axially inside the overclad tube so that a distal end of the rod is restrained from downward movement by the plug as the tube enters and descends into a hot zone of the draw furnace. The distal end of the tube is heated in the furnace hot zone until the tube and the plug soften and fuse with one another. The tube then collapses onto the core rod to produce a drop from which an optical fiber having desired properties may be drawn.

Abstract: The specification describes a distributed Raman amplifier with multiple pump sources for wide band amplification of wavelength division multiplexed (WDM) signals. It was recognized that using multiple pump sources introduces non-linear effects, such as four wave mixing (FWM). These effects are reduced by multiplexing the pump wavelengths in the multiple pump source. It was also recognized that not all of the pump wavelengths over the wavelength spectrum of the pumps contributes to FWM. Thus fewer than all of the pump wavelengths require multiplexing to eliminate FWM in the multiple wavelength pump source. Various approaches are described to ensure that the pump wavelengths do not interact in FWM in the transmission span. The selected individual pump wavelengths may be either time division multiplexed, or frequency modulated.

Abstract: An apparatus for tuning PM optical fiber connections has a first assembly including a light source which is connected to a first coupling stage having a rotatable polarizer, and a second assembly having a second coupling stage and a rotatable polarization analyzer for directing light transmitted through a terminated PM jumper cable coupled between the first and second coupling stages to a power meter. The output of the power meter is applied to a processing unit which, in turn, controls a rotation arrangement for the polarizing and analyzer. Crosstalk of this jumper is determined by ascertaining the angular positions of the maximum and minima outputs of the rotating analyzer, and the terminating connectors of the jumper are turned to the maximum value by aligning with a connector key.

Abstract: An apparatus and method for fabricating an optical fiber, an optical fiber preform, and an optical fiber core rod are disclosed herein. In particular, the process of fabricating an optical fiber preform involves, during a modified chemical vapor deposition process, collapsing the substrate tube into an optical fiber preform, and compressing the optical fiber preform in the longitudinal direction. An optical fiber preform that is shorter, but larger in diameter is thus formed. The optical fiber preforms therefore can be stacked during the optical fiber fabrication process, which is useful in drawing longer optical fibers with comparable outer diameter and core diameter to that used as the industry standard.

Abstract: First and second parts of a fiber optic attenuator body receive first and second end portions of corresponding optical fibers. A polymeric thermoplastic attenuating element is mounted in a third part of the body so that a first contact face of the element optically couples to an end face on the first fiber end portion, and a second contact face of the element couples to an end face on the second fiber end portion, once the first and second attenuator body parts are connected to the third body part. In one embodiment, the attenuating element is formed of a copolymer of methylmethacrylate (MMA) and trifluoroethylmethacrylate (TFEMA). In another embodiment, the attenuating element is formed from polymethyl-2-fluoroacrylate (PFMA). Both elements exhibit a reflectance of −50 dB or less, a Tg of more than 100 degrees C., and a transmission of more than 85% at wavelengths from 850 nm to 1620 nm.

Abstract: Techniques are described for reducing splice loss between a pair of optical fibers. A first fiber is spliced to a second fiber at a splice point. A region of the spliced fibers, including the splice point, is thermally treated to cause a controlled diffusion of dopants in the region. A controlled tension is then applied to the splice region while heating it to a predetermined temperature to produce a controlled change in the splice region's strain state. Further described is a heat and tension station for performing a heat and tension technique on a pair of spliced fibers.

Abstract: Optical fibers are described that exhibit reduced splice loss. Further described are techniques for fabricating optical fibers exhibiting reduced splice loss. One described fiber includes a plurality of regions, one region having a higher viscosity and the other region having a lower viscosity, such that when the fiber is drawn under tension, a strain is frozen into the higher viscosity region. A lower viscosity buffer layer is sandwiched between the higher viscosity region and the lower viscosity region. The buffer layer isolates the lower viscosity region from changes in refractive index in the higher viscosity region arising from a change in the strain frozen into the higher viscosity region.

Abstract: The present invention provides a method of preparing preforms for optical fibers. The invention allows one to remove or significantly reduce undesirable refractive index variations in the central portion of the optical fibers. The method of preparing the preform having a central duct includes the steps of a first collapsing step, an etching step and a second collapsing step. The first collapsing step reduces the size of the central duct without closing the central duct by heating the preform at a first preform collapsing temperature. A portion of the last deposited layer of the core glass layers is etched by flowing an etchant gas through the central duct at a lower temperature than the preform collapsing temperature. The preform is finally collapsed at a second collapsing temperature to close the central duct of the preform and form a solid rod.

Abstract: Defects in optical fibers are detected during manufacturing by using three bandpass filters to separate signals from a scattered light signal produced by a light source in a fiber measurement system. The separated signals include a clad diameter signal, a regular airline signal and a core airline signal. The regular airline signal is compared with the clad diameter signal to produce a normalized regular airline signal, and the core airline signal is compared with the clad diameter signal to produce a normalized core airline signal. The normalized regular airline signal and normalized core airline signal are monitored to determine if they increase, which indicates the presence of a defect in the optical fiber.

Abstract: Methods and apparatuses negate a measured mechanical twist of an optical fiber by introducing a counteracting twist to bring the net mechanical twist closer to zero, which reduces the fiber's polarization mode dispersion (PMD). A spool of optical fiber having undesirable mechanical twist is mounted and fiber is drawn from the end of the spool to impart a specified counteracting mechanical twist. Additionally, the spool may be controllably rotated by a control system while optical fiber is drawn there from, allowing the system to generate a precise amount of counteracting mechanical twist in the fiber.

Abstract: An optical fiber suitable for generation of a supercontinuum spectrum when light pulses of femtosecond (10−15 sec.) duration are launched at a certain wavelength into the fiber. The fiber includes a number of sections of highly non-linear fiber (HNLF) wherein each section exhibits a different dispersion at the wavelength of the launched light pulses. The fiber sections are joined, for example, by fusion splicing the sections in series with one another so that the dispersions of the sections decrease from an input end to an output end of the fiber. In the disclosed embodiment, a low noise, coherent supercontinuum spanning more than one octave is generated at the output end of the fiber when pulses of light of 188 fs duration are launched into the fiber at a repetition rate of 33 MHz and with an energy of three nanojoules per pulse.

Abstract: An optical fiber suited for dispersion compensation with simultaneous Raman amplification. The fiber has a central core and an index profile that defines successively concentric regions radially outward of the core. The core has a diameter of between 2 and 5 microns (&mgr;m) and a refractive index difference (&Dgr;n) with respect to the outer cladding of between 0.012 and 0.035. A trench region adjacent the core is between 2 and 6 &mgr;m wide and has a negative &Dgr;n of between −0.015 and −0.003. A ring region adjacent the trench region is between 1 and 5 &mgr;m wide and has a &Dgr;n of between 0.001 and 0.015, and an inner cladding surrounding the ring region has a width of between zero and 5 &mgr;m and a &Dgr;n of between −0.011 and 0.001. A dispersion slope compensating module (DSCM) including the fiber obtains a relatively high Raman gain with respect to conventional DSCMs that are pumped for Raman amplification.

Abstract: A fiber optic cable is disclosed that buffers against loss, where the cable includes an outer jacket, and an optical fiber ribbon disposed within the outer jacket, wherein the ribbon includes more than one optical fiber, and at least two distinct matrix coatings disposed on the optical fibers, the coatings having distinct characteristics. Preferably, the inner coating is relatively soft, with a lower elastic modulus than the relatively stiff, hard outer coating. Also disclosed is a method of buffering loss in an optical fiber transmission, including providing an optical fiber ribbon, wherein the ribbon includes more than one optical fiber, and at least two distinct matrix coatings disposed on the optical fibers, the coatings having distinct characteristics; and transmitting in at least one of the C-band, L-band and U-band of wavelengths.

Abstract: Connector systems for dynamically updating information related to a network and methods for developing the connector systems, are provided. A connector system for dynamically updating information related to the network, comprises: a connector; and an integrated circuit integrated in a surface of the connector. A method for developing the connector system comprises: obtaining a connector; and integrating an integrated circuit in a surface of the connector.

Abstract: A variable attenuation device for optical signal transmission has first and second ferrules or plugs having abutting end faces, one of the ferrules being rotatable with respect to the other while axial alignment therebetween is maintained. Each ferrule or plug has an axial bore aligned with the other and contains the end of an optical fiber, with a fiber having a smaller diameter than the diameter of the bore in which it is contained so that the fibers may have decreased engagement with each other when there is relative rotation of the ferrules although the ferrule bores remain aligned.

Abstract: A connector plug for an optical fiber polarization maintaining connector has a front housing portion from which extends a cantilevered latching arm having a cross-sectional shape of a truncated wedge, and a rear housing portion. A barrel assembly having a flange thereon and a ferrule extending therefrom is housed within said first and second portions and is incrementally rotatable with respect to the first portion of the housing and hence to the latching arm. In a first embodiment the flange is seated in the front portion and prevented from turning with respect thereto. In a second embodiment the rear housing portion is an extender cap having resilient clamping arms which grip the flange. The extender cap is incrementally rotatable with respect to the first portion of the housing and, hence, the ferrule is incrementally rotatable with respect to the latching arm.

Abstract: Systems and methods are disclosed for measuring Polarization Mode Dispersion (PMD) of single-mode optical fiber. The method allows for a faster and easier method of accurately measuring intrinsic ultra low PMD optical fiber in a low mode coupling state. The method involves the introduction of a plurality of localized external perturbations on the optical fiber, after which the optical fiber is allowed to reach a steady state, and then measurement of the differential group delay occurs using standard measurement techniques. The plurality of localized external perturbations is altered followed by another measurement of the differential group delay. After obtaining a sufficient number of measurements to provide a Maxwellian distribution, the Polarization Mode Dispersion value can be calculated as the average of the distribution.

Abstract: Embodiments of the invention include a method and apparatus for making optical fiber preforms and optical fiber. The method includes the steps of positioning an overclad tube around a preform core rod, heating the overclad tube along the length thereof in the presence of a pressure gradient to collapse onto the preform core to form the overclad optical fiber preform, and adjusting the radial size of a heated portion of the preform core rod and/or the overclad tube to actively match the radial dimensions of the preform core rod along the length thereof with corresponding portions of the overclad tube. The active matching reduces variations in the physical dimensions of the preform core rod and/or the overclad tube, which improves transmission and other performance characteristics of fiber drawn from the created preform, e.g., by maintaining a relatively constant D/d ratio of the preform.